USC researchers report modified Mediterranean diet lengthens mouse healthspan and cuts obesity risk

A study led by Valter Longo at the University of Southern California and collaborators at the University of Toronto and Harvard University found that a low‑protein, plant‑and‑fish‑based Mediterranean‑inspired diet supplemented with small amounts of the amino acid methionine improved health outcomes in mice. Mice fed this "longevity diet" lived longer, showed reduced frailty, lost fat while maintaining lean mass and ate more calories than control groups.

Analysis of health data from more than 200,000 people showed that higher consumption of animal protein, which supplies more methionine, was associated with higher rates of obesity and type‑2 diabetes, even when overall calorie intake was lower. Participants eating little or no animal protein had lower obesity and diabetes prevalence. The researchers suggest that the composition of amino acids, not just total protein or calories, may be a key factor in metabolic health and lifespan.

The findings were published in the journal Cell Metabolism and highlight a potential dietary strategy—referred to as a "longevity diet"—that emphasizes plant foods, fish, and limited methionine for improved cardiometabolic health.