Does Weight Loss ‘Damage’ Your Metabolism?

As you lose weight, a number of adaptations take place in the body to reduce your daily energy expenditure.

Most of these adaptations are normal and to be expected. For example, a smaller body burns fewer calories than a larger body, so the energy required to maintain your weight at the end of a diet will be less than the amount of energy needed to maintain weight at the start.

A smaller body also means you burn fewer calories when exercising. You’re also eating fewer calories, so the thermic effect of food (TEF) — the energy used to digest food — is also reduced.

Anyone who’s dieted for long enough can attest to the fact that energy levels drop. You start to move around less, both consciously and subconsciously. This can have a knock-on effect on non-exercise energy expenditure (NEAT), the component of your metabolism that refers to all the activity that isn’t formal exercise. (1)(2)

But there’s one adaptation that’s been at the centre of much controversy: Adaptive thermogenesis.

Adaptive thermogenesis (AT) is a greater than predicted drop in metabolic rate after weight loss, beyond what should be expected based on fat and fat-free mass changes.