If you want to lose fat or gain muscle, then you need to know how many calories you burn every day.
If you don’t, it’s going to be a lot harder than it should be, if not impossible.
But if you’re here, that’s probably not news to you. (And if you don’t, read this article first and come back.)
You just aren’t sure how to actually do it – how to easily and accurately calculate how many calories you’re burning.
You’ve probably also poked around for an answer already and discovered that you have quite a few options.
Mathematical formulas, fitness and activity trackers, workout machine readouts, and so on.
Which can you rely on, though? Which will be best for you?
Well, that’s what you’re going to learn in this podcast.
By the end, you’ll understand which methods of calculating calories burned work, which don’t, and which are the simplest and most practical.
3:48 – How do scientists measure energy expenditure?
11:41 – How accurate are the calorie readouts on workout machines?
15:31 – How can you figure out how many calories you’re burning through exercise?
20:46 – How can you figure out how many calories you burn every day?
Mentioned on the Show:
[00:00:01] Hello. Welcome to another Muscle For Life podcast. I am Mike Matthews, of course. And this one is about calorie burning. How many calories do really burn every day? Now, that’s important, as you probably know, because if you want to lose fat or gain muscle, then you got to know this.
You got to know approximately how many calories you’re burning every day, because if you don’t, it’s going to be a lot harder than it should be, if not impossible. But if you are here listening to this podcast, that is probably not news to you. Rather, you probably just aren’t quite sure how to do it, how to easily and accurately calculate how many calories you are burning.
And I’m going to guess that you’ve poked around on the interwebs for an answer already, and you’ve discovered that you have quite a few options. You have mathematical formulas, you have fitness and activity trackers, you have workout machine readouts, and so on.
And you’ve probably also discovered that some of these methods are simpler than others and some of them contradict others. And so you might be wondering which you can rely on, which is going to be the best for you and which is ultimately going to produce results, because that’s what it’s all about. Right? And that’s what you’re going to learn about in this podcast.
By the end of it, you are going to understand which methods of calculating calories burned work, which do not, and which are the simplest and most practical ways of going about it.
[00:03:30] All righty, let’s start this discussion with how scientists measure energy expenditure. And yes, energy expenditure – that’s the key here, because when we’re talking about burning calories, what we are really talking about is burning energy. And if you didn’t know that, then I recommend you pause this podcast and look up the podcast that I recorded on energy balance.
If you search my feed, you’ll find it. Listen to that and then come back and listen to this one. It will make more sense if you understand energy balance, which is the relationship between the amount of energy you are burning and you are eating.
[00:04:05] So the gold standard, scientifically speaking, for measuring energy expenditure is a method called indirect calorimetry. And this involves measuring the amounts of oxygen and carbon dioxide that you inhale and exhale – and from this, calculating your energy expenditure.
And this method is very accurate because there is a direct relationship between how your body uses these gases and how much energy it is burning moment to moment. And the reason there is a relationship there is your cells need both oxygen and carbon dioxide to create energy, which is why you need to breathe to stay alive.
And only small amounts of oil you inhale are used for energy generation, though. Most of the gases are exhaled. And how much of the oxygen and carbon dioxide are exhaled depends on how much energy is needed. So the greater the energy demand at any moment, the greater the need for these gases.
And therefore, the difference between how much of each of these gases are inhaled versus exhaled is a reliable yardstick for energy production. So the less of these gases that’s exhaled, the greater the energy production. And this is what scientists eventually figured out and they figure out how to measure it and how to quantify it. And the result is this indirect calorimetry.
[00:05:30] Another way that scientists can accurately measure energy expenditure is with something called doubly labeled water. And this involves drinking water that contains special compounds that stay in the body. And then researchers measure the rate at which these chemicals are eliminated through sweat, saliva, and urine.
And they use that data to compute your metabolic rate. And how this basically works is the more energy you are burning, the faster these chemicals move through your system.
[00:05:58] Now, those methods, again, are very accurate. They’re very scientific. They have a lot of research behind them. But the downsides are obvious. They require access to specialists with special equipment and they are expensive.
I highly doubt you’d be interested in making multiple trips to a lab and spending a number of hours and hundreds, if not thousands of dollars to just figure out how many calories you’re burning. You need something that’s simpler. You need something that’s more affordable.
[00:06:30] And that’s why many people turn to activity trackers, to fitness trackers. And these devices are definitely convenient. But how accurate are they? Pitch sounds great. All you gotta do is wear this stylish little band and do your thing throughout the day and voilà, you’ll know exactly how many calories you’re burning.
