When older mice lose weight by eating less, they lose muscle regardless of whether they eat high-fat, high-carb, or high-protein food—and they all regain the same amount of muscle when eating freely again.
Evidence from Studies
No evidence studies found yet.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Whether protein intake during caloric restriction and refeeding consistently preserves muscle mass in aging mammals, independent of total energy intake.
A systematic review and meta-analysis of 20+ controlled feeding studies in aging humans and rodents comparing high-protein (>30% kcal), moderate-protein (15–20% kcal), and low-protein (<10% kcal) diets during CR and refeeding, with standardized muscle mass measurements (DXA, hydroxyproline, or dissection) as primary outcomes.
Whether high-protein diets preserve muscle mass during caloric restriction and refeeding in aging mice when energy intake is matched.
A double-blind RCT in 90 aging C57BL/6J mice undergoing 4-week 30% CR, randomized to isocaloric high-protein (40% kcal), moderate-protein (20% kcal), or low-protein (10% kcal) diets, with muscle mass measured via dissection of hindlimb muscles at CR end and refeeding end.
Whether protein intake during refeeding predicts muscle mass recovery in aging mice after caloric restriction.
A prospective cohort study of 120 aging mice undergoing 4-week CR and 8-week refeeding, with daily protein intake recorded and muscle mass measured weekly via dissection, testing if protein intake predicts muscle recovery after adjusting for total energy.
Whether mice with higher protein intake during refeeding have greater muscle mass at a single time point.
A cross-sectional analysis of 100 aging mice at the end of 4-week refeeding, measuring daily protein intake and hindlimb muscle mass via dissection, stratified by diet group to test for association.
Whether individual mice with very high protein intake during refeeding show exceptional muscle recovery.
Detailed case series of 10 aging mice with protein intake >50% kcal during refeeding and muscle mass >1.2 g, documenting daily intake and muscle mass to identify outliers.