Systematic Review Reveals How Intermittent Fasting Enhances Fat Loss Without Losing Muscle - Video

A new study published in the International Journal of Obesity highlights the added benefits of combining intermittent fasting with regular exercise. Conducted by researchers from the University of Mississippi, the study concludes that pairing time-restricted eating—specifically an eight-hour eating window—with physical activity leads to greater fat loss and a reduction in body fat percentage, all while preserving lean

muscle mass.

The research team, led by Wijayatunga and Michael Hays—a tactical dietitian and recent university graduate—conducted a systematic review and meta-analysis of 15 studies from the past decade. These studies explored various forms of intermittent fasting, but this analysis focused on time-restricted eating, one of the most popular formats due to its perceived simplicity. The results, though promising, were seen in already healthy and physically active individuals.

“We saw that this did lead to more fat loss and reduced body fat percentage over time when healthy adults were following both exercise with time-restricting eating, compared to those who were only exercising for at least 4 weeks. It is important to note lean mass preservation,” said Nadeeja Wijayatunga, assistant professor of nutrition and hospitality management.

“In most cases, these were healthy adults. They were already physically fit and already had exercise routines. When you already have athletic, lean people and you decrease their body fat percentage, that’s significant,” Hays noted.

One of the main concerns with fasting diets is the potential loss of lean mass, which is crucial for metabolism and overall mobility but this study offers reassurance.

Reference: Hays, H.M., Sefidmooye Azar, P., Kang, M. et al. Effects of time-restricted eating with exercise on body composition in adults: a systematic review and meta-analysis. Int J Obes (2025). https://doi.org/10.1038/s41366-024-01704-2