Understanding metabolic adaption

Metabolic adaption refers to the decrease in energy expenditure associated with a decrease in body weight.

If you had only come across the term in magazine or news articles, it has probably been represented in a negative light as the cause of weight regain and/or an inescapable roadblock to sustained weight loss.

However, when we break down metabolic adaption to see what it really is, we realise that it’s simply part of the weight loss process and not necessarily something that will halt longer-term progress.

To put it simply, some components of energy expenditure decreases as we lose weight because there is less weight to carry, tissue to maintain and food consumed.

But this doesn’t necessarily mean that total energy expenditure decreases as a result.

Losing 10kg might lead to less energy expenditure from a 5km walk, but it often means we can walk faster, further, or more frequently.

The thermic effect of food might decrease in line with food intake, but the lesser amount of calories also helps facilitate an energy deficit.

It’s really the bit about Basal Metabolic Rate that can be used to prey on our fears - the fact that we are now burning less energy at rest.

This is true - basal metabolic rate decreases in line with body weight, which means less energy expenditure if you were to lie in bed all day and do nothing (compared to pre-weight loss).

Anyone who loses 10kg will also see a decrease in BMR.

However, the 10kg decrease in weight often leads to significant increases in energy expenditure through exercise and also facilitates dietary adherence, because it demonstrates that the system works.

When viewed in isolation, metabolic adaption can seem unfair and make it seem like any weight loss attempt is doomed.

But to say it halts weight loss often fails to consider the flip side of any potential decreases in energy expenditure and even outweigh them.

So if you think metabolic adaptation is a bad thing, or know someone who does, this week might just clear a few things up.

Tom Fitzgerald