Transcription
What is the best way to lose fat? A new meta-analysis has investigated this question by looking at 92 different studies and ranking how well the different types of interventions performed.
Without further ado, here is the ranking for body fat percentage loss, which is, I think, most important. The ranking was very similar for total body fat loss, measured in kilograms, and for all outcomes combined. In this image, you can see that energy restriction, by far, is key. You need to lower energy intake. Makes perfect sense in terms of thermodynamics to lose fat.
You don't technically have to be in energy deficit to lose fat, but it is much easier and much more guaranteed because the body has to get rid of some energy. It has to burn some of your tissues to get rid of that. And if you are lucky, it will burn adipose tissue, namely fat mass, rather than your heart or muscle tissue. Typically, it won't do that.
So, at the very top of the hierarchy, we have energy restriction plus a high protein diet plus exercise, which resulted in the greatest reduction in body fat percentage. That seems to be basically the holy trinity of fat loss. You need to perform some type of exercise, have a high protein diet, and restrict your energy intake.
Now, as for the type of exercise, interestingly, we actually see—and I think this is going to be in contrast to what many people think intuitively—although many of my long-term subscribers should not see this as a big surprise. Resistance training, meaning weight training or strength training, was more effective than aerobic training. You can see this in the ranking, both with energy restriction and without energy restriction.
Resistance training is higher in the hierarchy than aerobic training. It's not a huge difference, but it's consistent in all measurements and with and without energy restriction. This finding is actually consistent with an earlier 2015 meta-analysis of the literature, which also looked at a broader age range of individuals. Although it didn't have as many studies as the current one, they found that resistance training was more effective than aerobic training to lose fat, again, and also more effective than a combination of aerobic and strength training.
In the hierarchy of this current meta-analysis, mixed training is higher, at least without energy restriction, than resistance training. That's probably because they didn't control for volume. The earlier meta-analysis also looked at the duration of the interventions. So, mixed interventions in general, meaning they have aerobic training and strength training, will have a higher total volume of exercise.
If you go to the gym three times and do cardio three times, of course, that's probably going to be more effective than just going to the gym three times or just doing cardio three times a week. In the other meta-analysis, they controlled for duration as well. There’s also a nice study around the same time that found that strength training was also the most effective.
Now, this might be a very novel finding to many people, like strength training being better than endurance training or cardio for fat loss, and there are multiple reasons why this is the case.
First reason, as you can see in this image here, the acute energy expenditure of different types of exercise is not that wildly different. In general, I think it's fair to say that aerobic exercise is more practical to induce a high energy expenditure for a long period of time. But when you get to very high levels of energy expenditure, you typically cannot sustain that intensity for like an hour or 90 minutes, which you can do with strength training.
Most strength training workouts last about an hour, maybe 90 minutes for a serious workout. It's difficult to keep up that work pace with something like interval training. You're just not going to be able to do it. If you do lower intensity cardio training, then the difference in energy expenditure is going to be pretty similar.
Here you can see, for example, treadmill running, bicycling, and weight training are actually all quite similar. Now, there are definitely studies where this is not the case, and if you're very endurance trained, you can have significantly higher work output. So, you can have higher energy expenditure with cardio; it's more convenient.
But what the study also found, you can see that HRS, in terms of calories per minute, outperformed all the other groups. HRS means circuit training; I have no idea why they chose that abbreviation, but it basically means you are doing one exercise, and immediately after, you go to another exercise, then another exercise, etc. So, you don't rest much.
This goes to show that the type of exercise is really the key and how you perform it with how much effort. If you want to do your workouts primarily to burn energy, you can also do that in the gym by doing very high repetitions, super short rest interval circuit-type training. If you want to do cardio, that can also be very effective.
But it really depends on the type of exercise that you're doing much more than whether you're on a treadmill, on a bicycle, or using weights or whatever. So, all in all, there's not a big difference between strength training and aerobic training in energy expenditure.
Aerobic training is generally, on average in the literature, probably going to win out in terms of the acute energy expenditure, but that is offset by a factor of two higher excess post-exercise oxygen consumption (EPOC), as you can see in the graph here. After exercise, there is still an increase in oxygen consumption, and also in between your sets when you're doing strength training.