Well, unfortunately, studies show that these devices are not nearly as precise as we’re being told. So fitness trackers contain an accelerometer, which is an instrument that registers the velocity of different movements. So every time you take a step, this accelerometer wiggles and it produces some raw data that is run through an algorithm that then is supposed to be able to estimate how many calories that movement burned.
You add these things up throughout the day and you add them on top of a basal metabolic rate and there you go – total calories burned. Now, the main problem is most of these devices can only be calibrated for one specific kind of activity. And doing anything else produces inaccurate data.
[00:07:31] For example, most pedometers, which are devices that record the amount of steps that you take so you can estimate the distance traveled over a given period of time. Most of these devices are only good at measuring the calories you burn from walking, of course, but also walking at a certain pace. If you walk faster or slower, these devices become less accurate.
Studies have shown that. And they’re even less accurate for running. And they are completely useless for something like weightlifting. Because squatting, for example, can burn a lot of energy, but it does not actually involve that much physical motion. It involves a lot less motion than a leisurely walk, for example, but burns a lot more calories per minute or per second, however you want to look at it.
[00:08:16] And two very popular fitness trackers out there are the Fitbit family and the Jawbone. At least it was, the Jawbone may not be popular now, it was popular a couple of years ago. And it was reviewed in a 2015 study which found that when used per the instructions, both of these devices measured energy expenditure fairly accurately, but tended to underestimate the calories burned.
So the bottom line here is fitness trackers can give you a ballpark number of the calories that you’re burning, but not the exact and not even necessarily a close to exact number. And studies on other types of activity trackers like pedometers have found the same thing as well. These devices are okay at estimating the average number of calories you are burning for a particular activity, like walking or swimming or biking. But they are not good for measuring much else. They can be off by 50 percent or more.
[00:09:19] We also have some smartphone options these days. You have apps that are advertised as “even more accurate and convenient than these dedicated fitness trackers” that you have to wear on your body. And the data says otherwise, though. Research shows that the energy expenditure measurements produced by many smartphone fitness apps are off by 30 to 50 percent.
And then there are fitness trackers that use your heart rate to estimate the number of calories that you are burning and as your heart rate is directly correlated with your energy expenditure. These types of devices do tend to be more accurate than the others that we’ve discussed. And especially if they account for your body weight age and your resting heart rate.
The problem, though, is the most accurate of these types of gizmos require that you wear a strap around your chest to measure your heart rate accurately. And it’s a bit unwieldy. The ones that measure your heart rate via the wrist generally produce inferior results.
[00:10:14] So the bottom line here is fitness and activity trackers can give you a rough estimate of how many calories you’re burning through exercise in particular and other types of physical activity. But it’s not a highly accurate measurement. It is not consistently and reliably accurate enough to determine your calorie intake based on your goals.
It may come out okay, but chances are for most people it’s going to produce an inaccurate number that will then lead to maybe eating too much based on your goals or too little. And that, of course, can lead to not just a lack of results, but other problems as well.
[00:10:54] In terms of, like if you are eating far too little, if you are underestimating your calorie burn and then you are creating your calorie deficit – let’s say 20 to 25 percent based on the number that you’ve estimated, and if that’s actually like, let’s say, a 35 percent calorie deficit – that is going to be rough. You are not going to feel good. Sure, you’re going to lose fat, but you’re also probably gonna start losing muscle, and your energy levels are going to plummet, and it is not going to be a good time.
[00:11:23] All right. Let’s talk about workout machines. How accurate are the calorie readouts on these machines? Now, many people, when they go into their cardio workouts, they have a target for the number of calories they want to burn, which makes sense. And they rely on the machine readouts to know when they’ve achieved their goal and they can end their workout.
Unfortunately, most these machines overestimate the number of calories that you are burning in your workouts and by a lot. Which is not surprising. Me thinks that’s probably not a mistake because it is definitely encouraging to see a big number and makes you want to keep using the machine.
[00:12:00] A good case in point here is a study that was conducted by researchers at the University of California, San Francisco’s Human Performance Center. And researchers found that on average, stationary bike schools overestimated calorie expenditure by 7 percent. Stair climbers were over by an average of 12 percent, treadmills 13 percent, and ellipticals by 42 percent.
That’s no good. And there are several reasons for these inaccuracies. One is the algorithms used to estimate calorie expenditure differ from manufacturer to manufacturer. And some of the math is decent and some of it is rather poor. There’s also the fact that weight, age, gender, and fitness level affects how much energy you burn while you exercise.
