Muscle-Preserving Secrets Revealed: Exercise Boosts Metabolic Health During Weight Loss

According to a study published in November 2025, exercise during weight loss may have surprising benefits for muscle health, contrary to common assumptions. The research, conducted by a team of scientists, examined how the human body responds to a severe calorie deficit combined with regular aerobic exercise.

The study involved 10 healthy young men who underwent two five-day trials - one where they consumed enough calories to maintain their weight, and another where their daily calorie intake was reduced by 78%, a severe energy deficit. During both trials, the participants completed 90-minute low- to moderate-intensity cycling sessions three times.

The researchers found that despite the extreme calorie restriction, the muscle tissue mounted a strong and positive response. They observed an increase in the amount and production of mitochondrial proteins, which are crucial for converting fat and carbohydrates into usable energy. Additionally, the muscle showed a decrease in collagen-related proteins, which tend to accumulate with age and contribute to stiffness.

These changes suggest the muscle was becoming more metabolically efficient and youthful, even under the stress of a severe calorie deficit. The researchers believe this may be an evolutionary adaptation, as the ability to move efficiently during periods of low food availability would have been essential for human survival in the past.

The findings have important implications for people trying to lose weight, as well as athletes and older adults. The study indicates that structured exercise during weight loss may help preserve muscle quality and even enhance characteristics linked to healthier aging. As such, the researchers recommend that individuals incorporate exercise into their weight loss plans to support their overall metabolic health.