Exercise and leanness

Below is an excerpt from Fit Body, Happy Joints: Episode 107 “Exercise and leanness”. 

In this post, I want to talk about exercise’s role on leanness or fat loss. 

I get a lot of questions about weight loss:

“Should I add more cardio?” 

“Is Evlo enough for weight loss?”

“How can I lose belly fat?”

Short answer: it’s diet, not exercise. But I’ll explain all of that in this post with the research. I’ll also explain how exercise can contribute to this weight loss equation- but not in the way you think.

My hope is to avoid contributing to the diet culture’s view on exercise as punishment and as a way to “shrink” your body. My goal is to provide information that will help give your brain “evidence” to exercise for yourself instead of against yourself. 

I want you to finish this post feeling educated, inspired, and more clear about the benefits of exercise. My hope is that it also helps you carve a path towards your goals, whatever they may be. 

In this post, I’ll present the research on exercise and fat loss and exercise’s effect on metabolism.

At the end, I’ll summarize everything and give you a practical plan for yourself going forward. 

Important qualifier

Before we get into this post, it’s important to address that being as lean as possible is not always healthy or recommended. 

I need to acknowledge that there may be many of you reading who do not need to focus on leanness at all. 

Low Energy Availability

There is a state called Low Energy Availability (LEA) which affects those who are very active and not eating enough. The risks of LEA can be serious: hormonal issues, suppression of reproductive systems (losing your period, infertility, etc.), mental disorders, and more. 

Sometimes LEA can happen unintentionally if you’re very active and just not educated about eating ENOUGH. 

There is no judgment here at all, but please consider seeking the help of a mental health professional and/or Registered Dietitian if you’re experiencing any of these symptoms related to LEA:

• Irregular or missing menstrual cycles
• Fatigue
• Mood problems, including irritability and depression
• Frequent illness
• Frequent injuries, especially stress reactions and fractures
• Decreased libido
• Increase in GI issues
• Poor or decreased training adaptations

Not to go off on a tangent for too long, but I cannot emphasize enough the importance of getting ahead of this if you may be experiencing. Because I can tell you that I have been in a place where I was likely experiencing LEA myself. I had all of these symptoms and more. 

My personal history

Many of you know my history of overexercising in my early 20s and experiencing all kinds of symptoms like fatigue, chronic pain, mental health issues, and sleep issues. 

I’ll never forget this feedback I got at a clinical rotation when I was in the height of my overexercise/under-eating stage. 

In the last year of PT school, you do clinical rotations where you work under another PT and they periodically give you feedback. 

During my feedback session, one of my clinical instructors called me “spacey,” like “I wasn’t there.”  At the time I was so upset about this feedback. I remember being exhausted, but trying my hardest to focus and be attentive. I thought “I truly don’t have anything left to give. I’m doing everything I can to be present and aware and it’s still not enough”. 

At the time, I thought there was just something wrong with me. I thought it was my ADD and that I needed to get back on ADD medication. But looking back, it was because I was overextending myself physically, not eating enough, and, therefore, never getting quality sleep and recovering. It was just this vicious cycle of trying to stay above water. 

Overcoming LEA

And I share this because I want to be a voice that it doesn’t need to be this way, and I truly did not know that you weren’t supposed to do that. I was operating in the “exercise is good, so more must be better”. And “eat less, move more”. I thought those symptoms were just the consequences of a “healthy” lifestyle. No one ever told me that it was because I was doing too much. 

Now that I no longer have severe mental fog (I haven’t taken ADD meds in over 3 years because I haven’t needed to) and I see better results from my training and I’m actually able to gain muscle and sleep through the night and have better relationships and I’m not starving all the time and I’m not hurting all the time, I will never ever go back to exercising more and more and eating as little as possible.

And I want to do all I can to call attention to this because I’m sure I’m not the only one who thought that these symptoms were a “normal” part of being fit. I’m here to educate and encourage that there’s another way.

If you think you may be where I was, this is your permission to exit out of this post and potentially reach out to someone to help you. I wish someone would have told me that it’s better on the other side, so I hope I can be that person for those of you who may be struggling right now.

How exercise affects leanness

If you’re still here it’s because you have identified that you would like to get leaner and that it wouldn’t be a health risk for you to embark on that goal. 

Let’s dig in. 

Here’s the bottom line up front: based on all the research, exercise is just not that effective for getting leaner. I will cite systematic reviews, meta-analysis, and other studies throughout this post to give you the clear evidence to support this claim. 

Exercise may have some effects on leanness and fat loss, but it may be for different reasons than you think.

