Intermittent Fasting May Enhance Resistance Training Effects on the Body Composition of Obese Males, Without Affecting Muscular Strength and Anabolic Index.

Plain-language summary

This study tested whether pairing intermittent fasting with weightlifting improves body composition in obese men. It randomly assigned 20 obese men aged 20 to 30 to either a normal diet or 4:3 fasting (eating normally four days a week and sharply cutting calories on the other three), and both groups lifted three times a week for eight weeks. The fasting group lost about twice as much weight and fat, gained more in arm and chest size, and trimmed more off the waist. Both groups gained strength and held their anabolic index (the ratio of muscle-building testosterone to the stress hormone cortisol) steady, so fasting cost them nothing on that front.

Key findings

• The IF/RT group lost twice as much weight and fat as the regular diet group.
• The IF/RT group had larger arm and chest measurements and a smaller waist.
• Both groups improved muscle strength and testosterone levels equally.
• IF did not negatively impact the anabolic index (testosterone to cortisol ratio).