Understanding Weight Regain

Weight loss isn’t the problem

Have you ever dieted only to get fatter than you were to start? If this hasn’t happened to you, you’ve certainly seen it happen to someone else because it is that common. The world obesity crisis has us thinking we have a weight loss problem. We don’t. We have a weight regain problem.

“One-third of lost weight tends to return within the first year, and the majority is gained back within 3 to 5 years.” Let that sink in for a minute. This is a direct quote from one of the most comprehensive reviews on the topic of weight regain written by MacLean et. al. We’ve linked it here for you guys if you’re interested in diving deep.

As a coach, a competitor and someone with an eating disorder background, this topic has always fascinated me. In my graduate studies, I dove deep into the current literature to learn more and directed my research around how different types of diets affected weight loss and weight regain.

There are times when weight regain is absolutely necessary. I cannot make that point more clear. Eating disorders like anorexia or purging disorders or competitive athletes making weight (think weight cut athletes, physique sports, etc.). This article is not suggesting every time you lose weight you should never gain any of it back. However, for the majority of people losing weight to achieve a healthy level of body fat (again, not competitive physique athletes), understanding how to maintain that weight lost and not regain it (and then some) is essential for long term health.


When you diet, you illicit adaptations that are normal but promote weight regain. Let’s use this as an example: You are 30 pounds overweight and have been for many years. That is your new settling point where your body is “comfortable” at (on a metabolic level). You now diet and lose said 30 pounds. Do you really think your body wants to sit there, comfortably, without a fight? Negative. From an evolutionary perspective, we were designed to store body fat to stave off periods of hunger so when it senses energy deprivation, a whole cascade of adaptations are kicked off. Additionally, when you diet you don’t lose fat cells, you simply shrink them. These now smaller fat cells are actually far more sensitive and are sending signals to your brain to eat and get back to where you were previously.

I say this not to be negative but to be honest. Understanding the biology behind what happens when we diet is critical to understanding what we can do about it.

The Physiological Adaptations to Dieting 

The physiological adaptations to dieting are real and pervasive, yet normal. These adaptations have your body primed to gain weight (preferentially body fat) after a harsh deficit. No, you do not have metabolic damage but you do have metabolic adaptations. Let’s dive deeper into the heavy hitters that promote weight regain on the physiological level.

Resting Energy Expenditure (REE)
This is your metabolism as a whole. If we’re looking at just REE, we see an overall reduction. But we need to split up REE into its four constituents to see where we are affected the most.

BMR/RMR: Basal or resting metabolic rate. This is your metabolism at rest aka how many calories you burn not doing anything. The difference between BMR and RMR is the nature of the measurement itself. BMR is a bit trickier to collect data because the subject needs to sleep overnight in the lab making it very impractical. RMR takes into account that you’ve likely driven to the lab, but good researchers/practitioners will make sure that you are in a calm state and fasted from any food. B/RMR will decrease with dieting. This makes perfect sense given that you weigh less as B/RMR is highly influenced by body weight. Your body simply burns less the less you weigh (and also the less muscle mass you have).

TEF: Thermic effect of feeding.  This is how many calories you burn digesting food. This will also go down simply from eating less. Certain foods like protein have a higher TEF than dietary fats, but in relative terms, TEF will decrease with less food.

EAT: Exercise activity thermogenesis. This is how many calories you burn during exercise. EAT is a bit less straightforward. From an absolute perspective, your EAT will likely go up during a diet if you are using any type of cardiovascular training to increase your calorie deficit. This is fairly common with most dieters. However, from a relative perspective, your body will adapt to the exercise stimulus for two major reasons: better economy (movement) during exercise and a lower body weight. Someone who weighs 150 pounds will burn less than someone who weighs 300 pounds.

NEAT: Non-exercises activity thermogenesis. This is how many calories you burn doing anything non-exercise related. Think fidgeting, moving around the house, dramatically telling a story, spontaneous activities… all of these things are ‘activity’ yet not considered exercises.  That being said, NEAT takes the absolute biggest hit during a diet. Studies have shown massive decreases in NEAT during weight loss and increases during weight gain. Other studies where subjects are overfed showcased how important NEAT was in how much weight was gained. Some participants barely gained any weight because they accounted for the extra calories by moving more while others had not changed their NEAT and gained significant amounts of weight. While most constituents of REE are largely affected by normal adaptations or from simply being at a lighter body weight, NEAT is 100% controllable and is largely determined by the person.

Hormonal changes 
Next up are the hormonal changes we see when dieting. Your individual response to dieting as well as the hormonal changes you see will be influenced by your genetics, age, lifestyle, training, and diet. However, these are the general trends we see with hormones while in a calorie deficit.

Thyroid hormone: Decreases. TH regulates your metabolism (primarily) but will naturally decrease as you diet simply as a by-product of less body weight.

Leptin: Decreases. Leptin is a hormone stored in fat cells that regulates our satiety. Since it is stored in fat cells, when body fat decreases, leptin decreases.

Ghrelin: Increases. Opposite to leptin, ghrelin is released to increase our hunger. Oh, joy!

Sex hormones: Decrease. The amounts vastly vary from individual and between the sexes but in general, sex hormones (testosterone, estrogen, DHEA, progesterone) will decrease when dieting.

Cortisol: Increase. Cortisol increases due to calorie restriction, increased exercise (namely cardio) and overall life stressors. Mismanaged cortisol can wreak havoc on muscle as it has a catabolic (think muscle loss) effect.

The only way to effectively manage blood markers is to get consistent blood work. Most insurance companies will not pay for the necessary or important blood panels people need. I completely avoid that mayhem and go straight to Life Extension. You pay out of pocket for any specific blood test you need, get the script online, have your blood drawn and the results are emailed to you. What is also great about Life Extension is that they have a highly educated staff of people just a phone call away you can consult with.

I have no affiliation with Life Extension besides I have been using their blood test services for years and have sent many of our Team LoCoFit clients to their site. If you are interested in a relevant, thorough blood panel for optimal health and body composition, this is the panel I recommend and personally use.


Knowing what you’re stacked up against is the half the battle. In the next installment of this article, I’ll go over the best ways to prevent excessive weight regain so you can maintain a healthy body composition where you are healthy, comfortable and confident.

Be the first to know

Get exclusive, no bullshit content from our coaches that is scientifically based and experience driven.