Ep. #832: Dr. Bill Campbell on Re-Evaluating the Science of Rapid Fat Loss

Mike: Hey, and welcome to another episode of Muscle for Life. I’m your host, Mike Matthews. Thank you for joining me today. And if you haven’t already, please take a moment to subscribe to the show in whatever app you are listening to me in so you don’t miss any of the new episodes. And it helps me by boosting the rankings of the show in the various charts.

Okay? So in this episode, I chat with scientist and buddy, Dr. Bill Campbell, about a new study on rapid fat loss that came out of his lab. And this was an interesting discussion because in this study what Dr. Campbell looked at is how aggressively can we. Cutter calories. So long as we know what we’re doing with our macros, with our protein intake and we know what we’re doing with our exercise regimen, how aggressive can we be with our cutting to maximize fat loss while still minimizing muscle loss?

And many people say that we can’t be all that aggressive. Many people say that if we cut our calories more than maybe 20% or so, if we eat less than about maybe 80% of the calories we burn every day, we are going to start losing muscle. We are going to start having terrible workouts. We are going to start feeling miserable.

And this is something that I’ve questioned for some time. I’ve told people to not exceed 25% because in my experience working with a lot of people over the years, it did seem that once you got to 30% plus in terms of the size of your. Calorie deficit. Things started to sour, at least workouts, energy, mood, not necessarily muscle loss.

Of course, rapid fat loss was fun, but at what cost? And there’s not just the physical component, but also the mental component and the emotional component. That said though, something that has been established in the scientific literature and something that I’ve noticed anecdotally with many people, if you have a lot of fat to lose, you can be very aggressive with your cutting and experience.

No major negative side effects. You can. Eat 30%, maybe even upward of 40% fewer calories than you’re burning every day for a period and lose a lot of fat and maybe even gain muscle if you’re new to resistance training and feel totally fine. And so I have wondered over the years, how does that apply to those of us who are pretty fit?

And those of us who want to go from, let’s say, lean ish to very lean, especially those of us who have gained a lot of muscle. And again, that is what Dr. Campbell’s study looked at specifically. And if you are not familiar with Bill, he is a professor of Exercise science and the director of the Performance and Physique Enhancement Laboratory at the University of.

Florida and he has also published more than 150 scientific papers. So he is somebody who is not just interested in this stuff academically, but he is in the trenches. He is at the coal face doing the hard work, and he’s a super nice guy and he’s fun to talk to. Also, if you like what I’m doing here on the podcast and elsewhere, and if you wanna help me do more of it, please do check out my Sports Nutrition company Legion, because while you don’t need supplements to build muscle, lose fat and get healthy, the right ones can help.

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Ske alon over to there. Save big hurry up though because no matter what my exorbitant e r P software per predicts, we always run out of stock of at least a thing or two every year. During our big Sitewide sales, especially our Black Friday sale, there’s always that flavor, or two or three or that product, or two or three that just blows up out of nowhere.

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Bill: Yes I’m, I think this is my second, maybe third, 

Mike: Yeah.

Yeah. I thought it was the second, but you might be right. It might be the 

Bill: third. I think it’s the second. So thank you for inviting me. 

Mike: Yeah, absolutely. I’m excited to talk about rapid fat loss with you. And you had mentioned just before we started recording that this is a study you did that you can talk about because you presented at a conference.

It’s not officially out yet, but that the results made you change your mind about something, which is it’s funny because I think. It’s just an interesting question that I’ve been asked and I’ve answered myself, I believe on the podcast. What is an example of something that I have changed my mind about in the context of fitness in the last, year, two years, three years or whatever.

And if I remember correctly I gave four or five or six different things. And, but that’s something that is, I think it’s a useful question to ask ourselves just in general. I think in any area of life, and I don’t wanna go off on a long tangent unrelated to rapid fat loss, but I think that if.

And this will certainly be the case for me if I were to look back and say, look at myself a year ago, three years ago, five years ago. And if I couldn’t quickly pinpoint key changes in perspective, it doesn’t have to be necessarily a complete 180 change but something that, some ideas that, that were somewhat foundational in how I live my life or how I view the world.

And if that has not changed at all, if I couldn’t answer that question, if somebody were to say, Hey, what are a few things you’ve changed your mind about that are important in the last couple of years? I would be concerned. I would say I’m probably not doing a good job learning and thinking and trying to get better, 

Bill: yeah. That would be an unexamined life. I 

Mike: think yeah, I completely agree. And so in the case of my work, it’s the same thing as where I’m happy cuz I look at it as more like we are finding out how to be more right. I don’t look at it as, oh, I was wrong even though I was wrong about things in fitness a couple of years ago.

And there are certainly things that I am wrong about right now. Maybe I don’t know what they are yet, but I’m happy to find out what they are because then I can be more. Do you look at it the same way? Yeah. Yeah. 

Bill: And it’s funny, I, cuz I’m a scientist, like I, I get paid to read research paid to do studies, and I have a lot of assumptions only because I haven’t had time to dive into the research in all of these areas.

And then when I do get the time, or it’s time for me to look into an area, I’m like, wow, the research doesn’t support that at all. And all these years I thought that this was true. So it’s, Yeah, it’s I think that’s 

Mike: life though. We have to, we don’t have the time to confirm every single thing that we assume to be true.

There are things that we have to say I guess I could call that a believed fact, right? I haven’t confirmed it, but I’m just gonna operate under the assumption that it’s true until proven otherwise. 

Bill: Yes. Yeah. And if it’s not, if it’s one of those things that really doesn’t matter, No big deal.

But of course, yeah. It’s We don’t, I don’t wanna go down this rabbit trail . 

Mike: Yeah. But we’re not here to pacifies. But, 

Bill: maybe no, but I’m actually bringing it back to fitness. The thing that I’ve been pouring myself into is concurrent training. And part of my research, I also do Google searches on this stuff as well.

And one of your articles, I don’t know if you wrote it, but it was a Legion athletics. It was like right at the top. And I had already done 90% of my research. And I’m gonna, I’m gonna read this, and of course I like Legion. I know you. I’m like, I wonder if they got this right or 

Mike: maybe not.