That's because you're basically catching up on oxygen debt. Your metabolism is still increased, in particular for strength training. There's also an increase in muscle growth in the next days, and that's going to also require energy expenditure. There's also tissue remodeling and repair of the body, and it's going to increase your energy expenditure for a couple of days even afterward.
Now, typically, EPOC is less than 100 calories in total, so it's not anything to write home about. But the acute energy expenditure of different workouts is actually also not as high as many people think. With cardio, it's usually between 200 and 600 calories, and with strength training, it's usually between 300 and 500 calories.
I did an earlier short on this, actually, where you can see some of the numbers on this. So, 100 calories can actually make a big difference in these values. Now, muscle growth is not just beneficial to get bigger muscles; it's also good for fat loss because it improves your P ratio, your protein ratio, or nutrient partitioning.
It means that if you're losing fat, and this new analysis also found that if you're losing fat with energy restriction without exercise, you lose some muscle mass. Now, any muscle loss is going to be less fat loss because your body loses or burns these tissues to fuel the energy deficit.
So, there's 500 calories that the body has to burn, and it's not consuming them from your diet. It needs to get 500 calories, so it needs to burn some of your tissues to get those 500 calories. Well, if it's burning one type of tissue, it's not burning the other. So, if you're losing muscle, that's energy restriction or energy deficit that your body's fueling with the muscle rather than via the fat.
So, it's a zero-sum game in economic terms. You're losing one or the other. You won't lose both because the body only has to get that energy once. So, muscle loss is actually also a problem for fat loss. Even better, if you're gaining muscle, that requires energy production and stores energy in the body.
So, the total amount of fat that the body has to burn for that is going to be even greater. The more muscle you retain or better build, the more fat directly as a result of that you will lose as a result of energy restriction.
Another big benefit of muscle mass increases is that it increases your energy expenditure over the long run. So, cardio is like an acute investment that you do right now. You do exercise, get some energy expenditure, and you lose a little bit of fat, and you have to keep that up because if you stop doing it, you don't get any return on investment anymore.
Whereas strength training is more like putting your time into the stock market. You'll get acute energy expenditure, so it's like you immediately get dividends, and you also get long-term returns on investment.
Basically, the point is that you don't just get acute energy expenditure, but you're also elevating your resting energy expenditure and your general total daily energy expenditure by increasing your muscle mass. Typically, those increases are not massive. We see 5% increases quite readily when people take up strength training.
When you get to differences between, like, bodybuilders versus sedentary individuals, we see differences in even resting energy expenditure of like 20%, which is very substantial. That basically means that if you don't change your diet at all, but you gain a whole lot of muscle, you're going to be in a 20% deficit. So, you're very much going to be shredded if you don't change your energy intake.
So, in the long run, that certainly plays a big role. It's also worth noting that while some studies find that the contribution of muscle mass to your resting energy expenditure is rather small, that is because they’re measuring sedentary energy expenditure.
Another factor that people should consider is that your total daily energy expenditure is going to be increased more because you're also basically just lumping around additional body mass. The more muscle you have, that's extra mass, extra tissue that you're carrying around, and especially when it's contracting and it's active, it's going to be increasing your energy expenditure.
But even if you're not using it at all, you have to carry it around all day, and that also burns some extra calories. So, getting jacked is actually like a long-term investment into your total daily energy expenditure, which makes it easier to get into an energy deficit.
Now, I think for most of our long-term subscribers, all of this so far is relatively straightforward. But there are two things that I think are a little bit more contentious and novel.
Namely, resistance training seems to be better than cardio at suppressing your appetite. There's some research that finds this for appetite-related hormone reductions or increases, depending on which hormone you look at, and also reductions in ad libitum energy intake.
So, a workout in general does not increase your appetite or change your appetite. This is another topic in itself, but most of the literature does not find effects of exercising on total energy intake, meaning that energy expenditure from exercise creates a free deficit because the body doesn't intuitively compensate for this.
Unlike with dieting, which creates an energy deficit, but then you also get hungrier. So, it's more difficult, and that's why exercise is so beneficial for fat loss when you combine it with energy restriction. Again, energy restriction is the number one thing that you have to do. A high protein diet also really helps with nutrient partitioning and similar benefits as strength training.