So when the effort level and the duration are the same, heavier people generally burn more energy than lighter people, which makes sense, of course, they have to move more weight. And fitter people generally burn less than unfit people. And that actually makes sense because as the body adapts to the exercise that you’re doing and becomes fitter, it also becomes more efficient metabolically and it becomes harder and harder to force the body to burn more energy.
Similarly to the phenomenon of it becoming harder and harder to force the body to continue gaining muscle as you become more muscular and you become more experienced as a weight lifter or experience in whatever form of resistance training you are doing as time goes on, it is harder and harder to cause muscle damage.
And the body responds less and less enthusiastically to the muscle damage that does occur in terms of adding new muscle tissue. Anyway, back to the machines. Very few machines ask for information related to weight, age, gender, and fitness level. And instead just work off of fixed data.
[00:13:54] Another factor that impacts energy expenditure machines is wear and tear. For example, the belts on treadmills and other machines tend to slip with age, and that reduces the amount of resistance they provide. And it makes them easier to use and thus less effective for calorie burning.
[00:14:13] And then there’s user error. That’s also a factor with the most common mistake being heavily leaning on the handrails, on a stair stepper, or an elliptical, or a treadmill. And especially when walking on an incline. By doing this, what you are doing is you are lessening the amount of weight that your muscles have to move.
And that, of course, reduces the energy cost of the exercise. Another example of user error is being passive with your upper body on the elliptical machine. And the calorie calculations on these machines assume that you’re going to be vigorously pumping your arms along with your legs. So if your arms are up there just along for the ride, the read out is going to be very wrong. And that helps explain why, in the study I just mentioned, the elliptical machines overestimated calorie expenditure by 42 percent on average.
[00:15:01] So if scientific tests are inconvenient and expensive and fitness and activity trackers and workout machines are kind of hinky, what is the best solution here?
[00:16:48] How can you figure out how many calories you’re burning through exercise and other physical activity? Which, of course, you need to know to be able to calculate how many calories you’re burning every day? Because, again, you have your basal metabolic rate, which is the amount of energy that it costs to simply remain alive.
If you were to sit in bed all day and literally not move, it would still cost a fair amount of energy to keep all of your organs working and keep everything going. And that amount of energy would be your basal metabolic rate. You take that, you add in all the energy burned through physical activity. And there is your total daily energy expenditure. But how do you get there?
[00:17:20] Well, the easiest method that is very accurate is a system based on what’s called a metabolic equivalent of [00:17:31] task or MET. So think of an MET like a calorie, but instead of measuring the amount of energy that is required to heat one kilogram of water, one degree Celsius, which is the amount of energy that is contained in a calorie.
At least when we’re speaking about calories and food, which technically are referred to as kilocalories, but we just call on calories. An MET is the amount of energy that an average size person will burn while sitting still for one minute. And different activities are assigned different MET scores.
So walking at a slow pace for a minute, for example, burns about double the amount of energy of sitting still and thus has an MET of two. Vacuuming is on the list of things quantified and as it’s more vigorous than walking at a slow pace, it’s listed at 3.5 MET’s and so on.
[00:18:28] And you can find the MET scores of wide variety of physical activities in The Compendium of Physical Activities Tracking Guide. If you Google that, it will come up. And once you have that guide, here’s how you can use it to figure out how many calories you’re burning.
So the first step is you got to understand the basic MET equations. So the math that is used to determine calorie expenditure here is simple. You have calories burned equals MET’s times your weight in kilograms, times hours of activity. So that is the equation.
[00:19:04] And the second step is to find the MET value for the activity that you want to measure. So let’s take weightlifting, for example, that’s listed at 6 MET’s. And make sure you pay attention to the activity intensity as well, because many activities like walking have more specific entries with different MET scores. So walking up and down stairs, for example, has a higher MET score than strolling around the block.
[00:19:30] So the third step here is you plug the MET value of the activity into the equation. So let’s say that you weigh 80 kilograms or about 175 pounds and you lift weights for one hour and you want to know how many calories did you burn. So here’s the equation then: you have six MET’s, times 80 kilograms, times 1.
So again, that is the weight lifting MET score, which is six, which is an indication of how difficult it is; times your body weight in kilograms, 80 times the duration in hours, which is 1; and you do that math, 6 x 80 = 480. So you burn about 480 calories per hour of weightlifting that you do.
Now, in reality, you are not burning exactly 480 calories per hour, of course. You may be burning a bit more. You may be burning a bit less. But if you’re training, protocol is pretty standard it will average out to about 500 calories per hour.
