 Hey everyone, Dr. O here. In this lesson I'm going to talk about a super important topic, how exercise preserves muscle when you're on a diet. I'm primarily going to talk about it in the context of different fasting protocols, like time-restricted feeding and alternate day fasting, but this would be important for anyone that's in any sort of calorie deficit, whether you're doing it with fasting or some other dieting strategy. So you see here a picture of people sitting around a boardroom. This is how I actually envision the human body deciding how to divvy up resources. So imagine that every organ system is sitting at the table because they have to make budget cuts. This is a serious meeting. There's less income coming in. That's the food, right? There's less income or money coming in, so cuts are going to have to be made. Maybe you've worked in a business where these types of meetings have gone on. So there's less food coming in. Your body has to determine how it's going to divvy up the limited resources that it has. So here's how this meeting would basically go. Your brain's going to say, I don't have anything to spare, right? Your brain takes whatever it needs all the time, and then the other organ systems are going to make an argument as for why they should get a piece of the pie, right? So if your brain's going to say, hey, I have nothing to spare, you have to make sure that your muscles and your bones say the same thing, right? Your muscles and bones need to be saying, look, we're being used every day. We're not a fuel source, right? This person is exercising. They're lifting heavy things. We can't afford to give up bone. We can't afford to give up muscle. If you don't do that, if you don't send that signal to your body, then your muscles are just a fuel source. Your muscles can be, you know, the proteins in your muscles can be broken down and turned into glucose through a process called gluconeogenesis or the creation of new glucose. So your muscles just become another fuel source if you are not using them, right? That's what makes them fair game is fuel. So strength training preserves your muscle so that you can hold on to that lean tissue. That's so keep that in mind as we go through everything else here. Send a signal to your body that your muscles are off limits. They can't be used for fuel. So let's look at what the science has to say. We covered this study actually in the series on sleep and weight loss roadblocks that I talked about. Insufficient sleep undermines dietary efforts to reduce adiposity. So why are we talking about that here? I want to remind you that the people that were good sleepers, the people that were sleeping eight and a half hours a night, yes, they lost, you know, their 6.6 pounds give or take just like the group that was sleep deprived. But they still lost half of the weight they lost was lean mass. They lost around 3.1, 3.2 pounds of fat, and then about 3.3 pounds of lean mass. And I said, and I still believe it here, that if they were resistance training, those numbers would have been even better. So yes, if you're sleeping well, you'll lose more fat and less lean tissue. But if you're sleeping well and add resistance training, you're going to lose even more. So the rest of the studies I'm going to show you here are talking about people that are resistance training. But just compare that to this. This group was sleeping well, but they weren't resistance trained. Half the weight they lost was lean tissue. So let's look at what happens when we add in exercise and resistance training specifically, strength training, lifting weights. Alternate day fasting and endurance exercise combine to reduce body weight and favorably alter plasma lipids in obese humans. So this study found there were three different groups. There was a group that was doing alternate day fasting, a group that was doing endurance exercise, and a group that was doing both. So the combination group, the group that was doing both fasting and exercise lost 13.2 pounds. The group that was only fasting lost 6.6 pounds. And the group that was only exercising lost 2.2 pounds. So you can see here that adding fasting and exercise together will accelerate your fat loss and weight loss. And if you're here because you want to lose fat, you want to lose weight, that should be all the reason that you need. But even more exciting is the lean mass was retained best in the combination group. So they lost the most weight, but they retained their lean mass. So notice the group that wasn't exercising still lost half their weight as fat. This group retained their lean mass and lost almost all of their weight as fat. All right. So the conclusions from this study, I'm just going to read it to you. These findings suggest that the combination of alternate day fasting and exercise produces superior changes in body weight, body composition, and lipid indicators of heart disease risk when compared to individual treatments. Next study, time restricted feeding in young men performing resistance training, a randomized controlled trial. Now, in this study, they were actually only using a four hour eating window or feeding window, which I wouldn't recommend for anyone that's really concerned about building muscle or not losing muscle. And then their workouts where they alternated upper and lower body workouts. But in this study, the time restricted feeding led to a 650 calorie per day deficit, but it did not affect body composition during the study. So overall, they reduced their energy intake, but they did not lose lean mass. And they actually saw muscular improvements by resistance training while they were fasting. So