0:00 – Introduction: The Risk of Losing Lean Muscle in Weight Loss

0:14 – Importance of Maintaining Lean Muscle Mass

0:30 – Role of Metabolically Active Tissue in Weight Loss

0:38 – Impact of Caloric Restriction on Metabolic Rate

1:17 – Fat Mass vs. Fat-Free Mass: Energy Usage Explained

2:04 – Total Daily Energy Expenditure Breakdown

2:37 – Metabolically Active Organs and Their Energy Consumption

3:40 – Importance of Maintaining Fat-Free Mass for Metabolism

4:45 – Muscle Mass and Aging: Impact on Mortality and Health

5:52 – Case Study: Muscle Mass Changes from Young to Old Age

7:13 – Consequences of Muscle and Bone Loss in Aging

8:11 – Risks of Severe Caloric Restriction

10:51 – Importance of Micronutrients in Caloric Restriction

12:09 – Protein Intake: Key to Preserving Lean Muscle Mass

12:52 – Role of Resistance Training in Preventing Muscle Loss

13:45 – Importance of Adequate Protein and Resistance Training

14:14 – Risks of Yo-Yo Dieting and Loss of Lean Muscle Mass

15:28 – Strategies for Tracking Progress and Adjusting Diet

16:52 – Triangulating Symptoms, Weight, and Lean Body Mass

17:00 – Conclusion & Call to Action: Preserve Muscle While Losing Fat

One of the most significant concerns of any weight loss program, including fasting, is the loss of metabolically active lean muscle tissue. Now, in this video, I’m going to show you strategies that you can put in place to lose the body fat without shredding your muscle mass. Before we talk about those strategies, what I want to do is I want to talk about why it’s actually important to maintain our lean muscle mass.

So to start, The first most important piece or the first most important thing to know about muscle mass is that it’s our major source of metabolically active tissue. So if we start to lose a large portion of our muscle mass, if we go on a calorically restricted or a fasting type of diet, what winds up happening is when we are done with that diet, we drop our metabolic rate.

We do not have all of that metabolically active tissue available, which means that when we’re done, we actually wind up being able to eat less on top of the metabolic downregulation. So we have a quote here and they say, the human body contains tissues and organs of varying metabolic activity. With the simplest division of total body mass into two compartments, fat mass, also known as stored fat found in adipose tissue, and fat free mass, which includes smooth and skeletal muscles, connective tissue, water, and bone.

Although adipose tissue is the main storage site for energy in the form of triglycerides, it has a low metabolic rate at 5 kilocalories per kilogram compared to the 20 kilocalories per kilogram for fat free mass. So basically The fat tissue that we have doesn’t really use much energy, whereas the fat free tissue that we have, the muscles, the bones, the organs, the skin, etc, has a much higher metabolic rate.

So we want to maintain that tissue. That’s what’s going to allow us to actually eat more food when we come off the diet, when we stop losing that fat tissue. So the next thing I want to show you here is they say, Given that fat free mass is a strong predictor of resting energy expenditure accounting for 60 to 80 percent of inter individual variance in resting energy expenditure.

So 60 to 80 percent of our resting energy expenditure of our metabolic rate is accounted for by our fat free mass. So we want to maintain as much fat free mass as possible without losing that if you’re trying to lose fat mass. And I have a graphic here for us. That shows this. So basically, we have our total daily energy expenditure.

That’s our TDEE. And it’s composed of a couple components. Resting metabolic rate, active energy expenditure, and the thermic effect of food. So what we see is our resting metabolic rate accounts for 60 to 75 percent of our total daily energy expenditure with fat free mass accounting for 60 to 70 percent of that resting metabolic rate.

So essentially, 60 to 70 percent of our largest source of our total daily energy expenditure is from our fat free mass. Now, they break it out further here, and what we see is that the brain, the liver, the kidneys, the heart, the skeletal muscle, they show adipose tissue, but residual mass, they’re giving us the different breakdowns here.

These are some of the most metabolically active components. So the brain using 240 calories per kilogram per day deliver 200 calories per kilogram per day. The kidneys 440. Kilocalories per kilogram per day. The heart 440 muscle, 13 kilocalories per kilogram per day. And the adipose tissue only 4. 5 kilocalories per kilogram per day.

The adipose tissue isn’t really using that much energy. It’s all of our organs, our muscles, et cetera. So brain, liver, kidneys, heart, skeletal muscle. Now, after that, what we see is our activity, energy expenditure. So physical activity, exercise, and then muscular efficiency or non exercise activity, thermogenesis.