Now, research on this is not super clear, but there is some research, like I said, that suggests that strength training may be more efficacious to reduce your appetite than cardio.
Next mechanism—and this is one of the more interesting ones that current research is still investigating exactly how it works—is constrained energy expenditure. Your energy expenditure is not additive, so it's not like the more work you do, the higher your total energy expenditure. That used to be the model for a long time, and it's logical, right? The more physically active you are, the greater your energy expenditure.
This is not true. We now have solid research from various different fields showing that energy expenditure is constrained, meaning there are diminishing returns, as you can see in this graph here, to total physical activity level. At some point, getting additional physical activity, like an additional cardio workout or something, does not linearly increase your energy expenditure anymore.
There seems to be a compensation later on in your SPA or NEAT—spontaneous physical activity or non-exercise activity thermogenesis. This essentially makes you more tired and also more efficient with energy expenditure.
So, when you get home after a long cardio session, you can kind of feel this because you're more tired; you're going to be less active, and it's also in large part going to be subconscious. The energy efficiency in general is going to be improving in the body, and maybe you're not—when you're giving a presentation like I am now—you’re not going to be moving your hands all the time. You're going to be more... something like this.
Many of these things are more subconscious and not very deliberate, but they can actually make a big difference in total energy expenditure. I think the latest meta-analysis found that about 23% of energy expenditure was not translating into actual net energy expenditure.
So, it's like 23% less effect than you would get if you burn 100 additional calories. On average, you're only getting about 80 extra on your total daily energy expenditure because the other 20 are going to be offset, and other values vary a lot, even up to 50% or 80% in some cases.
That's particularly when you get to very high levels of energy expenditure, which might explain in the current meta-analysis why the combination of cardio and strength training doesn't actually do that much better than both. It's not as good as the sum of just aerobic plus strength training, and that's probably because you run into constrained energy expenditure.
There is some research that directly shows that adding another cardio session to the week when you're already doing a few does not actually increase total daily energy expenditure anymore. It seems to be completely offset in some cases, which might also explain why some bodybuilders feel like in contest prep at the end, you have to do insane amounts of cardio, or the amount of cardio you do doesn't even seem to matter.
It's not going to get you any more fat loss. You really have to reduce energy intake at that point. I myself have a very adaptive metabolism. I have very big adaptive thermogenesis, which is probably a very similar mechanism to what I just described of constrained energy expenditure.
It means that my metabolism adapts greatly to both decreases in energy intake and also to increases in physical activity. It doesn't have as much effect as you would think based on the acute energy expenditure/reduction in intake. So, that's a more complicated one.
But overall, it's clear that there are many mechanisms by which strength training can improve your long-term imbalance between your energy intake and your energy expenditure, which is the key to losing fat.
So, long story short, here are the three fundamentals that you need to do to lose fat:
1. You need to restrict energy intake. You can do this by either tracking your energy intake or with an ad libitum diet where you modify your food choices. By doing this, you will naturally end up with a low energy intake because you consume more satiating foods. You have a certain amount of appetite units, and you fill those up with less energy-dense foods. Therefore, your total energy expenditure is going to end up lower compared to when you were eating, say, McDonald's or junk foods, where it's not very filling and it is a lot of calories. So, you end up intuitively with very high energy intakes.
2. You need a high protein diet. I wrote an article on this on my website where you can look up in detail how much protein you should consume for maximum gains. But the long story short is that the latest meta-analysis, to which I was a co-author, found that the break-off point is about 1.6 grams per kilogram per day, which is, I believe, 0.72 grams per pound per day. I recommend 1.8 grams per kilogram per day, which is 0.82 grams per pound of total body weight, total protein intake per day. After that point, we don't see any further increases in muscle growth or strength development. You can have higher protein intakes, but there's really no point anymore.
3. Cardio is beneficial only if you're already maxing out your strength training. Before that point, cardio is still beneficial, but strength training is more optimal. You're going to get more return on investment per minute of exercise with strength training than with cardio.
I think this is probably the most interesting finding of the current meta-analysis. Again, it confirms that strength training is actually not just better for muscle growth, but also better for fat loss in the long run because of the aforementioned mechanisms.
All right. I hope that helps you get to your desired body fat percentage. If you want more of this type of content, I'd be honored if you like and subscribe.