It’s estimated that there are over 2+ million scientific papers published each year, and this firehose only seems to intensify.

Even if you narrow your focus to fitness research, it would take several lifetimes to unravel the hairball of studies on nutrition, training, supplementation, and related fields.

This is why my team and I spend thousands of hours each year dissecting and describing scientific studies in articles, podcasts, and books and using the results to formulate our 100% all-natural sports supplements and inform our coaching services. 

And while the principles of proper eating and exercising are simple and somewhat immutable, reviewing new research can reinforce or reshape how we eat, train, and live for the better. 

Thus, each week, I’m going to share three scientific studies on diet, exercise, supplementation, mindset, and lifestyle that will help you gain muscle and strength, lose fat, perform and feel better, live longer, and get and stay healthier. 

This week, you’ll learn whether eating whole eggs helps you build more muscle than eating egg whites, whether HIIT helps you burn more fat than traditional cardio, and whether you should believe the hype about HMB supplements.

Whole eggs may be better for building muscle than egg whites.

Source: “Consumption of whole eggs promotes greater stimulation of postexercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men” published on October 4, 2017 in The American Journal of Clinical Nutrition.

Among fitness-minded folks, it’s become common to avoid whole eggs in favor of egg whites to save calories, increase your protein intake, and reduce your cholesterol intake.

This study shows that if you want to build muscle, though, you should probably eat the yolk. 

Scientists at the University of Toronto had 10 young men do a leg workout consisting of 4 sets of 10 reps of the leg extension and leg press, then they split the participants into 2 groups:

  1. One group ate 3 whole eggs immediately after the workout.
  2. The other group ate an equivalent amount of protein (18 grams) from egg whites immediately after the workout.

Once the participants had finished their meals, the researchers used several tests to measure how much each meal elevated muscle protein synthesis (MPS).

Seven days later, both groups returned to the lab, but switched places—those who ate whole eggs the first time ate egg whites and vice versa.

The results showed that those who ate whole eggs increased MPS rates ~2.7 fold above baseline, whereas the egg-white group only increased MPS rates ~1.9 fold. Here’s a graph illustrating this:

Whole Eggs vs. Egg Whites

Why would whole eggs be more anabolic than egg whites?

The researchers weren’t sure, though they offered a few plausible explanations: 

1. It could be that the extra calories from whole eggs increased MPS.

The whole eggs contained 226 calories, whereas the egg whites only contained 73 calories, and eating more calories is one way to keep MPS elevated. That’s probably not what’s going on here, though.

A similar study found that drinking the same number of calories from whole milk caused a larger increase in protein synthesis than skim milk, despite consuming less protein, so the difference in MPS probably can’t be explained just by the difference in calorie intake.

2. It could be that the cholesterol content of the egg yolks increased MPS.

Some data shows that people who consume more cholesterol build more muscle than those who eat less. Cholesterol is involved in the production of testosterone and other muscle-building hormones and improves cellular signaling related to muscle growth, which may partly explain the difference. 

That said, it’s still not clear how anabolic cholesterol really is, and it seems unlikely muscle protein synthesis would spike within a few hours of eating it. 

3. It could be that the vitamins, minerals, and unique fatty acids like phosphatidic acid, arachidonic acid, palmitic acid, and DHA in eggs promote muscle growth.

For example, some studies show that arachidonic acid supplementation affects gene expression related to muscle growth, but with a dose twice as high as what these guys were getting from eggs.

Or, it could be some synergistic combination of all three effects—right now we just don’t know.

And while we do know that eating whole eggs increased MPS more than egg whites, transient jolts in MPS don’t always translate into more muscle gain over time. For example, at least in beginners, the rise in MPS that occurs over the 6 hours after a workout isn’t correlated with how much muscle they build during a 16-week training program.

At the very least, this study shows that you probably don’t need to make your post-workout meal zero or low-fat—the extra fat in the yolks didn’t interfere with MPS one iota. 

When it comes to your post-workout meal, your number one priority is to eat enough protein—around 30-to-40 grams is a good rule of thumb. After that, ensure it’s a high-quality protein source rich in leucine, like whey or casein protein powder, meat, poultry, or seafood. Once those two things are in place, what else you do is less critical.

And if you want a clean, convenient, and delicious source of protein, try Whey+ or Casein+.