What research says about leanness and exercise

A systematic review, which is one of the more quality forms of research since it reviews other studies and pools together a bunch of information, pulled data from 80 studies that looked at exercise alone for weight loss. 

These studies were included if they followed the participants for over a year. The conclusion from this review was this:

Exercise without dietary restriction does not produce significant weight loss. 

For decades we have been taught that exercise is part of the equation for fat loss. But the truth is, it really isn’t as important for fat loss as we have been led to believe. Study after study after study show that exercise alone provides modest fat loss (like 3lbs), if any. 

But why do so many people still believe that exercise is a tool for fat loss, specifically cardio?

A combination of history and advertising. 

Resistance training is relatively new as an exercise modality, as it really only gained popularity in the 70s, and even then, it was mostly for men. Until then, and still now, many women lean on cardio for exercise because of the lack of education around resistance training and its benefits. 

Quality research studies are still emerging on the benefits and effects, but the general public is behind because media still portrays that a sweaty, calorie-burning fitness class is what will drive results (aka fat loss). Even many of the leaders in fitness are still holding on to the old-school mentality that the calorie burn is what will move the needle. 

So it makes sense that our thought process around exercise for fat loss is to do more cardio. 

The truth is, weight loss comes down to a calorie deficit. Which means calories in have to be fewer than calories out. I interviewed a registered dietitian about starvation mode and if there are exceptions to this. But for the most part, that is the law of thermodynamics that will dictate weight loss.

So should you focus on burning more in your workouts?

It’s confusing because exercise burns calories, so it makes sense that if we exercise, we will accelerate weight loss. 

The problem is that it is very difficult to actually account for all the calories you’re burning, and most fitness trackers will overestimate calorie burn. 

Inaccuracy of fitness trackers

One study evaluated several popular fitness trackers on their ability to reliably calculate energy expenditure or calorie burn. The study concluded that none of the fitness trackers evaluated provide reliable information on energy expenditure or calorie burn. 

Because many people use watches as a tool to help them lose weight, they end up frustrated when they are exercising a ton, potentially “eating clean,” but still not seeing results. 

There are MANY reasons for the lack of fat loss results, but one is because focusing on exercise as your weight loss tool can contribute to compensatory mechanisms for eating. 

For example, let’s say you’re trying to eat around 2,000 cal to be in a deficit for weight loss (just using that round number). 

So you exercise and your tracker says you burn 400 calories. So now you can eat less than 2,400 calories and still be in a deficit. But our bodies often compensate for the calories we are burning in a workout by unintentionally making you more stationary, or borrowing from other calorie-expending processes. This is called the constrained total energy expenditure model, which I’ll get into in a moment. 

So your watch tells you that you burned 400, but maybe you only burned 200. So you eat 2,400 and are still in a surplus of 200 calories for the day. 

In this free workshop, I teach you how to find your TDEE which is the estimated number of calories you burn in a day. Then I talk about how to stay either right at that or slightly below for fat loss and body recomposition. I don’t recommend tracking exercise calories and adding that to your daily deficit, since it’s going to be so unreliable. I walk you through this whole process in the workshop. 

Constrained Total Energy Expenditure Model

There is an interesting theory which I’ve talked about many times on this podcast and in posts. It’s called the Constrained Total Energy Expenditure Model. 

Historically, we believed you could just exercise more and dig yourself into a deeper calorie deficit.The conventional wisdom was that the more you burned, the quicker the weight loss. 

But this seems to be flawed. Because your bodies don’t just burn and burn and burn. We tend to compensate after lots of exercise by borrowing calories from other processes to keep you within a narrow window of calorie burn. 

You may unintentionally decrease how much you move around and mental processing (which takes up a TON of energy expenditure), GI functions, and/or cell turn over may slow may slow.

This could be why over-exercise can contribute to LEA and lead to problems all over your body. Your body doesn’t have enough energy to use for important metabolic processes like mental health, GI health, cell turnover, recovery from workouts, and more. 

Hence why overexercise can make you feel tired/mentally foggy, look older, and make your body hurt.

Endless exercise is not the answer. We want to do enough to stimulate good things, but not so much that it backfires. Because it’s not actually improving your deficit anyway.  

We debunked conventional wisdom that exercise burns a lot of calories and, therefore, accelerates weight loss. But does exercise burn fat? 

How CAN exercise affect leanness?

Although exercise alone doesn’t result in significant weight loss just from a calorie-burning standpoint, it can indirectly influence fat loss via glycemic control, metabolic sensitivity, and insulin sensitivity. It can also improve mental health which may help improve eating behaviors, sleep, and overall activity. 

It’s actually less about the amount of energy you’re expending in the workout itself, and more about how exercise affects metabolic processes. 

Let’s get into this.