You gotta let me know. Cause I think that article, if I remember correctly, that article was written by, his name is Army. Interesting, unusual name. That’s it. Army Lege or something? Yeah, exactly. Yep. So he’s the director of content for Legion. And so as you can see, he writes at the website and this is an area of particular interest to him because he used to do a lot of endurance.

Like he has competed in triathlons and marathons and and he’s been really into weightlifting now. He’s more into weightlifting and he does endurance stuff, not competitively, just because he enjoys it and he wants to reap the health benefits. But this is an area that he has a lot of firsthand experience in.

And he’s been very interested in the research. So you have to let me know your take on his take. And I’ll stand behind his take and it’s in line with my understanding of things. But hey, we may be wrong. No, like 

Bill: I said I had done about 80% of the work and I’m still doing work.

I’m getting down to the last few studies looking at muscle biopsies and muscle specific measures, like MRIs and CT scans on muscle hypertrophy. But yeah I already came to my conclusion and just, you would appreciate this. I can’t stand reading review papers or meta-analysis first.

I don’t, I wanna read original articles first, get through, at least six of those papers. Cuz then I feel like I know where their literature’s taking me. And then at the end, now let me read the review papers, which is where I’m at now as well. And so I had already come to my conclusion that this whole concurrent training thing, at least as it relates to muscle hypertrophy strength, I think there are, there’s an interference effect.

Potentially not across the board. But on hyper, there’s there’s very little there. And I was like, I always thought that there was, and it I don’t like doing cardio, so I was happy to live there. So again, that’s a whole, we can do a whole podcast on that, but yeah, the article that Army wrote was, it was so well done.

It was Oh, so 

Mike: you did? I came. Okay, good. All right. Cool. Yeah and that’s, Hey, that’s nice to hear because again he’s a smart dude and he’s into this stuff and and then my take on it was right in line with his, and so sometimes, when we’re planning out content, some things he’ll say, Hey, I’ll take this, other things I’ll take.

And that’s when he wanted to take, because again, it’s something that he really, you know, likes and he’s put more time actually into researching it than I have. And he has I, to, to your point, I think he and it sounds like you came to a similar conclusion that. It also is probably not very relevant to, let’s say everyday gi Jim goers or even like lifestyle body builders as opposed to a competitive strength athlete who’s at an elite level.

And particularly for that point of hypertrophy and even the strength performance, so long as you’re willing to make maybe a few concessions on the cardio front. If you’re a very cardio focused and you really want to maximize your endurance performance okay, that, that may cause some issues.

But if you’re willing to think of it more as cardio, as opposed to, again, something that you’re gonna track and push and really try to like, squeeze every ounce of performance outta your body, then there’s probably not much to worry. No, and the way 

Bill: that I’ve come to explain this, cuz again, I’m, I was just this morning trying to tell, talk to my wife.

I’m like, Hey, I gotta be careful cuz I don’t want people thinking that you can do, run marathons and you’re not gonna lose muscle. That’s not what I’m saying. So my, the way that I’m understanding it is if you want to do aerobic exercise as a supplement to your basic resistance training program, like you are saying, I don’t, I think your level of concern can be relieved.

Now, clearly what we don’t have is data in if b professional male body builders who have, 80 pounds of mass over the years, and I don’t know, if there’s gonna be an interference effect there, it may be I would may, be a little cautious, but. In all of the populations that are published, which is again, not elite level body builders.

There’s I’m having a hard time finding evident any evidence to support an interference effect on muscle hypertrophy. And, there’s some studies that actually suggest that it helps with hypertrophy. Yeah. 

Mike: I know in the case of cycling in the legs, for instance. Yeah. 

Bill: Yeah. And again, that, that literature, males, females, elderly, young, obese, lean cycling, running, elliptic it, that’s where it gets hard to come to firm conclusions cuz the variables are all over the place.

Length of the studies, the intensity of the cardio, the duration of the cardio. But yeah. I was reading that article and yeah, I was like, Wow, this is it confirmed my own research in looking at that literature. I’ll pass that 

Mike: along to Army. He’ll like to 

Bill: hear that. Yeah. Yeah.

Please give him my sincere compliments on his writing ability as well. It was pleasure to read. 

Mike: That’s great. Yeah, I’ll definitely tell him he’ll appreciate that. Cuz he, that’s his primary. Work. And that’s what he really, what he likes to do. He likes to read and research and he likes to write.

So that’ll be a nice compliment. But let’s shift gears now and talk about rapid fat loss. And again, I had mentioned before we, we started talking about concurrent training, that this study that you conducted it, it made you change your mind about something related to rapid fat loss.

Maybe we should start there just because it’s interesting. I wanna know. 

Bill: Yeah. So I, again, just trying to guard against my message being taken to places where I don’t want it to be taken. I’m not advocating for crash dieting, so let me start there. But if you want to signif severely reduce your calories under certain conditions I now think this can be done without much harm to your muscle mass.

I don’t think I would’ve said that a year ago or six months ago. And again, what we can talk about, what are these things that you need to do, which they’re not shocking in our space, But yeah, I’m 

Mike: not, let’s get into the details. So what does this look like? People listening are now wondering, Okay, when how much of a calorie deficit are you talking about?

And for how long? And how do I, how would I do that correctly and when should I consider doing that and so forth. 

Bill: So let’s, without going into the minutia of, there’s multiple other studies that have reported severe dieting or large caloric deficits. Cause pretty a or a cellular reduction in animalism.

So an increase in muscle protein breakdown, a decrease in muscle protein synthesis. So I don’t wanna make that argument’s already there. So there are other studies that have shown harm with severe caloric restrictions, particularly those where there’s no resistance training and we’re higher protein intakes aren’t followed.

. So that’s a given, or at least let’s assume that’s a given. Yeah. What we did in our study was we did a, we wanted to challenge, cuz I, I said I want to I don’t think severe caloric restriction or even aggressive caloric restrictions or a good idea. So I’m at a, 

Mike: What’s aggressive to you?

I’m curious. 

Bill: I would’ve said I think the literature leads me to believe over 30% is where I see some pretty aggressive studies. Yeah. Showing that might not be ideal for maintenance of muscle mass. So I’m at a point in my career now where I have my thoughts and I’m starting to design studies to challenge my own thoughts.