(Or if you aren’t sure if Whey+ or Casein+. is right for you or if another supplement might be a better fit for your budget, circumstances, and goals, then take the Legion Supplement Finder Quiz! In less than a minute, it’ll tell you exactly what supplements are right for you. Click here to check it out.)

TL;DR: Whole eggs raise protein synthesis rates more than egg whites post-workout, though it’s not clear if this leads to more muscle gain over time.

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HIIT is not better than low- or moderate-intensity cardio for fat loss.

Source: “Excess Postexercise Oxygen Consumption After High-Intensity and Sprint Interval Exercise, and Continuous Steady-State Exercise” published in November 2016 in The Journal of Strength & Conditioning Research.

Books, courses, websites, and even brick-and-mortar fitness franchises have been built on the idea that high-intensity interval training (HIIT) is the best way to burn fat.

It turns out that the supposed supremacy of HIIT over traditional cardio is a mirage. 

One of the strongest repudiations of this idea is a study conducted by scientists at Arizona State University. The researchers had 10 college-age men complete three different workouts on different occasions: 

  1. A HIIT workout involving four 4-minute intervals with 3 minutes of low-intensity exercise between each.
  2. A sprint-interval workout involving six 30-second sprints with 4 minutes of low-intensity exercise between each.
  3. A MISS (moderate-intensity steady state) workout involving 30 minutes of moderate-intensity exercise at 80% of maximum heart rate.

They found that the sprint-interval workout increased excess post-exercise oxygen consumption (EPOC, which is the number of calories burned after the workout) the most—burning about 110 calories over the next 3 hours. HIIT came in second, burning 83 calories after the workout thanks to EPOC, and MISS cardio came in last, burning just 64 calories. 

The first thing that should strike you about these results is how few calories EPOC burned.

Both kinds of interval training only burned about 100 calories from EPOC—not enough to significantly impact fat loss. Most of these calories were also burned in the first hour after exercise, which indicates that EPOC tapers quickly after the workout—it doesn’t “supercharge” your metabolism the rest of the day. 

When the scientists totted up how many calories the subjects had burned both during their workouts and due to EPOC, they found that the “boring” MISS workout burned the most. Specifically, the participants burned 348 calories with MISS cardio, 329 calories with HIIT, and just 271 calories with sprint-interval training. 

It’s worth noting that the MISS workout was slightly longer than the other two, but only by about 7 minutes. You could also argue that 80% of maximum heart rate is a bit harder than most people push themselves during MISS cardio, but no matter how you look at the results, it’s hard to argue that HIIT was superior. 

In other words, you burn about the same number of calories per minute during a MISS workout as you do during a high-intensity interval workout—HIIT isn’t a more time-efficient way to burn calories.

While this may sound strange, it makes sense when you run the numbers. During a high-intensity or sprint-interval workout, you aren’t exercising at a high intensity for very long.

The actual high-intensity intervals burn a lot of calories, but the rest intervals don’t, and when you average the two, you end up burning about as many calories as you would have just maintaining a moderate intensity for the same duration. 

A subsequent review published in Obesity Reviews bolstered this study’s results, too. It analyzed 31 studies involving 873 participants and found that people doing HIIT, sprint-interval, or MISS cardio lost about the same amount of weight. 

So, what’s the best kind of cardio for weight loss? 

Whatever you enjoy.

Just be aware that HIIT is more taxing on the body than most MISS cardio. As a result, it’s more likely to interfere with your weightlifting workouts when done more than a few times per week. Thus, a good rule of thumb for those who prefer HIIT but also like to lift weights is to do a maximum of two HIIT workouts per week and supplement with 1-to-2 MISS workouts if necessary. 

(Fun fact: Research shows that you’ll improve endurance more if you use a combination of HIIT and MISS workouts than if you do either in isolation.)

And if you’d like even more specific advice about which types of training you should do to reach your health and fitness goals, take the Legion Strength Training Quiz, and in less than a minute, you’ll know the perfect strength training program for you. Click here to check it out.

TL;DR: High-intensity interval training doesn’t actually burn more calories or fat than traditional, moderate-intensity, steady state cardio, so you should do whichever you prefer more. 

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HMB isn’t better than steroids for building muscle. 

Source: “The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study” published on March 6, 2014 in European Journal of Applied Physiology.

“HMB is better than steroids.” 

That’s the conclusion you’d draw from the results of a 2014 study conducted by scientists at The University of Tampa, if you took their research at face value. 

