The influence of intermittent fasting on body metrics, lipid profile, and physical performance in young and middle-aged men.
Maha Gasmi, Aymen Hawani, Anis Ben Chikha et al.
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In 30 seconds
This randomized controlled trial assessed five months of intermittent fasting, four days per week, in 40 active men aged 23–28 or 46–59 years. Compared with control groups, both fasting groups had significant reductions in weight, BMI and fat-free mass; weight showed a time-by-group interaction (p = 0.017). Total cholesterol and HDL also decreased in both age groups, while LDL decreased significantly only in younger men. Triglycerides and performance on a running-based anaerobic sprint test were not significantly affected. Body fat percentage did not change significantly.
Key findings
- Weight decreased in both fasting groups versus controls; the time-by-group interaction was significant (p = 0.017).
- BMI and fat-free mass decreased in both fasting groups; body fat percentage showed no significant change.
- Total cholesterol and HDL decreased in both fasting groups; LDL decreased significantly only in the young group (p = 0.041).
- Intermittent fasting did not significantly affect triglyceride levels or physical performance.
Why it matters
The findings suggest that, in active young and middle-aged men, intermittent fasting may alter weight and selected lipid measures without measurable improvement or decline in the tested anaerobic performance. The reductions in fat-free mass and HDL are relevant when interpreting the overall metabolic response; the study does not establish longer-term effects or broader applicability.
What to keep in mind
The trial included only 40 active men in two age groups and assessed a five-month intervention; applicability to other populations and longer-term outcomes is uncertain.