So here was the first study can we be aggressive? And what we did was we said, Can we be aggressive with a caloric deficit? And I’ll define what that was, but let’s put in everything we know that will help prevent the loss of muscle and help prevent the suppression of metabolic rate. Yeah. Or metabolism.

So we, we basically said we’re gonna do three things. The caloric deficit, we’re gonna, I want it to be severe, severe at a point where people can actually stick with it. So we said about 37.5% over a two week period. So nearly 

Mike: About double what would be considered. Like a, not, maybe not aggressive, something around 20%.

That’s usually where I would cut it off. 20, maybe 25 if I’m feeling frisky, 

Bill: Yeah. I think my base is 25%, just so people can feel the and again, our research would suggest that’s a very good place where you can maintain muscle mass. Yep. So there we said, okay, 37 and a half percent, let’s just call it approximate or approaching 40% of a chloric deficit.

So it was only two weeks where they had to live here. We spent two weeks prior to that determining their maintenance calories so that we could, be very specific about hitting this near 40% caloric deficit. So there’s the first Safeguard we put in, it’s only gonna be two weeks.

We’re not asking you to do this for three months or four months, that would just be obscene. Where they’re, people are eventually gonna lose the battle to hunger. The other thing we did, which we do in all of our studies is we also said, you’re gonna have, you’re gonna resistance strain.

That, that provides an anabolic stimulus to the body. So that will help preserve muscle mass. I don’t know if it will help in this case, cuz that’s a pretty severe caloric deficit. And then the other thing was a relatively high protein intake. So we instructed all of our subjects to ingest one gram per pound during this near 40% caloric deficit or 2.2 grams per kg of body meds.

So short and throwing in proteins and anabolic nutrient resistance trainings and anabolic exercise modes, trying to throw in as many an. Variables into an otherwise very catabolic environment, which is a low caloric a low caloric intake. So that was the study design, and this was males and 

Mike: females. A simple approach though, that anybody can do.

Bill: Yes. And that’s one thing. My studies aren’t perfect, but they’re practical. That they are designed for people to, to be able to do with, generally speaking, with tools that people have. If you can track your macros, if you can have somebody test your body fat with skin folds, my research speaks to you.

It doesn’t get, I’m not doing biopsies. Not that there’s not value in that, but. I place a high premium on relevance to normal people with what we do. So at first glance as I’m gonna share the results with you, the data’s not good, but we took one extra step. That is what flipped the switch for me.

So they these subjects guided for two weeks. Oh. It’s also, it’s important to know that this happened in the middle of Covid, so we had to shut down the study halfway through. And when we had the shut, we had just gotten finished with half of the subjects in the study. And all of those subjects, half of them they worked out in my lab, so I’d like to supervise all of the workouts cuz that gives you a lot more confidence in what they’re doing.

And something else we did that was unique, we had them tell us what their normal programs were and then what was their set volume. And then we just allowed them to continue doing what they were normally doing. So we didn’t have a set program. Instead we said, Do what you normally do. Of course it’s in my lab.

So there might have been a few adjustments, but the volume didn’t change and. That allowed us to say the real, the only real intervention here is a caloric deficit. Yeah. It’s smart. So then, yeah, and you watch the future of resistance training studies is gonna do exactly that cuz it, it does not make sense to give everybody the same program because as half the subjects are doing half as much weight, some doing three times as much.

And it’s, it totally convolutes your data. So I think you’re gonna see, 

Mike: and that volume point is big too. You bring somebody in and then you ask them to do now 30, 40, 50% more volume than they are used to doing that is going to induce changes like that is going to have its own effects. 

Bill: Yep.

Yeah. So you hear me predict the future of , the research landscape as it pertains to resistance training. And then after, not after Covid, but because we’re in Florida and we took a lot of, I mean I spent a lot of money and by the way, Legion has donated money to my lab to just no strings attached.

They just said here, if this helps your research. So Mike, I need to thank you. I need to thank Kareem. That money that you guys donated, at least some of it literally was me buying, all the gloves, all of the Covid wipes that kill Covid on surfaces. Face masks so I, I need to thank you for supporting my research because if I ever needed money, th this was the time because those supplies at that time were not cheap.

So thank you. 

Mike: Yeah, my pleasure. Unfortunately I had to go to that stuff, but hey, the money was needed. , I’m glad. Yeah, I’m glad you were able to make it happen. 

Bill: So the second half of the study, because of this covid environment we weren’t able to supervise all of the workouts any longer.

So we supervised some of them, but not all of them actually. And we, that might have been a study, we weren’t able to do any of that. So do, we couldn’t supervise them all only because of the covid caveat. But of course we were able to, use all of these safety supplies to keep testing the subjects for their body composition, metabolic, and 

Mike: unfortunately they were just doing their normal programs.

So yes. Not that supervision wouldn’t have been valuable, but like you said, that is a safeguard that you just wanted them to keep training the way they normally do. Yes. 

Bill: So after the two week, and I’m just gonna focus on the fat loss portion here. We actually had a two week post diet period, and we can talk about that later if you want.

But I the real value in this is what happened with the fat loss. And there was no inter, there was no comparison here, there, there was a, I’ll say there was a comparison, but for the sake of what we’re talking about, this was just to see if you have this severe caloric deficit, do you maintain muscle mass on how much fat do you, So that’s the main question.

So very simple study design. After two weeks of, and this is 14 straight days, there’s no diet breaks, there’s no refeeds here. 14 straight days of this nearly 40% caloric deficit. They lost about it was, what was it? One and a half kgs, let’s say a little over three pounds of body weight.

And then we look at what’s the composition of this weight loss. So the, to me, the standard is, and this really comes from the obese literature, the standard is about three fourths of your weight loss should come from fat. And about one fourth should come from, or not should, but typically one fourth comes from fat free mass.

And fat free mass isn’t total muscle. There’s, it’s body water, it’s connective tissue, it’s organs, but clearly there’s a direct relationship. If you lose fat free mass, you can I think you can be pretty confident that you’ve lost muscle mass. If you’ve gained fat free mass, you can be confident that you’ve gained muscle mass or contractile tissue.

