Metabolic adaptation (or adaptive thermogenesis) is a physiological response. It has been greatly researched and shown to play a role in weight loss. Put simply, it is the body’s way of helping to preserve energy. Dieting down is perceived as a threat to survival and so the brain goes into defence mode.
Your body just loves being right where it is (homeostasis) When you enter a calorie deficit, your body wants to preserve as much as energy as possible because it isn’t getting as much energy (calories) as it was previously. If you have more calories available, you will burn more, if you have less available you will burn less. Your body does this by adapting and prioritising its needs in a hierarchy scheme of importance.
How can it affect my weight loss?
After a period of dieting down, your body will try to preserve energy as much as it can. The brain adjusts metabolic rate, hormone levels and behavior in order to resist weight loss. One way it will do this is by subconsciously making you do less NEAT (non activity thermogenesis) So for example, where you used to stand up you would now sit down, you will move around less in general and stop fidgeting. All of the little movements add up and so in turn you will be expending less calories. Your body has subconsciously made you preserve energy by USING LESS! It’s clever huh?!
How can I stop it?!
Firstly, this is normal! It is nothing to worry about and means that your body can respond to situations as they arise. It is also important to know that it is temporary. Your metabolism is not damaged or broken! It has adapted to its current situation that’s all!
It is also important to understand that metabolic adaptation will be different for everybody. The leaner you are and the longer you diet down for, the greater the chance of adaptation. In order to counteract this we use diet breaks and refeeds (more on this soon!) If you have finished your dieting phase, simply returning to maintenance calories or a small surplus will help you to recover.
Hope this helps! Sarah xx