Using fat and calories as a fuel source

The act of exercising will use different fuel sources to power your movements depending on the intensity. 

Lower intensities, like steady-state cardio, use fat as their fuel source whereas higher intensities and muscle-strenuous activities, like lifting close to failure, will use glycogen from muscle and liver. 

Although cardio uses fat as a fuel source, the amount of fat burned is likely fairly negligent and may not result in much overall fat loss. 

Interestingly, although strength training close to failure and HIIT may not burn as much fat in the moment as lower intensity exercise like cardio, it may overall be more beneficial for fat burning because of the effects after exercise and its effects on your metabolism.

In fact, high intensity where you are using your muscles at a high threshold (i.e. strength training and HIIT) decrease abdominal fat more than aerobic activity even if calorie expenditure is the same

Why is that?

As exercise intensity increases, your body uses stored glycogen in muscles as fuel, not fatty acids. 

Let’s say you’re finishing your set of chest presses and the last few reps you have slowed down, you’re struggling, and you’re getting close to that failure point which we cue for in classes all the time.

Your body will begin to use stored glycogen in your muscles to power those last few reps, which will empty the stores of glycogen. 

Because you have emptied these sites, a few things happen:

1. Your body prefers to keep these sites “topped off” because they are the emergency stores.

So when you eat food, the first place your food will be stored (if there is room) is in the glycogen sites in muscle and liver. When you exercise and use your muscles hard (i.e. HIIT or strength training close to failure) you empty these sites. This means your food goes there first instead of to fat stores. 

2. You also have to work to replenish these stores after your workout, which requires fat as fuel to complete these processes. 

This can train your body to quickly shift from carb burning to fat burning, and improve what’s called metabolic flexibility. Increasing metabolic flexibility ultimately improves your ability to use fat as fuel.  

But if you are mainly focusing on cardio and never emptying these stores, you may be burning a bit of fat during the cardio itself (but likely not a significant amount) and you won’t see a change unless you’re in a calorie deficit. 

Whereas if you’re resistance training close to failure, sprinkling in some HIIT, sprinkling in some lower intensity cardio, and in a calorie deficit, you’re going to be hitting it from all angles and will likely have the best results. 

I’ll talk about exactly how much to add in a moment, but it’s important to understand that it’s not about the calorie burn or the fat burn during the exercise, but the hormonal and metabolic changes that happen after exercise. And I can’t emphasize enough that even given all this information about how exercise influences metabolism, if you’re eating in a calorie surplus, you likely aren’t going to see loss of fat mass. 

Can increasing step count contribute to leanness?

Again, without calorie restriction, increasing steps alone is not likely to result in significant weight loss. 

This study demonstrated that just increasing step count over 16 weeks resulted in around 3lbs of total weight loss. That is less than 0.2 lbs/week. 

Increasing your steps can, however, improve cardiovascular disease risk as well as overall health. And it may contribute to weight maintenance. 

So I’m not saying don’t do it. I’m just saying that the efficacy as far as weight loss goes is likely going to be limited. I still walk ~10-30 minutes/day, but I can tell you that I lost fat last year and did not change my step count at all. It was all nutrition for me. 

What should you focus on if leanness is your goal?

Based on all of this information, what are the takeaways? 

How much should you be doing if leanness is your goal? 

First, focus on diet. 

Just adding more exercise is not going to move the needle much unless diet is dialed in first. 

Second, it seems like a combination of cardio, a tiny bit of HIIT, and building muscle helps aid in leanness when diet is improved. 

Exercise may also help maintain leanness. 

Focus on building muscle and making sure that your sets are getting close to failure so you are emptying glycogen stores in your muscles and improving metabolic flexibility. 

Some HIIT is also beneficial for metabolic flexibility. I recommend 1-2 sessions per week that are all-out intensity. Keep them short (less than 20 minutes) start to finish. We do a 15-minute Cardio Burst in Evlo each week.

As far as cardio, incorporating 150 min/week in addition to strength training and HIIT is all you really need. If you like cardio and want to do more and honestly feel like you can recover from it, then go for it. 

Don’t track calories burned. Don’t even pay attention to that or add it to your overall daily burn. This can often lead to overeating or discounting a workout that could be very beneficial for improving that metabolic flexibility just because it didn’t burn as much. Remember, many strength workouts are not going to burn many calories. And even HIIT workouts likely won’t either since they are short. So get used to not paying attention to the calorie burn.
Even given all this information, I think we overemphasize the effect of exercise on fat loss and underemphasize diet’s effect. Exercise is not a great fat loss tool, but it may play a small part. Listen to this episode of Fit Body, Happy Joints where we will talk about diet and leanness.