So this was the next thing, like what was the composition? Are we better than what we typically see in the literature? The answer is no. The fat loss accounted for two thirds or 66% of the weight loss. And then the fat free mass was one third. So about 33%, which again, I use it just as a standard guide if, and my other research studies, because we have high protein, because they’re resistance training.

When dieting we’re very close to having a body of Recomposition standard in our weight loss study. So this was the first study where this happened. And again, it’s probably not surprising. They had a pretty severe caloric deficit, even though it was only two weeks. But then we looked at next, the next analysis that we looked at was total body water.

So we track their body water. 

Mike: And that was gonna be my next, that was gonna be my question, so I’m listening. Yeah, 

Bill: so you can probably see where this is going. So they lost, I set up one and a half kgs of total body weight and a third of that was fat free mass. So half a kilogram or about a pound.

But when we looked at the loss of body water, 80% of the fat free mass component was water. So they lost water. And what that means is the amount of what we call dry fat free mass, which is now, I mean you’re talking minerals, protein, so much more of this is now your muscle. It was very small and no significant difference.

None. When you accounted for the water loss over the two week period in this fat free mass component, they did not lose any muscle mass. Again, it was 0.1 kilogram. Of fat free mass. And again, that just still not all that’s still not all contractile muscle tissue. Exactly. That’s 

Mike: still whatever was or might have been.

Let’s remember, you know this, but for people listening, let’s also remember that when these people, let’s say this was gonna be the beginning of a cut. For them. Let’s say they wanted to start this way and they were gonna continue in a deficit and whatever small amount of contractile tissue they might have lost in this initial phase and that they might lose over the next few weeks, whatever will come back very quickly once they come out of a calorie deficit.

So I always like to point that out for people who get, I think, a little bit too concerned about losing small amounts of muscle while cutting. Especially, I’ll hear from people sometimes where they’ll do great they’ll cut for, it might be two or three months, maybe a couple diet breaks in there, but they’ll do a great job.

Theyll lose a lot of fat and, but they’ll be very stuck on the fact that, oh, they got DEXA scan and it said that they lost also five pounds of muscle. And I’ll point out this body water point that like you didn’t lose five pounds of muscle tissue. And then also whatever muscle tissue you might have, Lost.

Remember, you’re gonna gain that back in your first couple of weeks of just eating normal again. So just take a w like you did. 

Bill: Yeah. And two thoughts on that. One you have to embrace the phase that you’re in and if you’re in a fat loss phase, and I appreciate, do things to protect your muscle mass, but don’t shortchange yourself, embrace a fat loss phase if that’s what you’re trying to do.

Don’t, don’t tiptoe around it cuz why do it at all then. Yep. And then the second thing is, yeah, we did a two week. Add li So whatever they wanted to do, and they gained back actually a marginal amount of dry fat free mass than what they had more of that than that. They started the whole, than what they started the diet with.

So it, not only did it come back, actually, it actually, they actually had a little bit more, not nothing statistically significant, right? Something else. We also measured resting metabolic rate, and that’s a great proxy for muscle mass because the large, other than body weight, the largest predictor variable of resting metabolic rate, at least in males, is lean body mass.

And we did have a significant loss in the first two weeks of, and again, that’s not all muscle mass and weight loss. That also closely tracks just caloric intake. So that’s another huge component. If you want to increase your metabolism tomorrow, eat a lot today. 

Mike: Yeah. And it will go up. So I, The thermic effect alone.

There you go. You’re gonna burn some more energy. 

Bill: Yes. But in the two weeks after me, not only did the dry fat free mass come back and the fat free mass, but also resting metabolic rate came back as well. Yeah that’s a good point or a good perspective to have. You’re not losing all muscle and you do get it back.

Now you could make the argument that is a month or however long your diet is. That is time that you didn’t build new muscle. And I can appreciate that. But again, 

Mike: you’re, but you, I’m assuming you wanted to cut for a reason, , it’s 

Bill: Yes. And again, I’m, My message is always protect muscle.

Protect muscle, but embrace the phase you’re in. You’re gonna have, hopefully large parts of the year where you’re gonna build muscle. Yeah. And I don’t think that, I think what you’re saying probably is true. You’re never losing that muscle and it’s gone forever. It’s a short term. Fixed.

So it, as it turned out, we’re talk. We, I did say high protein. So about on average half of their calories were coming from protein in this study in some subjects who were eating low calories to start, because we set an absolute amount, they were eating almost pure protein , 

Mike: which is, So I was gonna ask you, I have a few follow up questions.

If Yeah. So one is, I’m sure that you are familiar with the protein sparing modified. Fasting approach to dieting and that, that’s something that I first heard about years ago from Lyle McDonald. He had spoken about it and if I remember correctly he didn’t just give it a blanket endorsement.

He felt that it was useful. I don’t wanna put words in his mouth, but if I remember correctly, it was useful for certain people under certain circumstances, basically. And so this I wanted to get your thoughts on how what you saw here compares to what has been seen. I know there’s limited research on that.

And then and then from there, I’d like to hear your thoughts for people listening, wondering. How, what would be a practical use for this? And I know that they’re gonna be thinking about, Okay, we have a two week duration. What if can I like, can I do this for four weeks and quickly strip off a bunch of fat?

And so I don’t wanna throw too many things at you. I’ll I’ll hold the rest of the questions in, but 

Bill: yeah, so I, I think our study is the closest thing you’re gonna find in the population that 

Mike: that we kinda serve. Yeah. Which is great. Which is cool. Yes. 

Bill: Yeah. I wouldn’t say it’s a protein.

A very high, it is very high relative to literature, but believe a protein, What’s that? What’s the term? A 

Mike: Yeah, pure MF protein sparing modify f Yeah. That, if I remember, that’s like pretty extreme. You basically eating 1 50, 200 grams of protein per day and that is it. 

Bill: Yeah. So we did, I’m not gonna say we did that.

Yeah. But again, this is the closest thing to that. And in some subjects, 10%, 15% it literally was that. And I think that makes sense to me. If you’re trying to lose fat quickly, give your body as much anabolic variables or an and anabolic stimulus. Protein is anabolic resistance. Exercise is anabolic and caloric deficits are not.

