You know you’ve reached middle age when weight loss becomes an uphill struggle. There are a multitude of factors stacked against us, not least a slowing metabolism and the shifts in hormones that typically contribute to wider hips in women and a paunch in men. Our activity levels typically begin a slow decline, and we naturally lose muscle mass so that the average middle-aged body is increasingly composed of fat.

Midlife weight gain occurs even if our lifestyle remains unchanged. A study from the Karolinska Institutet in Sweden published in the journal Nature Medicine last month, found that our lipid turnover — the rate at which we store and remove fat from our fat cells — slows with age.

Climbing is a great tool in combating weight gain GETTY IMAGES

For its trial, the Swedish team