You’ve been doing hours of cardio every week for months on end.
You’re eating what you think are all the right things.
All the online calculators say that you’re in a calorie deficit, and that you should be losing fat.
But you’re not.
You’ve hit a weight loss plateau, and you can’t get past it no matter how hard you try.
You’re hungry all the time and can’t stop thinking about food.
The thought of carrying on like this just to maintain your current weight is about as appealing as packing up all your belongings and moving to Syria.
So, what’s going on?
Firstly, I should point out that there are many potential reasons why your weight loss has stalled.
Many times, the culprit is a dip in your activity levels.
Sometimes it’s because you’re not sticking to your diet as closely as you think you are.
However, it’s also true that your metabolism can adapt to a program of diet and exercise in such a way that it makes continued fat loss increasingly difficult.
The number of calories your body burns both at rest and during physical activity is linked to your weight. When you lose weight, your body is smaller. And a smaller body has smaller energy requirements than a larger one.
There is also a drop in energy expenditure that’s not accounted for by changes in weight and body composition.
Think of it like this.
Take two identical twins. One of the twins gains fat over a period of several years. He then drops the fat so he weighs the same as his leaner brother.
All other things being equal, the formerly fat twin is going to have a lower resting metabolic rate than the one who stayed lean.
In scientific lingo, this difference in resting metabolism is known as adaptive thermogenesis.
You might also see it called a metabolic shift… metabolic adaptation… metabolic dysregulation… metabolic damage… or some other variation on the theme.
It’s defined as the “decrease in energy expenditure beyond what can be predicted from body weight or its components under conditions of standardized physical activity in response to a decrease in energy intake.”
When observed, it’s been found to range from as little as 79 to as much as 504 calories per day beyond what is predicted from the amount of weight lost .
In short, what it means is that the number of calories your body burns at rest is going to drop.
However, the extent to which it drops can vary widely from person to person.
In one study, researchers from Rockefeller University Hospital and The New York Presbyterian Medical Center looked at how the metabolism changes in response to weight loss .
The drop in resting metabolic rate beyond what was predicted based on changes in body composition alone averaged around 150 calories per day.
However, the group average masks a large difference in results from person to person.
In other words, some people will go on a diet and see very little change in their resting metabolic rate.
For others, the drop is large enough to offset a sizeable chunk of the calorie deficit created by that diet.
This metabolic adaptation also seems to persist for some time, possibly for life.
Six years after losing massive amounts of fat on the reality TV show “The Biggest Loser,” most contestants in a recent study had regained much of the lost weight . Yet their resting metabolic rate was still lower than it was before losing the weight.
However, none of this means that your metabolism is damaged.
The term “damage” is somewhat misleading, as it implies that something is broken and needs to be repaired.
Although it varies from person to person, a degree of metabolic adaptation is completely 100% normal – a naturally occurring response designed to keep you alive when food is in short supply.
Sensing a reduction in the availability of food, your body turns down the rate of heat production in order to conserve energy.
It certainly doesn’t mean that you’ve “killed” your metabolism, messed up your diet, or done anything wrong.
SEE ALSO: THE FLAT BELLY CHEAT SHEET
If you want less flab and more muscle when you look down at your abs (or where they should be), check out The Flat Belly Cheat Sheet.
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ABOUT CHRISTIAN FINNChristian Finn holds a master's degree with distinction in exercise science, is a former personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Fit Pro, Zest, and Perfect Body magazine.
1. Rosenbaum M, Hirsch J, Gallagher DA, Leibel RL. (2008). Long-term persistence of adaptive thermogenesis in subjects who have maintained a reduced body weight. American Journal of Clinical Nutrition, 88, 906-912
2. Fothergill E, Guo J, Howard L, Kerns JC, Knuth ND, Brychta R, Chen KY, Skarulis MC, Walter M, Walter PJ, Hall KD. (2016). Persistent metabolic adaptation 6 years after “The Biggest Loser” competition. Obesity, May 2, Epub ahead of print
3. Helms ER, Aragon AA, Fitschen PJ. (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition, 11, 20