So this is just kind of moving around throughout the day. Okay. This accounts for about 10 to 30%, and then the thermic effect of food, which is the actual energy it takes to process the food during digestion and metabolically throughout the body accounts for only 10 to 50%. So most of this is coming from a fat free mass.

This is why we do not want to lose our fat free mass. Now, the second reason That we do not want to lose our fat free mass is that as we age, we are already losing our muscle mass, which is the largest portion of our fat free mass and lower fat free mass is associated with more mortality. So the lower your fat free masses, the lower your muscle mass, the higher risk of mortality.

And so we have a quote here from a paper. The paper is titled live strong and prosper. The importance of skeletal muscle strength for health. And what they say here is, in contrast, human preclinical, clinical and large cohort perspective studies demonstrate that aging leads to anabolic impairments in skeletal muscle, which in turn leads to reductions in muscle mass and strength, factors directly associated with mortality rates in the elderly.

So basically, the less muscle mass you have and the weaker you are, the higher your risk of mortality. They say, as such, increasing muscle protein synthesis via exercise or protein based nutrition maintains a strong, healthy muscle mass, which in turn leads to improved health, independence, and functionality.

So we do not want to lose our muscle mass. We want to make sure that we have adequate amounts of muscle mass across the lifespan. The next thing they say is during aging, approximately 30 percent of an individual’s peak muscle mass is lost by the age of 80. And this loss is exacerbated by physical inactivity and poor nutrition.

So when you’re 25 is roughly the point where you have peak muscle mass. By the time you’re 80, 30 percent of that muscle mass is that can actually be decreased on average. Now, the thing is, is people say, well, my weight doesn’t change. Well, what’s being replaced is body fat. And so what we can see here, I have a nice graphic.

Is you have a young 24 year old man and you can see this is a cross section of different muscles of different people’s muscles and what you see is the young man you can see the bone here in the center and you see all the muscle mass in there and you see the fat mass around so there’s not much fat infiltration there and most this is muscle mass but then when we get to a 66 year old man we can see that he has a lot more fat mass present and the muscle mass he has has fat infiltration present in it.

And we see another 66 year old man, presumably a bit healthier. They stratified these by activity levels. So the 66 year old man over here with the fat infiltration was averaging about 3, 000 steps per day. Whereas the man over here, that didn’t have as much fat infiltration, you can see the muscle is much leaner and the fat is mostly around the outside, closer to that 24 year old man, basically, he was averaging 12, 445 steps.

The physical activity is protecting the muscle mass. And then we can see in the graphs over here, that muscle cross section area, from the time we are in our 20s, which is about our peak, as we get older, we see that muscle cross section area starts to decrease over time. So basically, as we get older, we’re losing it.

So we don’t want to put strategies in place. Like heavy caloric deficits that shred our lean muscle mass, especially as we get older, because what winds up happening is that we’re going to have a harder time putting that back on. And so, and it’s also associated with worse mortality, uh, risk and also worse metabolic and disease outcomes.

So the further thing they say here, and this explains what I was just talking about, musculoskeletal deterioration, old age has several health consequences, skeletal muscle and extracellular matrix of skeletal tendon bone are essential. for maintaining tissue structure and vital for muscular contraction and forced transmission.

Given the close link between muscle loss sarcopenia and bone loss ossopenia, factors that affect muscle anabolism are also likely to affect bone mass. With advancing age, sarcopenia and osteopenia present major clinical problems, such as impaired locomotory function, compromised balance, increased risk of osteoarthritis, and fallen fractures, all of which diminish quality of life in seniors.

So basically what we’re seeing is that as you lose muscle mass, you can also lose bone mass, which leads to a loss of the ability to move around and function appropriately for the activities of daily living. Also compromised balance. So basically the inability to maintain appropriate balance where you have an increased risk of falls.

And then because the bones are weak, increased risk of fracture. Now, while I was working in the ICU, I can’t tell you how many people I saw who came in with broken hips. And the broken hip, a lot of times, can be pretty serious for somebody who’s at advanced age because you go into the hospital, then you become sedentary in the hospital because most times you’re in the bed because the hip’s broken and hospital staff doesn’t want you out of the bed because you’re a risk for falls, and then maybe you get pneumonia or there’s infection in the hospital.