So offset that. So we, again, we, you could say we just threw everything we knew. At this to, to protect muscle. And we did everything we could to protect metabolism. And it could have been worse. I guess it could have been better. is what it is now, again after four weeks, it was back to a non-significant decrease from baseline.

And then what was your second question? Oh, yeah. How can this be applied? Yeah. Can we do this for four weeks? I think that’s the million dollar question. Yeah. How can we go a third week and not see a decrease in dry fat free mass? How long can we go now, at this point I’m gonna say, if you’re gonna do this, it needs to be short.

Cuz that’s what my data suggests. But maybe longer. Maybe you do a feed after the first two weeks for, 2, 3, 4 days and then do another two weeks. The research is and that’s where we’re gonna go next. We’re going to build off of this and start asking those next questions.

So if you have ideas on what you think’s most relevant, let me know because that might be what we do. 

Mike: If you like what I’m doing here on the podcast and elsewhere, and if you wanna help me do more of it, please do check out my Sports Nutrition company Legion, because while you don’t need supplements to build muscle, lose fat and get healthy, the right ones can help.

Legion is also holding its biggest sale of the year right now, and its biggest sale ever. You can save up to 40% on everything, plus get free gifts on all orders over $99. And you can do that right now [email protected]. B y l e g i n.com. Yeah, that, that would be an interesting approach. And by Refeed, I’m assuming you’re thinking bring calories back up to maintenance.

Yes. maybe five days or some, something, maybe a little bit longer. 

Bill: Yeah, that I would define that as a diet break. Refeeds? Yeah. Would Oh, 

Mike: You’re thinking shorter. Okay, good. 

Bill: Yeah. Because again, I wanna embrace the fat loss phase, but anything’s in play here.

Something else I’ve thought about is what if we did a re, what if we did this for a month? But every weekend. So it’s very aggressive, but every weekend we go back to maintenance, and then we have another group who just just goes, no refeeds and they’re not quite as aggressive.

So there’s an, the i the rabbit trails are endless, but I think this is very practical and part of my philosophy is I don’t want people to be. In a perpetual diet. So part of the thinking of this study was, can we come up with something where if your motivation is high, can we leverage that where you’re highly motivated to, to beat hunger for a short period of time.

So almost let’s kill it for a short period of time and then get out. And by getting out not, not having a food orgy for the next month, going back to maintenance, and then maybe in another month, kill it again. So that’s kind of part of the motivation here is almost like intermittent aggressive approaches rather than the typical longer duration diets that people inclined 

Mike: to do.

That could be interesting in the context of even lean gaining, if you think about the slow fat accumulation that comes with a slight calorie surplus and then hitting it every so often with some aggressive Cutting. To ultimately with the goal of course being, if we were to look at it over the course of a year, just being able to spend more time in a calorie surplus as opposed to the more traditional where you’re lean bulking until you’re just too fat basically.

And then you have to cut for probably in most people it’s at least a couple of months. It’s at least eight weeks, may, maybe as long as 12 weeks before you, you are lean enough to do your next round of lean bulking. So there’s the element of that I guess would be more related to efficacy.

And then there’s also enjoyment. I know a lot of people, of course, they don’t particularly like that approach. They, because they. The beginning of both of the phases usually, and I’ve experienced this myself, the beginning of that lean gaining phase is cool because you’re eating more food and you’re having great workouts and you, you’re usually, you’re just noticing more energy and maybe even better sleep.

But then as you get deeper into a lean gaining phase, you get sick of eating so much food and you have. Continue to increase your calorie intake, usually to continue gaining, and then you really get sick of eating food . And then you start cutting and it’s nice to just cut your calories literally in half.

Maybe that’s how it was. I haven’t done that in a while, but my last lean gaining phase, it ended at about 4,000 calories per day. I felt like I was forced feeding myself my final, final meals of the day. I just felt gross basically every day. And and I started my cut, maybe not at 2000, maybe 2,500, but it was a relief just to, to not eat 4,000 calories per day.

But then of course, after the first month or so of that, eh, now the workouts are starting to flag and energy levels are lower and you just keep going obviously. But it may be more enjoyable to do what you were just suggesting, and this would be on an individual level, but again to use that calorie surplus.

And for the timing, maybe it’s a month or something. It depends on, on, obviously very obviously it depends on various factors, but then to do an aggressive fat loss for a couple of weeks where you almost still have that momentum built up from the calorie surplus and may, maybe in those couple of weeks you don’t get any performance bump, but you don’t notice any reduction either.

You just get a bit leaner, you lose a couple pounds of fat and get right back to it, 

Bill: yes. And something else. Earlier this summer I was really diving into these, this constrained energy expenditure model. I imagine you’re familiar with that. Yeah. Yeah. And it’s funny I’ve heard you say, So I did all that research and then I wanted to end it with reading the book Burn.

And I’ve heard you say on your podcast you’ve read more than a few books where the books were way too long. Like they would just get to the point, That’s how I felt like that 

Mike: burn book was, I hate that age. It’s such a pet peeve of 

Bill: mine. . Yeah. It was like this evolutionary biology. I’m like, I just wanna know, do I not lose weight after a while?

Like Yeah, the two chapters in the middle covered that grape. Yeah. 

Mike: You’re like that could have just been an article. Come on. Yes. 

Bill: But if, and I do believe there is. Validity to this constrained energy 

Mike: model you want. Do you wanna describe what that is for people 

Bill: wondering? Yeah. Oh yeah. Good point.

In two, two, and we live this isn’t a shock that people, when I explain it like this, if you go on a diet for an extended period of time, do you keep losing weight? The answer is no. Eventually things slow down, and so that’s if you’re dieting. The other side of this is what if you start increasing your aerobic activity and you start to lose fat initially, If you keep that aerobic activity the same level, the same duration, frequency, or let’s just say the same volume for the next six months there, you’re gonna keep losing body fat at the same rate.

The answer’s no. That’s not surprising to anybody. So I think everybody intuitively believes yes, the body kind of works against you over time. That’s essentially, to me, that’s how I’m, that’s how I define the constrained energy expenditure model and. I think the popular the mass media version of this is taken way too far, where if you do any aerobic exercise, it’s worthless.

