Why losing weight gets harder with age: studies reveal key factors

Many people find it increasingly difficult to lose weight as they get older, but recent studies indicate that this is not solely due to a slowing metabolism. Instead, a combination of physical and behavioral changes plays a significant role.

A study published in the journal Science found that, when accounting for body size and composition, energy expenditure remains stable between the ages of 20 and 60.

Experts explain that muscle mass is highest in one's twenties, which helps burn more calories. However, muscle begins to decline gradually from the mid-thirties at a rate of up to 1% per year without strength and resistance training.

Another study that tracked 963 people aged 38 to 50 over ten years found that daily sedentary time increased by about 40 minutes, while light physical activity decreased by around 30 minutes per day.

Other factors such as having children, working long hours, and eating late at night also contribute to weight gain.

Women in midlife experience hormonal changes that affect fat storage. A drop in estrogen leads to fat accumulating around the abdomen and waist. Hot flashes can also disrupt sleep quality, which in turn impacts hunger and stress hormones.

However, experts caution against blaming hormones alone, emphasizing the importance of physical activity and healthy eating habits.

After age 60, muscles become less responsive to protein—a phenomenon known as "anabolic resistance"—making it harder to maintain muscle mass.

Experts recommend that older adults consume 1.0 to 1.2 grams of protein per kilogram of body weight daily, with needs rising to 1.5 grams during illness.

The European Society for Clinical Nutrition and Metabolism also advises seniors to consume about 30 calories per kilogram of body weight each day.

Experts stress that the difficulty of losing weight with age is linked to muscle loss, reduced daily movement, dietary changes, and hormonal shifts—not just a slower metabolism. They recommend staying active, doing resistance exercises, and ensuring adequate protein intake.