And it just goes from there and things can spiral downward. So that’s a big problem with like some of the caloric restriction stuff is you don’t want to lose that muscle mass and that bone mass because then you may be putting yourself at risk down the line for injuries like falls that can, you know, potentially be life ending for for people who are frail or elderly or aging and things like this.

The next thing is, given these two factors, given that we see that muscle mass, having higher muscle mass protects against aging, And then having adequate amounts of muscle mass maintains our metabolic rate. There’s five things that are key to maintain lean muscle mass if you’re on a fat loss setup or you’re trying to lose fat.

Now, the first thing is appropriately setting up the diet. We want to make sure that the diet is managed from a macronutrient and micronutrient perspective so that you don’t create serious issues with a caloric restricted diet. We have a quote here, the paper’s title, Impact of Calorie Restriction on Energy Metabolism in Humans.

And what they say is, the most important consideration for the study of caloric restriction is the requirement for adequate nutrition, including sufficient intake of macronutrients and micronutrients. This necessity is best demonstrated by the Minnesota Starvation Study, a landmark study of severe caloric restriction by Keys et al.

So this is the famous Ansel Keys Minnesota Starvation Experiment. In this study, 40 percent caloric restriction was induced by dietary restriction increased exercise. The young man lost 25 percent of body weight, of which 75 percent was fat mass and 30 percent fat free mass. The diet was designed to mimic conditions of warfare and therefore was deficient in many nutrients.

The malnourished, caloric restricted diet led to chronic weakness, reduced aerobic capacity and severe, painful lower limb edema. Furthermore, various abnormal psychological behaviors were observed, including severe emotional distress, confusion, apathy, depression, hysteria, hypochondriasis, suicidal thoughts and loss of sex drive.

In contrast, the largest and best controlled clinical studies of caloric restriction in non obese individuals prescribed caloric restriction of 25%, 12 18 percent caloric restriction was achieved, so the research is set for 25%, but people only maintained about 12 18 percent caloric restriction, and intentionally ensured adequate intake of micronutrients by provision of a vitamin, mineral, and calcium supplement to subjects.

With this moderate level of caloric restriction and nutritional adequacy, there was no increased frequency of adverse events compared to individuals continuing their usual diet. So essentially what you’re seeing here, a poorly set up caloric restricted diet with a really heavy caloric restriction leads to 30 percent drop in fat free mass.

So they lost 25 percent of their body weight. 30 percent of that was from their muscle tissue or from their, their lean tissues. So more than just muscle tissue, but other tissues as well. And 70 percent of that was fat mass. But because the diet wasn’t set up appropriately, the individuals in the study had a whole bunch of problems around their health and also around their different psychological states.

Whereas you have another study set up where you had a roughly 12 to 18 percent caloric restriction set up with adequate micronutrients and the people didn’t develop those same levels of severe problems. So with that said. Let’s dig into micronutrients. So the next thing here is you want to make sure if you’re on a calorically restricted diet to lose fat, that you have adequate amounts of vitamins and minerals, because if you’re not eating enough, you’re going to, it’s, you’re going to have a harder time to hit these targets.

So we have a paper here that says requirements for essential micronutrients during caloric restriction and fasting. And what they say is, it is essential to note that caloric restriction may lead to a proportional reduction in micronutrient intake unless corresponding supplementation is provided.

Historical human case reports on caloric restriction have consistently maintained adequate intakes or recommended dietary allowances for essential micronutrients, including vitamins and minerals. Similarly, longevity studies involving non human primates have upheld micronutrient consumption levels comparable to control groups or baseline measures.

Recent randomized controlled trials have also endorsed daily supplementation of multivitamins and minerals to meet micronutrient needs. So in a lot of the caloric restriction studies, both human and animal, they actually supply vitamins and minerals to make sure that the humans and the animals in the studies actually have enough of their micronutrients because they know when they go on these calorically restricted diets that they’re not getting enough of these components.

So If you’re going to do anything like this, you want to make sure that you have enough vitamins and minerals present to maintain your metabolic function altogether, as well as you make sure that the diet is set up appropriately. Now the next thing, and this is a huge one, is adequate protein intake is absolutely key.

And so we have a study here that say resistant training prevents muscle loss induced by caloric restriction in obese elderly individuals, a systematic review and meta analysis. What they say is preservation of lean body mass with caloric restriction could also be obtained by additional protein intake.

