💪 Muscle building and obesity: Why excess fat may be holding your muscles back

People with obesity often have more muscle mass than those of a healthy weight—but that muscle tends to be lower in quality. This means they may not be able to perform as much physical activity per kilogram of muscle compared to their leaner peers.

A recent study looked at how young adults with obesity respond to strength training. After doing lower-body resistance exercises, participants ate a high-protein meal (170g of lean pork mince, containing 36g of protein). But despite this, their muscles didn’t build new protein as effectively as those of healthy-weight individuals.

Why? One likely reason is that people with obesity often have higher levels of insulin, even before eating or exercising. In this study, insulin levels were 2.5 times higher in the obese group before the intervention. This may interfere with the muscle-building process, making it harder for their bodies to repair and grow muscle after workouts.

In short, obesity may blunt the benefits of resistance training, even in young adults, by disrupting the body’s ability to build and repair muscle after exercise.

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Elevated insulin levels in people with obesity could interfere with the muscle-building process, making workouts less effective.

👴 Ageing doesn’t have to mean muscle loss: here’s why

It’s often believed that older adults naturally lose muscle because their bodies stop responding to exercise and protein as well as they used to—a condition known as “anabolic resistance.” But a new study challenges that idea.

Researchers compared healthy, lean young and older men who did resistance training and then consumed essential amino acids (the building blocks of protein). Surprisingly, both groups built muscle at similar rates after the workout. In fact, the older men had higher levels of amino acids in their blood and more of the proteins involved in muscle-building.

This suggests that ageing alone doesn’t cause muscle loss. Instead, it’s often the lifestyle changes that come with age—like being less active, eating poorly, or gaining excess body fat—that reduce the body’s ability to build muscle. Staying active, eating enough protein, and maintaining a healthy weight can help older adults keep their muscles strong well into later life.

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Older adults who stay lean, active, and eat enough protein can maintain their muscle-building ability just as well as younger people. The real culprit behind muscle decline in older adults are often lifestyle changes, not age itself.

😴 Muscle health: Why your muscles need sleep too

Did you know your muscles have their own ‘internal clock’?

This “muscle clock” helps manage how muscles grow and repair themselves. During the day, as you move around, your muscles build up damaged proteins. At night, while you sleep, the muscle clock kicks in to clean out those damaged proteins and refresh your muscles.

But when your body’s natural rhythm—your circadian rhythm—is disrupted, like with shift work or irregular sleep patterns, this clean-up process can get thrown off. That means damaged proteins stick around longer, which may lead to muscle weakening and signs of early ageing.

In a recent study using zebrafish (which share about 70% of their genes with humans), scientists found that when the muscle clock was disrupted, the fish aged faster. Within two years, they were smaller, weighed less, and swam slower and less often—clear signs of muscle decline.

While we can’t run these kinds of experiments on people for ethical reasons, the fish model gives scientists a good starting point. It suggests that people who regularly disrupt their sleep cycles—like shift workers—might also be at higher risk for losing muscle mass and strength earlier in life.

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Disrupting this natural cycle, as often happens with shift work, may quietly accelerate muscle loss and ageing.