The study (supposedly) showed that supplementing with beta-Hydroxy beta-methylbutyric acid (HMB), a substance formed when your body metabolizes leucine, caused more muscle growth than what you’d expect from steroids like testosterone.

Since then, supplement companies have peddled HMB as a fitness factotum, capable of boosting muscle growth, endurance, recovery, and power output, and decreasing muscle breakdown.

Can you trust these results, though?

The researchers had 20 experienced male weightlifters complete a well-designed 12-week weightlifting program. Eleven of the weightlifters supplemented with 1 gram of HMB three times a day (3 grams total), taking the first dose 30 minutes before exercise (in the morning) and the other two at midday and with their evening meal. On non-training days they took the three doses with three different meals.

The other 9 weightlifters took a placebo using the same dosing schedule.

Both groups followed the same diet, consisting of 25% protein, 25% fat, and 50% carbohydrate.

The results showed that the HMB group knocked the starch out of the placebo group when it came to strength, power, and body composition.

Here’s what the numbers looked like for strength and power:

  • Squat: +25.1% for the HMB group vs. +5% for the placebo group
  • Bench press: +11.3% vs. +3.3%
  • Deadlift: +16.5% vs. +8.2%
  • Wingate peak power (cycling): +18% vs.+11.7%
  • Vertical jump power: +20.2% vs. +12%

And here’s how their body composition changed:

  • Muscle mass: +16 pounds vs. +5 pounds
  • Fat mass: -12 pounds vs. -4 pounds
  • Quad thickness: +14.3% vs. +4.7%

The HMB group also experienced a decrease in cortisol, creatine kinase, and  3-methylhistidine:creatinine ratio, which are all signs of improved recovery.

Lastly, as the training program progressed and the workouts got harder, the HMB group continued to get progressively stronger, whereas the placebo group’s performance dipped.

These results show that supplementing with HMB for 12 weeks results in . . .

  • 16 pounds of muscle gain in men who were already muscular
  • 12 pounds of fat loss in men who were already lean
  • A 25% increase in squat strength, a 16% increase in deadlift strength, and a 12% increase in bench press strength in men who were already strong

To put these numbers into perspective, studies show that people using steroids and lifting weights will gain an average of ~10 pounds of muscle in 12 weeks, making HMB more effective than steroids, according to these results.

Aside from the sheer magnitude of the results, there are a few more reasons to raise your eyebrows at this study:

  • It was partially funded by Metabolic Technologies Inc., which holds the patent on the HMB supplement used.
  • Three authors are employees of the aforementioned company, and all three were involved in the study design and manuscript preparation.
  • The rationale for these astounding benefits was that the type of HMB used in the study is absorbed faster than previously researched (and much less effective) forms of HMB, but there’s little reason to think absorption rate would explain these results.
  • All other previous studies showed that HMB did little to boost strength and improve body composition in experienced weightlifters.

. . . all of which made many people question the study’s credibility.

Suspicions about its validity only increased two years later, when the same research team conducted a similar study and reported equally outlandish results.

At that point, swathes of researchers cosigned three separate letters addressed to the relevant journal editors highlighting their concerns about the integrity of both studies. 

(One of these letters spurred a response from the scientists at The University of Tampa in which they explained that there were no issues with the data they reported, rather that everyone else had misunderstood.)

Still, until researchers from other labs replicate these studies and arrive at different findings, it’s difficult to say for certain that these studies were rigged. However, it seems highly plausible, especially since relatively similar (though far from identical) subsequent research shows HMB to be a dud. 

That said, HMB does have one bona fide benefit: preventing muscle breakdown.

Research shows that HMB may slow the rate at which your body breaks down proteins, which means taking HMB before fasted training could help you to reap the fat loss benefits of fasted exercise while mitigating muscle loss.

(Check out this article to learn more about the pros and cons of fasted exercise.)

That’s why we included 2.5 grams of HMB in our pre-workout fat burner, Forge.

(And again, if you aren’t sure if Forge is right for you, then take the Legion Supplement Finder Quiz! In less than a minute, it’ll tell you exactly what supplements are right for you. Click here to check it out.)

TL;DR: Studies that seem to show HMB is “better than steroids” were almost certainly biased, and there’s little to no evidence that HMB will help you gain muscle or strength, recover faster from workouts, or lose fat.

+ Scientific References