Intermittent Fasting After 60: Muscle Erosion and LDL Spikes Force Age-Specific Safeguards

A systematic review of 28 clinical trials (N=1,809 adults) published in Nutrients reveals intermittent fasting drives comparable weight loss across ages yet produces divergent body-composition and cardiometabolic effects. In participants over 60, up to 65% of lost mass derived from lean tissue rather than fat—an outcome that accelerates sarcopenia and frailty risk within months. This RCT-heavy meta-analysis (sample size >1,800, low heterogeneity for weight metrics) directly contradicts earlier observational reports assuming uniform fat loss. Parallel findings from an alternate-day fasting RCT (n=83, 6-month duration) showed that resistance training plus 1.6 g/kg protein preserved all lean mass while still yielding 5 kg fat loss and a 12% LDL drop, underscoring modifiable trade-offs the original coverage omitted. The Nutrients analysis further documented average LDL-C elevation across strata, prompting authors to recommend lipid surveillance—data that challenges prior assumptions of universal lipid improvement. For adults over 60, the combined muscle and cholesterol signals imply fasting protocols must incorporate strength training, protein timing, and quarterly lipid panels rather than default calorie restriction alone.