How do muscles respond to exercise during weight loss?

When we lose weight, we don’t just lose body fat – we lose muscle, too.

This can be a problem for many reasons, because skeletal muscle is far more than the tissue that helps us move. It plays a crucial role in metabolic health, regulating blood sugar and healthy ageing. Losing muscle mass is linked to a reduced mobility, increased injury risk and is thought to potentially impair long-term weight loss.

With millions of people now using weight loss drugs such as Wegovy and Ozempic, understanding what impact this muscle loss might have on their health is important.

Loss of muscle mass is also a significant challenge for athletes too, as many sports encourage them to keep body weight low while still maintaining demanding training loads and keeping their power-output high. So an energy deficit can put significant stress on an athlete’s body – but to what extent it affects their normal function, is unclear.

Yet despite these widespread implications, we still know surprisingly little about how human muscle responds at the molecular level to the combination of calorie restriction and exercise. Understanding what happens to muscle when exercising in a calorie deficit is extremely important.

Newly published research from myself and my colleagues casts light on this exact topic. We showed that weight loss accompanied...

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