Yep. It’s you’re gonna slow down your metabolism to the point that you might as well not even do it. And that’s not, that’s just simply, 

Mike: I’ve seen the a more recent take on that, cuz that was the mainstream myth for a while. And I’ve seen a new one, which is, okay, fine, maybe there’s not much in the way of metabolic decline or adaptation, but compensatory eating that, like you keep, you just not gonna be able to stop yourself from increasing your calorie intake, negating any of the caloric benefits of the exercise.

That’s a new one. And 

Bill: I, because of the natural the natural consequence of this, I went in, I dove into that literature as well. I spent a lot of time this summer on this stuff. And to that, I, the research has led me to think that’s not true. 

Mike: Certainly in some people, right? I mean on yes, highly 

Bill: individualized.

And I’ll give you a number, like an actual number from a mathematical model where some researchers publish it. I can send it to you, you might already have it. But what happens when you do a aerobic exercise, do you eat more? The answer is yes, but it’s nowhere near the increase in calories that you’re eating.

Does it come close to even matching the amount of calories that you expended? Two other things that I learned. The worst thing that you can do for your appetite regulation is to be sedentary. You lose your reg, your appetite regulation. So you’re you don’t know when to stop eating even when you’re full.

And then you become hungry much sooner than when you should. The thing that sent that tends to regulate your appetite the best is a moderate amount of exercise. It causes you to stop eating and like towards the end of a meal when you’re full. And it causes you to feel fuller in between meals longer.

So exercise is, again, I didn’t know this before. I don’t spend my time on aerobic exercise focus. I’m a resistance training guy. But after going in all of these different directions, I was like, Wow, aerobic exercise isn’t only a great stimulus for fat loss. It helps with not being hungry all the time.

So the study that I found, and this was a recent publication, maybe within the last two years, they actually formulated, again, this is with math, mathematical modeling. Based on original data, they suggested that the the trade off between the increase in appetite and the increase in food intake was about 28%.

So you are going to increase your calories from aerobic exercise, but only by only up to 28% of the additional calories that you’re expending from the exercise. So you’re still in the positive 70, about 70%. And again if it were true that you’re gonna overeat from this aerobic exercise, then we wouldn’t have any data that shows that you lose any fat.

It wouldn’t exist. Now they counter argument to that is, I always love how you’ve impressed upon me always attack, what would the attack on me be? . 

Mike: I think it’s that a, it’s a good exercise to, 

Bill: it’s an awesome exercise and I really appreciate you for this. Yes. The studies are never three years long.

They’re not two years long. 20 weeks, 26 weeks, half a year, 12 weeks. So let’s say this is, now I’m gonna take this full circle. Okay. I’ll even give you that. If you did continue to exercise, maybe you get to where you’re over you’re not getting a benefit. But that goes back to my two week study.

I think there’s a benefit. It helps explain, or it helps counter this constrained energy expenditure model. If you only go into it in very short spurts, there’s, nobody makes an argument that the model exists in the first week or two of dieting. It’s always after a period of time, plus your motivation is high.

So plus your metabolism hasn’t been suppressed too much yet. So I think there’s a lot of reasons to be more aggressive in short amounts of time. And that’s, again, that’s gonna, that’s gonna be the directive of my lab in the 

Mike: future. It’s interesting because early on the general approach that made the most sense to me was along these lines, not this aggressive because I didn’t wanna recommend, especially think of, 3, 4, 5, 6 years ago, and at least the research that I could find, I didn’t feel comfortable telling people to do what we’re talking about here.

But my recommendation, what made sense to me is unless you are again, a competitive bodybuilder and especially a natural one who needs to spend six months getting, strided, glutes then what makes sense for most of us is be aggressive, but don’t be reckless. But let’s just get it over with basically as quickly as we can.

And let’s use diet breaks and refeeds. Let’s use little things, high protein intake. Let’s limit our cardio. Let’s make sure we get enough sleep. Let’s do what we can to make it as. Maybe enjoyable is too generous of a word, but at least as painless as possible. But let’s let’s lose that fat quickly so we can get back to building muscle or minimally get back to maintenance, right?

As opposed to let’s cut the rate of fat loss in half. And so let’s make this thing take twice as long this fat loss phase, and unfortunately, It’s not going to make it twice as enjoyable or it’s not gonna cut the pain quote unquote necessarily by 50%. Unfortunately, calorie restriction is funny like that, right?

Where Yeah. Anyways, it’s just it’s a neat study them, I’m glad you did it and I’m very curious to see the results in your follow up studies. Question for you regarding the training. Cuz people listening maybe wondering how were the people training generally?

And you can in, in this study of yours and if you wanna, if there were a lot of different training programs, cause people were just following their normal program, was there like an hours per week? Were they doing on average maybe three hours of lifting per week five? Was there any cardio.

Bill: Yeah. And let me also, before I forget Alex Brooks and Jack Quinn were my study coordinators for this study. So they managed all of the laboratory supervision stuff. I have a very large research team, so I wanna make sure I give them credit. Based on my memory the frequency of training was three to five days per week on average.

Okay. I think 

Mike: it that’s your normal weightlifting, frequency. 

Bill: Yeah. For cardio, I think it was the, if you were doing cardio before you continued doing the same cardio, and obviously we didn’t supervise that. Yep. So the only intervention that we wanted to introduce was low calorie.

High protein, every, everything about the other parts of their life and their world shouldn’t, hopefully didn’t change. And some of these people were already eating high protein but they weren’t eating high protein at those level, at that low of calories, obviously. 

Mike: How was compliance, how did the people do on average with it and how did they report that they felt, I’m sure some people listening are wondering, were they suffering through their final several days or their final week?

Yeah. 

Bill: I’m trying to, I don’t remember the exact number that dropped out. I’m just trying, I’m looking at my spreadsheet because I made them all red who dropped out? So I think approximately four out of 14. So what is that? About a third of the people quit, which is, I think that’s very typical. It’s very typical for my research in my weight loss studies.

About a third of the people, and by the way, people don’t like dieting and they don’t like lifting weights at the same level that they were doing before when they are dieting. Yep. Plus we have early morning testing, so there’s a lot of reasons for people quitting, but I would say if I were to estimate about a third of the subjects dropped out, Yeah.

Probably a little, probably just a little bit less than that. Yep. What was your other question? 

