If you’re past a certain age, there’s a strong chance you have either thought it, or heard someone say it.

It may have happened when you felt particularly tired and achy, or more likely if you have put on a few unwelcome pounds from your 30s onwards.

You’ll know the seven words, or a variation of them: “It’s because my metabolism is slowing down.”

First things first, you are not alone – it’s certainly something I’ve uttered in response to the latest reading on my scales, without thinking twice about what it meant. No doubt I thought those changes indicated only one thing: the slow grind towards my eventual physical breakdown and inevitable death had begun.

But, while it’s true that your metabolism does indeed slow down as you age, this happens much later than you might expect – and it turns out we have much more control over our metabolism than you would think.