Dr. Patrick: With respect to body composition, so, you know, we're talking about the benefits of resistance training on bone density, obviously, muscle mass, and people are now thinking about those things but, you know, back in the day, you know, body composition, and it still is important as well, but that was kind of one of the major things people would think about, like, why they should do resistance training. Can you talk, like, a little bit about body...like, how does resistance training, you know, affect body recomposition, can you gain muscle without gaining fat mass? Sort of things like that...

Dr. Schoenfeld: You know, great question. So, well, let's start from the basics that resistance training, certainly it improves lean mass, which is largely muscle mass. I do think it's important to understand, like, certain measures, underwater weighing, like, a lot of the measures that you'll see, DEXA, underwater weighing, BIA, bioelectrical impedance analysis. They are looking at not necessarily muscle mass, although there are ways to try to derive that, but when they talk about fat-free mass and lean mass, generally, depending on the measure, they're combinations of in the very least muscle and water. So, it's not necessarily just, if you're gaining water, that'll show up as fat-free mass, anything outside of fat mass would be fat-free mass. And that, I think, is somewhat important to understand there. But, with that said, resistance training certainly can impact fat-free-mass aspect and it can help with fat mass.

Now, I want to say, in general, and this goes for cardiovascular exercise too, exercise is not the best way to lose body fat. It can help, it's certainly I think a good adjunct to a fat-loss program, which I'll get to in a second, but you have to do a lot of exercise to meaningfully lose fat, whereas it's just much easier to do it through reducing the calories in nutrition, the energy intake. So, for instance, if you do an hour of cardiovascular exercise, and hard, you know, where you're running for the most part, I mean, you can burn 500-600 calories in that hour. You know, you have a bag of potato chips, that can pretty much offset everything you've done. Whereas, if you focus on reducing the energy intake through your food and using exercise as an adjunct, it can certainly help with weight loss. Not only in terms of increasing energy expenditure, to some extent...because, by the way, during an hour of exercise every day, for most people it becomes very laborious.

And that's just cardio. Like I said, you want to do resistance training as well. And resistance training...cardio actually is somewhat more effective, just purely from creating more energy expenditure, than resistance training is. But here's the catch, it is, in my humble opinion, fundamental to combine resistance training at the very least with an energy deficit through nutritional restriction to promote weight loss. And here's why, if you do not lift weights, even if you just do cardio, you will lose muscle as you're losing body fat. And depending upon how you're going about it, evidence shows 25% to 30% of the weight loss will come from muscle. So, you might lose, let's say, 70% fat, it can even be more if you're somewhat leaner, and 30% coming from lean mass if you don't do resistance training.

Now, you talked about recomp, resistance training not only will stave off the loss of fat-free mass often but you can actually recomp. Recomp means you can gain muscle while losing fat. There are two primary factors, and I'll leave out...so, there's three, the elephant in the room is anabolic-steroid use. So, if you're taking anabolic steroids, yeah, you can have serious recomp. But putting that aside, that's probably not your audience or most of the people listening here. The two primary factors are, number one, "How much weight do you have to lose?" So, the more weight you have to lose, the easier it is to recomp. Also, how long have you been training? So, someone who has a lot of years of experience of training, that's closer to their genetic ceiling, will have a more difficult time recomping.

Now, by the way, so, if you have a lot of body fat to lose and you're just starting out, you can do serious recomp, I see this all the time. Not only anecdotally have I seen this in clients but we have controlled experiments run through our lab where I see this all the time, and individual subjects that we have. You cannot, however, maximize muscle mass while you are losing fat, so, this is important. If your goal is to go into, let's say, a mass-gaining cycle where you want to...let's say, bodybuilders do this or strength athletes, and your goal is to maximize muscle development, you're at the very minimum going to need to be at maintenance, and generally you're going to need to be in a small surplus where you're going to gain a little bit, at least some amount of fat.

Dr. Patrick: Okay. Boy, this is fantastic information, it's sinking all in. So, if you are in a caloric deficit, and this kind of brings us into the dietary-protein-requirements world a little bit, if you are in a caloric deficit but you are...and we should probably talk about what the protein requirements are, but, let's say, you are getting sufficient protein intake, daily protein intake, to prevent your body from pulling protein out of your muscle, basically, can you not lose the lean mass or muscle mass? Let's say you're not doing resistance training but you are just getting the protein in, say, you're doing aerobic but you're still in the caloric deficit but you're getting protein...

Dr. Schoenfeld: And not lifting weights?

Dr. Patrick: You're not lifting weights.

Dr. Schoenfeld: So, the answer is it will help to preserve some lean mass but you'll still, no matter what, if you are not lifting weights, I mean, this has been shown again over and over in research, you will lose...well, I want to at least...I always hate to talk in absolutes because if you're very obese where you just have, let's say, you're 100 pounds overweight, you can lose fat without losing muscle because you just have so much fat to lose that the body is going to pull from the fat storage, but I'm talking when you're starting to get down into, you know, people who're just, quote unquote, "overweight," you're going to lose muscle if you do not resistance train. Now, I want to point out though, even if you're lifting weights, if you are getting insufficient protein, you're going to leach some muscle. So, you need to still take in sufficient protein. And there's actually evidence that you need more protein than what has been shown for people at maintenance or above to maintain muscle or even to gain it, slightly, when you're in a caloric deficit. So, that actually increases protein needs, to some extent.