Mike: It was Oh, how did they feel? How did they feel? Yeah. How did it go for them? Like by the end was, 

Bill: Yeah, we didn’t, we did, and I didn’t analyze this data yet. We did a hunger questionnaire and I haven’t analyzed that yet.

Okay. I went through the protocol myself, so I’ll speak for myself. Yeah. Now, again, I’m highly motivated because this is research that I, that I was asking other people to do. And I usually I always try to put myself through whatever I’m gonna ask subjects so I can relate. And by the way, my wife did the study as well, so I’ll speak for two of us.

And it wasn’t as, my fear of this did not match the reality of this, which I think that’s often the case with dieting. It was hard. My family has a, I don’t wanna say an addiction, but we have the habit of going out to eat on Saturday night and getting pizza after church on Sunday. So that’s just what we do as a family.

And of course, this was Covid. So instead of going out to eat, we were bringing in food so that, that weekend. That was, it was like, ooh. So we had to be very, we had to alter what we normally do for that. I do remember that my 

Mike: wife, which it’s just annoying on principle, like I have a similar, So Fridays I go and get sushi with my family, and then Uhhuh, I make I make pasta for us on Sunday.

So I understand where it’s a little bit annoying. Like I don’t wanna change my routine. I like my routine . 

Bill: Yes. Yeah. But fortunately my wife is she was on board too, so Yeah. So that asides, Yeah. But me and my wife were probably the oldest people that went through this. So the younger people maybe they just, Yep, it’s no big deal.

But again, you get, third of, nearly a third of the people that quit, obviously they didn’t like it or something was going on with 

Mike: them. And how was it for you? How did you feel physically? By the end. I 

Bill: remember just getting my food, like it was a lot of tuna. I ha like I had, I could put a little bit of mayonnaise, a little bit of mozzarella cheese, two cans of tuna or three cans of tuna.

I don’t remember what it was. I remember the foods. I did a post on this where I posted everything and I didn’t need any, hardly any vegetables. And I probably should have during this. I just remember getting food chain. Where’s your vegetables? You, nutrition researcher. 

Mike: Yeah, two weeks. . Yeah, two weeks.

I took a multivitamin. Good enough for two weeks . 

Bill: Not to say I shouldn’t eat more vegetables, but I definitely been during this time. Yeah I don’t I definitely was not miserable. Now if you take away my diet, Dr. Pepper, I probably would’ve been miserable. Like I really rely on diets.

Diet. So diet doctor, that should be a sponsor first. As much as I talk about that , that really helps my hunger for whatever reason. That curves my hunger. So that I relied on that. 

Mike: That could be an interesting follow up podcast because that would be considered controversial to some people. Cuz there are a lot of people in the, just the health space and the fitness space who they would say that that because it’s artificially sweetened that diet soda is worse for you than sugar, sweetened soda. But yeah. Which I don’t agree with but that could be an interesting discussion.

Cause I’m sure some people they were like, Oh wow. Dr. I’m a scientist. He’s saying it’s okay, I can drink a diet pepper when I’m cutting. Oh, wow. . 

Bill: I wouldn’t, what I would say is I do that, 

Mike: but sure. Then okay, fine. Sure. I’ll rephrase that. That that you do, that might be as even just a surprise and people are thinking now, Okay.

Maybe that would help me too. And I understand. I don’t drink soda, but I do understand is it’s just the sweet and it’s just something that’s nice to have when you’re not eating a lot of food, yeah. 

Bill: Yeah. And again, for me, whether it’s the caffeine, there’s not a lot of caffeine in it, but it, for whatever reason, it helps my hunger.

But it is interesting, and again, I’m not an ex don’t research this. Someday I’d like to dump, jump into that research. , but I drink diet soda, my wife does. I don’t allow my children. Not that they don’t need anything with sweeteners, I’m just saying. If they’re gonna drink soda, and I want them to make that decision when they’re 18, which I mean, back to Legion Protein supplements.

My, my children take your protein. I feel good about giving them that. There’s no artificial sweeteners in that and that they’re like, Oh, I get to be like mommy and daddy now I get them 

Mike: my protein. I say my kids that sometimes they’ll wanna mix a little protein powder with milk.

It’s cute. , 

Bill: Hey, protein’s, a lot of benefit. 

Mike: Yeah. That my, my kids mean, not surprising, but I’m sure is years are the same. They’ve been eating a high not inappropriately high, but certainly higher than the average kid, even that. So we make sure to give ’em a serving of protein at lunch and dinner.

And then when they wanna snack, sometimes they’ll grab, like we have high protein yogurt, so like skier yogurt, for example, the Icelandic version of the Greek yogurt craze. . And so they’ll grab that or maybe they’ll drink some milk. And so they get, on average probably two or three servings that appropriate for small bodies of protein per day.

And I’m happy that is in place because it matters, it, that, that is, that’s helping their bodies develop. Better for sure. 

Bill: Yes. And there’s that protein leverage theory, so maybe that helps regulate their appetites better. And I’m, I have two daughters, so I’m very, again, not an expert in this area, but I’m very sensitive to potential eating disorders.

Yeah. So I don’t like to say off limit. So again, if they want a soda when we go out to eat, have a nothing wrong with that. Yep. I do 

Mike: one thing, I let ’em have a dessert every day if they want. They’re just, I get ’em a hundred calorie desserts. So maybe it’s a serving size. Yes, 

Bill: exactly. That’s the key I.

Yeah I would say my, again, by no means is my household. No, I don’t 

Mike: explain the calories. I don’t want them to get wrapped up in that. But those, what’s what it is? It’s a hundred calorie little fudge bar. They could pick that or a hundred calorie strawberry ice bar thing, or, but they’re a hundred calories as opposed to 300 calorie desserts.

That’s not appropriate for my four year old daughter. You know what I mean? No. 

Bill: Or just not having a bowl to put your snack in eating outta the bag. Like it’s yeah, just like you, I’d love to have the time to to actually speak from a place of authority, but it makes sense to me.

Mike: Totally. Totally. So anyway, coming back to this study. So let’s see. Those were the major questions that, that I had. And I guess for, oh, sorry, there wasn’t one other question and that is, what are your thoughts in terms of, let’s say it’s two weeks to, to four weeks, let’s say that people listening the reason that they may want to go longer than two weeks is to get a bit more fat loss out of it.

