Short diet changes shifted fat use during exercise in trained men
Diets differing in carbohydrate and fat produced opposite shifts in peak fat oxidation, without detected changes in measured muscle gene or protein expression.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
After brief dietary changes, trained men used fat differently during exercise: peak fat oxidation rose in the lower-carbohydrate group and fell in the higher-carbohydrate group. Muscle glycogen also shifted, while no changes in measured muscle gene or protein expression were detected. These laboratory findings do not establish changes in body fat or athletic performance.
The experiment was brief and included trained men. Its outcomes were fuel-use measurements and muscle markers; the abstract does not report changes in body fat or athletic performance.
What researchers found
Peak fat oxidation during exercise
After 3 days, it rose on the lower-carbohydrate diet and fell on the higher-carbohydrate diet versus each group's baseline; both within-group changes were statistically significant.
Measuring fuel use
Participants completed graded exercise tests before and after their assigned diets, alongside blood sampling and muscle biopsies. Researchers could therefore examine changes in exercise fuel use together with measurements taken directly from muscle.
Related muscle changes
Muscle glycogen fell with the lower-carbohydrate diet and rose with the higher-carbohydrate diet. The exercise intensity at peak fat oxidation shifted upward and downward, respectively, while measured muscle fat stores were similar after the diets.
The original publication
Divergent Changes in Peak Fat Oxidation and Fatmax Following 3-Day Dietary Interventions Are Related to Muscle Glycogen Availability in Men.
Tarry EK, Vestergaard SG, Petersen EA et al.
Scand J Med Sci Sports · 2025
- PubMed ID
- 40922559
- Record checked
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