you look at these studies, if these groups were not resistance training, they would have been losing lean tissue and fat by adding resistance training, they were losing almost all fat, sorry, not lean tissue, they were losing almost all fat. Next study, effects of eight weeks of time restricted feeding a 16 eight protocol on basal metabolic rate or basal metabolism, maximal strength, body composition, inflammation and cardiovascular risk factors in resistance trained males. Let me read the conclusion. Our results suggest that an intermittent fasting program in which all calories are consumed in an eight hour window each day, in conjunction with resistance training, could improve some health related biomarkers, decrease fat mass and maintain muscle mass in resistance trained males. Another study saying the same thing, exercise maintains the lean mass. You're sending the signal to your body that muscles aren't fuel muscles are needed. Another one, time restricted feeding plus resistance training in active females, a randomized trial. So in this study, they looked at different time restricted feeding protocols. And they found that it did not impair muscle gain or performance. They were actually trying to get stronger and build muscle. And as long as they, they kept their eating window at eight hours, then they actually didn't see any problems with it. So in this case, they were able to lose fat, build muscle and get stronger. As long as they were on a time restricted feeding protocol where they were where they weren't going, they had an eight hour we eating window, which means they weren't fasting for longer than 16 hours. I just want to let you know that a performance and muscle gain in your primary goal actually don't recommend fasting. I definitely don't recommend any fasting protocol longer than eight hours, or where you have a feeding window that's shorter than eight hours. But multiple studies have shown that a 16 eight fasting protocol perfectly fine, even if your focus is muscle gain and performance. But I recommend creating a more anabolic environment if that's your goal. Like personally, when I take breaks from fasting, when I'm in a muscle gain phase, when I'm trying to gain muscle, I will actually eat more often and I will fast less often. So I think fasting is a phenomenal tool for decreasing your calorie consumption and losing body fat. But if your primary goal switches from fat loss to muscle gain, then you're going to want to stop alternate day fasting. You're going to want to stop doing the longer extended fasts and focus on a 16 eight eating window or maybe even like a 12 12 something like that. Alright, so what are the key takeaways here? Super, super important. Exercise increases weight loss on a fasting program and exercise decreases lean mass loss during a diet. So what do we do with this information? Well, the biggest question you're going to have, you have to determine the best way that you can add exercise to your weight loss program, right? For some people, that's hiring a personal trainer and working out 10 hours a week. For other people, it's going to be the minimum effective dose, right? The key with minimum effective dose though is the word effective. You have to determine how little exercise could you get away with to maintain these benefits? You know, I'm working with several people right now and we're kind of figuring that out. They don't want exercise to be a huge part of their program. So we're trying to figure out how little can they do to preserve mass or lean mass. So determine how much exercise is enough. So how much, how much exercise you need is going to change as you get more physically fit. But the key is you need enough to challenge you and it's called progressive overload for a reason. As you get stronger and you get more fit, that overload is going to have to continue to increase. But just think about that. You need enough to challenge you. If you're first getting started and you have a lot of weight to lose, then taking walks, riding a stationary bike, these kind of things will be enough to challenge your muscles. I always recommend though doing upper and lower body things. So maybe you're doing push-ups against the wall or assisted push-ups on your knees, swimming, whatever it is, use as many of your muscles as possible. And I also recommend doing that on the days that you're eating the most because you want to fuel your physical performance. So make sure you're doing enough to challenge you, right? When I first started 30-minute walks were actually really challenging for me. Now I might train for two hours lifting very, very heavy weights, right? So things have changed a lot. But just so you know, you don't need a huge exercise program to make tons of progress. I lost my first 100 pounds with nothing but walks and some resistance bands and some videos I saw on YouTube. So just keep that in mind. But you have to continue to challenge yourself and continue to increase. So maybe if you start with body weight squats, then get some five-pound dumbbells and maybe then some 10-pound dumbbells. Or start with some resistance bands and then move on to heavier weights. Increase the distance that you walk or swim or do these kind of things. But remind yourself if it doesn't challenge you, it doesn't change you. So if you're not pushing your body, then it's going to start to get easy for your body. And if it starts getting easy, then your body might start to see some of that lean tissue as an available fuel source while you're on a diet. So get some exercise, figure out how much you need and get after it. I hope this helps. Have a wonderful day. Be blessed.