[00:20:31] Now, if you do multiple types of exercise in a single workout, you can use the same process to calculate each component of the workout and then add those numbers up for the total calorie expenditure of the workout.
[00:20:45] And just to give you a few more examples of how many calories a 175-pound person – and gender here doesn’t matter – would burn while exercising, according to the MET method, walking at two miles per hour – so a slow, leisurely walk – clocks in at about 280 calories per hour, which is fairly significant.
If you can walk several hours per week, for example, you can add up to 1,000 calories burned per week fairly easily. Which is one of the reasons why I recommend walking while cutting. Basically supplementing your energy burn with walking because the calories can add up and it has basically no impact on the body.
It doesn’t cut into recovery or into muscle and strength gain or preservation in the same way that higher intensity forms of cardio do. Now, of course, the higher intensity forms of cardio do burn more energy and burn more fat, but it does come at a cost.
[00:21:42] Anyways. Running at about 6 miles an hour, that’s 800 calories per hour for a 175-pound person swimming at a moderate level of intensity is about 560 calories per hour. And biking at a moderate level of intensity is about 640 calories per hour.
[00:22:00] All right. So that’s calories burned while exercising. Now, let’s zoom out a little bit and talk about calories burned every day. How do you get to this number? And scientists refer to the total number of calories you burn every day as your total daily energy expenditure. You’ve probably heard of that. It also is often referred to as your TDEE.
[00:22:21] So, for example, I’m 34 years old. I’m 6′ 2″ or 6′ 1″, somewhere in between there, 195 pounds, I lift weights about four to five hours a week and I do about an hour of cardio per week, and my TDEE is about 2,800 to 2,900 calories. What that means is, on average, I burn about 2,800 to 2,900 calories per day.
[00:22:46] And I mentioned this earlier, but I’m just going to reiterate it here, that your TDEE is comprised of your basal metabolic rate, plus the additional energy burned through physical activity, and the food that you eat. So let’s review each of these points separately.
[00:23:01] Basal metabolic rate, as I mentioned earlier, is the amount of energy your body burns at rest. This is the minimum amount of energy it costs to stay alive. And when you move your body, that costs energy as well. No matter how large or small, or how long or short an activity is, it burns energy. When you get out of bed in the morning, you’re burning a little bit of energy.
And when you eat food, it costs energy to digest and absorb it. And this is scientifically known as the thermic effect of food or TEF. And research shows that TEF accounts for about 10 percent of total daily energy expenditure. So it’s a significant amount. And that amount varies based mostly on the macronutrient composition of your diet.
A higher protein diet, for example, has a higher TEF score than a lower protein diet. Now, when you sum the energy your body burns to stay alive, you BMR, and the energy burned through your physical activities and the foods that you eat, the digestion and the absorption of those foods, you arrive at your TDEE.
And you can get there by calculating your BMR using a good calculator. And if you want to find a good calculator, just Google “Muscle For Life BMR” and you’ll find an article that I wrote on it that has a calculator. And then you can calculate the energy that you burn through various physical activities using the MET system that I mentioned earlier. And then you increase that sum by 5 to 10 percent for TEF.
[00:24:34] Now that works, but it is a bit of a hassle. It produces a highly accurate TDEE measurement, but it’s a bit of pain in the ass. Fortunately, there is a simpler method that can produce similar results using some very simple math. It’s called the Katch-McArdle formula. And how it works is: you first estimate your BMR and then you multiply it by a number based on how physically active you are.
How many hours of vigorous physical activity you engage in every week. And while I’ve found that the standard multipliers included in the Katch-McArdle formula, which was designed based on metabolic research, tend to be a bit high. They tend to overestimate calorie expenditure. If you dial them down a little bit, which is what I do and I recommend, you can get a pretty accurate estimate of your average total daily energy expenditure.
[00:25:27] For example, my BMR calculation comes out to about 2,100 calories and according to my modified Katch-McArdle activity multiplier, I should multiply that by 1.4 to get my average total daily energy expenditure. And if you do that math, it comes out to 2,940. So about 2,900 calories. And practically speaking, that is correct. If I eat 2,900 calories a day, I maintain my weight.
And of course in actual practice, that means that some days I’m eating slightly more calories than I burn and some days it’s slightly less. But because it evens out over time, because if you look at it in terms of, let’s say, my total calorie expenditure for a week or even for a month, if I eat about 2,900 calories a day, it equals about the amount of energy that I’m burning over a week or over a month.