And let’s say they’re two weeks in and they’re feeling pretty good. Yeah, they’re a little bit hungry from time to time, but their workouts are still pretty good. And they’re there, there doesn’t seem to be any major issue and they’re like, Ah, alright, I’ll go another week, or maybe I’ll even be able to go two more weeks.

What are your thoughts in terms of where you would implement. In the overall scheme of a fat loss phase, for example, start with it or end with it, or we already talked about this, intermittent or just, now and then use of two to four weeks, and that’s one way to use it. But let’s say somebody has, for example, let’s say somebody has a lot of fat to lose and it wouldn’t really make sense for them to be aggressive every two months or every one month.

Like they really need to start with losing a lot of fat. Something that I’ve talked about is. This person, they can get away with a larger deficit, obviously, without really any negative side effects. But I know in working with people over the years who have a lot of fat to lose, sometimes they find it motivating to start aggressively because they see quick results and they see big results.

And that just helps them get momentum and and then go to something that’s a bit more sustainable because they do have, maybe several months of it doesn’t have to be of course, continuous restriction, but they have several months of dieting ahead of them versus maybe somebody who maybe they don’t have that much fat to lose.

Do you think it would ever make sense for them to maybe end their cut with a final h. Or something else together? I think 

Bill: what I would start with if they have the motivation at the end of their diet to do that , or if they’re more inclined to do that, great. I don’t think that would ex, I don’t think that would be the case for most people.

I know you, 

Mike: You get close to the finish line on a, on, even on a work project. I’ve experienced that where well, that’s true. Motivated, and then you get into the dip and then you’re just slogging through it and you just, you try not to look at how much you still have in front of you.

You maybe you try to look at how much you’ve already gotten done just to keep yourself in good spirits. But then as you get toward the end and that you see that finish line, you can get a resurgence of motivation. Yeah. Maybe 

Bill: that’s the next study. We do a two week. Heavy or severe deficit on the first two weeks versus a heavy on the last two weeks.

I’m, I assume that you’re more motivated at the beginning, so I would at 

Mike: least, and I would agree with that. I would 

Bill: agree with that. Yeah. And then maybe tail, taper out of it. But yeah. At the end of the day, I don’t think it matters if you’re, whatever your caloric deficit was at the end of your period, whatever your fat loss phase was, I would say it’s all the same if your caloric deficit was the same, I think it’s just a matter of trying to match that caloric deficit with what you’re more likely to execute on.

Mike: Yeah. Yeah. That makes sense. And I don’t know if it would, Makes sense to, to scale up to an aggressive middle of a cut and then come down from there. I would tend to agree with you that in most people starting aggressively it would probably make the most sense. And then and then bringing it down into something, again, it’s more sustainable for the remainder, but given the timeframe that, that we’re looking at, a lot of people, if they don’t have that much fat to lose, they have maybe eight to 10 weeks of, let’s say, of cutting and that’s eight to 10 weeks of, 20, 25% deficit.

So they can shave some time off of that by starting aggressively. If they could get in as a good two to even four weeks of aggressive fat loss to start, that can make a big difference in terms of the total duration. Yeah. Yeah. 

Bill: And I think. My research would give people a sense of validity to this approach as long as protein is high and as long as your resistance training.

Mike: Awesome. Thanks again for taking the time to do this. So those are all the questions I had. This was super informative. And let’s wrap up with where people can find you in your work. I know you have a new ebook that just came out and let’s definitely make sure people know about that.

And then if there are any other new and exciting things that you have coming that you want to tell people about I, I don’t know if you’re ready to announce any of them. Let’s also, let’s do that now too. Yeah, thank you 

Bill: For the opportunity. So I did write a guidebook. It’s called Building Your Ultimate Body, and it’s basically just my philosophies on basically living a, what I call a physique lifestyle or like a recreational body builder.

So we talk about fat loss phases, just like what we talked about here. There’s also an entire section on resistance training. I talk about like load effort, frequency, intensity all of those things. And the idea is to. Your lifestyle to fit my, the program to your lifestyle. So rather than give you this program, follow this program, what’s your lifestyle?

What can you commit to? Now here’s the best way to do this with your nutrition and with your resistance exercise. Now there are two assumptions that you’re gonna lift weights and that you’re gonna eat higher protein. So tho those are assumptions that I don’t really Table stakes. . Yes. Yes. If you’re interested, if you just go to my Instagram page, it’s at Bill Campbell PhD.

Just go to the link in my bio and it takes you right to the sales page. And in terms of following my work, I’m only on one in one place. That’s Instagram. So I try to educate people mostly on dieting to some extent, sports nutrition stuff. So at Bill Campbell, PhD is where you get what I’m working on in my lab or just my education on this fitness lifestyle approach that I’ve essentially dedicated my life to, as have you.

Mike: Yeah. And a great account to, to follow, like anybody still listening you probably liked this interview. You’re gonna Bill’s Instagram account just because again, a lot of great educational information very practical, very easy to understand that. That’s my kind of stuff, yeah. Me too. . Yeah. Yeah. Thanks again, Bill, for taking time to, to do this and we should line up the next one. I know we had also on a, on our agenda for today there, there’s another study that Bill did regarding flexible dieting, and I didn’t know if we were gonna get to it. I had a feeling that we wouldn’t, that we would have a lot to talk about just on the rapid fat loss.

And so let’s do that in the next one, unless something even better comes along in the interim, yes, 

Bill: that sounds great. I’m looking forward to talk about that study as well. 

Mike: Same. I hope you liked this episode. I hope you found it helpful, and if you did subscribe to the show because it makes sure that you don’t miss new episodes.

And it also helps me because it increases the rankings of the show a little bit, which of course then makes it a little bit more easily found by other people who may like it just as much as you. And if you didn’t like something about this episode or about the show in general, or if you have ideas or suggestions or just feedback to share, shoot me an email, mike muscle for life.com, muscle f or life.com, and let me know what I could do better or just what your thoughts are about maybe what you’d like to see me do in the future.

I read everything myself. I’m always looking for new ideas and constructive feedback. So thanks again for listening to this episode, and I hope to hear from you soon.