Rare gene tweak speeds metabolism, keeping some people naturally lean

A study of genetic data from over a million people identified a rare FNIP1 gene mutation that turns off calorie-burning pathways, helping about 1 in 7,000 individuals stay lean with lower body fat and healthier metabolic markers. Mouse experiments suggest turning off FNIP1 could inspire future weight‑loss therapies, but risks exist and any treatment would be years away.