Mouse dietary interventions (western, ketogenic, low-protein longevity diet ± methionine supplementation, and bimonthly fasting-mimicking diet cycles) were compared for effects on fat mass, frailty, and cardiometabolic markers; findings were paired with a cross-sectional epidemiological analysis of >200,000 people examining animal protein intake and type 2 diabetes prevalence.
The methionine-supplemented low-protein longevity diet (LDMM) reduced fat mass and frailty, improved cardiometabolic markers, lowered IGF-1, and raised GH, GLP-1, and FGF21 (the latter required for fat loss and insulin sensitivity); high animal protein intake in humans was associated with ~2× the prevalence of type 2 diabetes vs. the lowest intake group.
Core mechanistic data are from mice, limiting direct human translation; the epidemiological arm is cross-sectional (cannot establish causation); high-animal-protein consumers may differ in unmeasured confounders despite lifestyle adjustment.
A mostly plant-based, low-amino-acid diet with moderate methionine intake may optimize healthspan while reducing frailty risk — a relevant trade-off to discuss with patients considering high-protein or ketogenic diets. Bimonthly short fasting-mimicking diet cycles offer an alternative strategy for improving metabolic markers.
