Fat Loss Science
A closer look at the science of fat loss
In this edition of Momentum you’ll learn why it can be so easy to gain weight, the basic physiology of fat loss, why a calorie deficit is the key to fat loss, how to maintain muscle mass during a fat loss diet, and finally how to create your own fat loss diet.
Lose fat, build muscle.
The goal that trainers and coaches hear from their clients daily.
We’ve covered muscle building in a three part Momentum series, but now we’re diving into fat loss.
To set the stage, I want to focus on why I am saying fat loss and not weight loss.
Weight loss can happen if I get the flu and don’t leave the bed for a week. I’ll lose weight mostly due to water, maybe some muscle, and maybe some fat if I really don’t have an appetite.
I think its safe to say nobody wants to just lose water and muscle.
We want to shed the excess body fat while maintaining our hard earned muscle for a lean, healthier, defined, and athletic physique.
Here’s the thing: Fat loss is really simple. But, it is not easy.
To understand how to lose fat we need to understand why we gain fat. And to do that we have to go back… way back.
Evolution and Human Physiology
Food was not always as abundant and delicious as it is now.
Humans evolved over a 4-6 million year period. Farming wasn’t invented until around 12,000 years ago. Food wasn’t abundantly available to the masses until after the industrial revolution around 250 years ago.
So, for the vast majority of our time on this planet we needed to survive without much food.
We needed to hunt and gather to survive sometimes going days without food.
Humans evolved to have an amazing ability to store fat for future use because back in the day who knew when we would eat again.
Humans evolved to have seemingly never ending hunger signals that tell us to eat as much as possible because back in the day who knew when the next meal was coming.
An average man can store up to 100,000 calories of energy in our body tissues. We can survive on our stored energy for a long time because back in the day who knew when the next meal was coming. And while it is not a healthy thing to practice, humans can go weeks without food.
Fast forward a couple million years and put those humans in today’s world of food abundance and foods engineered to be hypercaloric and hyperpalatable and we have an obesity epidemic.
Now, there are a myriad of biological, psychological, social, governmental, and environmental factors that play into the obesity epidemic and unfortunately, this newsletter won’t solve it.
Food has become so readily available in the developed world that in the United States it is estimated that 300,000 deaths occur directly due to obesity and more from obesity related illnesses versus about 15,000 related to malnutrition, or starvation.
It is now estimated that 50% of the the US population will be obese by 2030.
What I’m trying to say is that the cards are stacked against us.
So, while I can’t solve the obesity epidemic I can help you, an individual reading this, be healthier by shedding excess body fat.
Basic Physiology of Fat Loss
Our metabolism is the sum of our anabolic reactions and our catabolic reactions.
Anabolic reactions are those that build things. Think building muscle, storing excess nutrients as fat, or storing carbohydrates in our muscles for later use.
Catabolic reactions are those that break things down. Think of muscle atrophy, burning fat for energy, or using stored carbohydrates for energy.
If we have more energy than we need, our body favors anabolism. If we want to gain muscle this is great because that energy goes towards packing on slabs of muscle. If the excess is beyond what we need for building muscle and replacing nutrients in our muscles, like glycogen, then we store fat in our adipose tissue.
If we consume less energy than we need, our body favors catabolism. We will have to use our stored energy, mainly fat, for body processes like maintenance of muscle and other basic body functions.
So, while there are many factors at play on either side of this equation it all comes down to:
Calories In vs. Calories Out
Plain and simple. But not easy.
This brings us to creating a calorie deficit.
The Caloric Deficit and Fat Loss
We need to consume less than we burn in order to lose fat.
Caloric restriction is going to be the single most important factor here because, unfortunately, exercise alone cannot create significant weight loss. More on this below.
Caloric restriction can happen a number of ways.
Which is why everybody you know has a different solution to weight loss.
You can count calories or macronutrients, you can do time-restricted feeding (intermittent fasting), you can do specific diets that make you eat less without realizing it by cutting out entire food groups (keto, Atkins, etc).
These methods have pros and cons.
Whatever method you choose for a fat loss diet, understand that caloric restriction is the primary mechanism by which you will lose weight.
So, calorie restriction is king here. The method that you choose to accomplish it is up to you. I teach you how to create your own fat loss diet in my free nutrition guide.
Now, before you go try whatever diet you just saw on TikTok I debunked many popular fad diets in this article.
Exercise and Fat Loss
Look at this image. Stare at it. Bask in it.
That is your total daily energy expenditure (TDEE).
That little box at the top, EAT, is how many calories we may burn in a day from exercise.
Exercise is not a significant portion of our daily caloric output.
While we do burn calories during our workouts, research headed by a gentleman named Herman Pontzer has shown that our body actually adapts our metabolism after a workout to burn fewer calories the rest of the day.
Now just because exercise is not a significant burner of calories like our Apple Watch says it is you should still exercise while trying to lose fat.
Physical exercise is one of the healthiest things we can do for our body. Not only will muscle burn more calories throughout the day than other tissues, but you should exercise to get stronger, improve your function, improve performance, improve your cardiorespiratory health, get smarter, and more.
When it comes to fat loss we should lift weights to build or maintain muscle because of its high metabolic rate and we should exercise for the physical adaptations we want in our body and for our general health.
Maintaining (or building?) Muscle while Losing Fat
You need to train hard with weights and eat enough protein to maintain your muscle during a fat loss diet.
And, some people who are beginners in the gym or have very high levels of body fat can actually build muscle while losing fat.
As far as training goes, basically the same training you did while gaining muscle should be the same kind of training you do while losing fat.
Training with high intensity (less than 5 reps in reserve) multiple times per week per muscle group (between 5-15 sets per muscle group) with a focus on progressive overload should be your fat loss, muscle preservation plan.
That said, since you are in a caloric deficit you may see some drop off in performance. That’s okay, since fat loss is the primary goal.
As far as protein consumption goes, aim for between 0.8-1.2 grams per pound of goal body weight per day.
This will ensure you keep as much muscle as possible while losing fat.
Fat Loss Diets are Not Forever
A fat loss diet is not how you should eat forever.
A fat loss diet should, however, create habits that make sustaining your fat loss simple.
In a meta-analysis of 29 long-term weight loss studies, more than half of the lost weight was regained within two years, and by five years more than 80% of lost weight was regained.
I don’t want that to be discouraging, even though it is, I want it to encourage you to pursue sustainability in your fat loss efforts.
Eating only celery for a month is not sustainable.
Eating mostly whole foods that are prepared at home is more sustainable.
I want people to understand that if you are trying to diet for fat loss you should do so in spurts. Go for a month or two or three at a time and then take a break to maintain. Repeat this process until your fat is lost.
This is highly individualized.
One person’s diet for fat loss may not look anything like your diet for fat loss.
Because of this fact, I put together this free guide to help people create their own sustainable fat loss diet.
Putting it All Together
Complex interactions between our biology, psychology, and environment cause us to gain excess fat. Through caloric restriction we can lose excess fat and through exercise we can maintain muscle during a fat loss diet. It is important to use methods that are sustainable to create long term habits for healthy eating.
Here is a reference guide to all the links posted throughout this article.
The Truth About Your Guru’s Favorite Diet
ISSN Position Stand on Protein Consumption
Questions about losing fat? Leave them in the comments below.