Even though the days do fluctuate a bit. So although this Katch-McArdle method maybe feels a bit simplistic, kind of back of the napkin, unscientific – it works. And it is based on good science. It works for cutting, it works for lean bulking, it works for maintaining. And while there is a place for fancier protocols like calorie cycling.
For example, which you can learn more about if you Google “Muscle For Life calorie cycling”, you’ll find an article I wrote on it, which I may record a podcast on as well. But so while there is a place for stuff like that, for most people, they can just keep it simple as far as calories in and calories out goes, and adjust based on how their body responds, and get the results that they want.
So if you want to learn more about using the Katch-McArdle method to estimate your TDEE, Google “Legion Athletics TDEE” and you’ll find an in-depth article that I wrote on it that also has a calculator that will do all the math for you and make it very easy. I figured that’s better than breaking it down here in the podcast. You might as well just go to that article and you can just use the calculator if you don’t even want to read the article. But if you want to learn a bit more about the theory behind the calculator than it is there in the article.
[00:27:46] So that’s really all I wanted to cover in this podcast. And remember that in the end, you do not need to be 100 percent accurate with your estimations of calorie expenditure. You just need to be accurate enough to be able to create meal plans that work. And what it all comes down to, of course, is how your body responds to what you eat.
If you are losing weight and you are losing fat as desired, you are eating fewer calories than you’re burning regardless of what the machines or the math might say. And similarly, if you are not losing weight, not losing fat, you are eating too much, regardless of what a calculator might say or what your calculations might say. And while that doesn’t necessarily mean the solution is to simply eat less, you do need to create a larger calorie deficit if you are going to lose weight.
[00:28:39] And if you are gaining weight, of course, that means that you are consistently eating more calories than you’re burning. And if over time you’re not gaining or losing weight. If you are more or less maintaining your weight, that means that you are more or less eating what you’re burning.
[00:28:56] So remember those guidelines because they take precedence over all of the mechanics that might go into trying to estimate your calorie expenditure. If your body is not responding in the way that you want in terms of body weight in particular, and to some degree, body composition, first and foremost is energy balance.
You need to look at your energy balance and review how many calories you’re burning, how many calories are you eating, and adjust things based on what is actually happening with your body. Because whether you use the Katch-McArdle method, or the MET method, or some other method, you are just producing a starting point.
You’re producing what is hopefully an accurate estimate of energy expenditure, but it may not be as accurate for you as it is for other people. So you do need to make sure that you are ultimately getting the results that you want. And even if it doesn’t quite square up with the calorie calculations that you made in the beginning or that you are making right now or the advice that you’re receiving from somebody else.
[00:30:03] You know, for example, I have run into many guys over the years who have weighed anywhere from 150 to 170 pounds and who had to eat upward of 4,000 to 4,500 calories per day just to gain a half a pound, maybe a pound a week. And these were guys who were relatively new to resistance training or to proper resistance training and who were not tremendously physically active.
These were not guys that worked in warehouses, lifting boxes all day. They had normal desk jobs, but for whatever reason, their metabolisms were quite a bit higher than average. And they probably also engaged in a lot more spontaneous types of activities that they weren’t aware of, which, of course, burn calories and just add up to more and more calorie expenditure.
[00:30:51] But my point is, if you were to take any of those guys as information and put them in to whether it’s the Katch-McArdle or the MET calculations, you would get much lower numbers for lean bulking. So if you just wanted to put them in a 10 percent calorie surplus, on average, you would get probably 28, 29, maybe 3,000 calories.
Yet when those guys did that, that’s where they started based on my advice in my articles or books or podcasts, whenever they got the advice. They found that they were not gaining weight. And so they knew that that just meant that they needed to eat more food. Because they were now doing what they needed you in the gym, they were training hard, their volume, their frequency, their intensity was where they should be for their circumstances, and so they knew they just had to eat more food.
And again, in a number of cases, they had to eat so much more food that they had a hard time believing it based on what they had calculated in terms of calorie expenditure. It didn’t make sense to them, like, “how is that possible? According to this calculation I’m burning like 2,600 calories a day. And I need to eat over 4,000 calories a day just to consistently gain weight? How is that possible?” And it is possible.
[00:32:11] So again, when calculating your calorie expenditure, don’t get too lost in the weeds. Don’t get too caught up in the details. Just come to an accurate estimate and then use it and see how your body responds and adjust accordingly.
What did you think of this episode? Have anything else to share? Let me know in the comments below!
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