Methionine-supplemented low-protein diet in mice: growth hormone, GLP-1, FGF21 and frailty
In mice, a low-protein longevity diet supplemented with methionine reduced fat mass and frailty and improved cardiometabolic markers; it lowered IGF-1 and raised growth hormone, GLP-1 and FGF21. An epidemiological cross-sectional analysis linked highest animal protein intake to about double the prevalence of type 2 diabetes. [1]
Automatic summary · not editorially reviewed
The key findings
In mice, western and ketogenic diets increased fat mass and frailty, whereas a low-protein longevity diet supplemented with methionine reduced fat mass and frailty and improved cardiometabolic markers. [1]
The methionine-supplemented diet lowered IGF-1 and raised growth hormone, GLP-1 and FGF21; FGF21 was required for fat loss and insulin sensitivity. [1]
In a cross-sectional analysis of over 200,000 men and women, the highest animal protein intake group had approximately double the prevalence of type 2 diabetes compared with the lowest intake group. [1]
The source at a glance
- Study type / format
- Animal diet study plus cross-sectional epidemiological analysis (abstract)
- Population / context
- Mice fed different diets, plus over 200,000 men and women in an epidemiological cross-sectional analysis.
- Summary based on
- Study abstract
- Original publication
- June 23, 2026
Diets tested in mice for healthspan and strength
The researchers examined different diets to find compositions that promote both healthspan and strength in mice. The western and ketogenic diets increased fat mass and frailty and raised either cholesterol or insulin resistance. A low-protein longevity diet modeled on the traditional Mediterranean and Okinawan diets, but supplemented with methionine (LDMM), instead reduced fat mass and frailty while improving cardiometabolic markers.
Supporting source [1]
Hormone changes and FGF21 requirement in LDMM mice
LDMM reduced insulin-like growth factor 1 (IGF-1) while increasing growth hormone, GLP-1 and fibroblast growth factor 21 (FGF21). FGF21 was required for the fat loss and insulin sensitivity seen with this diet. Separately, bimonthly cycles of a 4-day fasting-mimicking diet improved metabolic markers.
Supporting source [1]
Animal protein intake and type 2 diabetes prevalence
A cross-sectional analysis of epidemiological data from over 200,000 men and women found that those with the highest animal protein intake tended to have a healthier lifestyle but had approximately double the prevalence of type 2 diabetes compared with the lowest intake group. The authors conclude that mostly plant-based low-amino-acid diets have the most potent effects on healthspan but require moderate methionine intake to minimize frailty.
Supporting source [1]
How to interpret this
Abstract only; the full text was not reviewed. The diet and hormone findings come from mice, not humans, and do not establish human lifespan or healthspan benefits. The epidemiological result is a cross-sectional association, not evidence of cause and effect.
Based on the study abstract; the full paper, tables and supplementary data were not reviewed.
Source & supporting passages
Fanti M, Brandhorst S, Navarrete G, Diaz A, Giuliani G, Chowdhury D, Antunes GC, Morgan TE, Dubeau L, Villani V, Perin L, Malik VS, Hu FB, Longo VD. · europepmc.org · June 23, 2026