Longland and colleagues have shown that caloric resistance and resistant training with high protein consumption induces increase in lean body mass and promotes larger fat loss if compared to caloric resistance resistant training with low protein consumption. The only study has investigated the caloric restriction effects in combination with high protein intakes 30 percent protein compared to 50 percent protein found lower lean body mass loss So basically I have two groups one’s caloric restriction and resistance training with a high protein One’s caloric resistance and resistance training with a low protein and the group that had caloric restriction with resistance training and the high protein

So, that brings us to the next piece here, is that it would be ideal to actually set up a resistance training regimen. So, what they say here in the next quote, is they say, the main finding of the present meta analysis, Was that caloric restriction and resistant training prevents 93 percent of the lean body mass loss induced by caloric restriction, although it does not affect body mass and fat body mass reductions as compared to caloric restrictions without resistant training.

So essentially what we want to see is if you’re going to set up a diet. To lose body fat and you’re setting up a calorically restricted diet. You want to make sure that the caloric restriction you set up is not excessive. You want to make sure that you have adequate amounts of micronutrients. You want to make sure that your protein intake is dialed in effectively.

And ideally you would be resistance training such or stimulating the muscles. You’re not losing that muscle mass because as we talked about before, if you lose a bunch of lean tissue in the form of muscle mass, you lose that fat free mass. By the time you’re done with that diet, you’re going to have a dropped metabolic rate.

Your basal metabolic rate is going to drop because your lean mass accounts for at least 60 to 80 percent of your basal metabolic rate. And this is something that I see with a lot of clients who’ve gone on the, the diets rollercoaster. They go on a diet to lose weight. They’re not really looking at how they’re actually setting that up and they lose the weight, but they also lose a bunch of lean body mass.

And then by the time they lose that lean body mass, when they start to eat again, their metabolic rate is lower and then they gain body fat again. Okay. And so if you don’t set things up appropriately, you can actually dig yourself into the hole. And this is what I think many people experience is they dig themselves into that hole through the constant yo yo dieting.

And it basically is up and down and up and down until you’re all the way down. You keep moving down with your basal metabolic rate because you keep dropping lean muscle mass. And this is especially a problem For women that I worked with because by the time I start to work with them, they’ve already done multiple weight loss diets before.

And then they’re in a circumstance where their lean body mass, when I start to calculate it based on estimated body fat percentage from total body weight, it’s like, wow, the lean mass is pretty low. And it’s like, this is why you’re having trouble losing the weight and why you’re putting weight on so easily.

And so then what winds up happening is we have to start to increase that lean muscle mass again and do a variety of things. To rebalance the scales. And as we talked about, as you get older, it gets a little bit more difficult to put on that lean muscle mass. Now, the last thing here, that’s absolutely essential.

When you are doing anything like this is you need to track your progress. And so what you want to do is you want to triangulate what’s going on. So what you want to see is you want to see what are your symptoms on this diet? Is your sleep bad? Is your energy bad? Is your mood bad? Is your cycle off or hormones off all of these components?

That’s your body giving you indications. That maybe the deficit is too heavy, or maybe you’re, you’re starting to get hormonal problems from doing something like this. The next thing you want to do is you want to see what’s going on with your weight on a regular basis. So that you can see, are you going down?

Are you going up? Are you maintaining? Because basically you want to see, are you reaching that goal? The other thing is you probably, if you can, would want to track your lean body mass with something. It’s not perfect, but like a bioelectrical impotence scale. So it’ll give you an idea of where lean body mass is to some extent.

And you can watch the trend, even though it’s not the most precise way to measure things. There’s also things like DEXA scans that includes radiation, which is a story for an entirely different video. So that’s another thing. Another thing you want to keep in mind is your progress in the gym. Cause ideally you would be doing resistance training and seeing if your weights are going up and if you’re getting stronger, that’s an indication of, to some extent of what’s going on with your muscle mass.

So when you take your weights in the gym, your symptoms, your weight on the scale, and in a measurement of your lean body mass, you can try to triangulate and gauge what’s going on with your weight loss protocol overall. And you can see, am I losing lean body mass? Am I feeling pretty good? And then that’s how you can kind of gauge if the deficit that you have set up to lose the body fat is set up appropriately.

Now, with all of this said, if you’re looking to comfortably lose body fat without losing muscle mass, you can head over to mikefabe. com and check out my neurovi program where I can personally walk you step by step through this process. And if you like this video and want to learn more about weight loss, check out this recent podcast that Ethan and I did discussing weight loss via fasting, ozempic, and the low carb dieting.