Early-Life Sugar Restrictions Reduce Genetic Disparities in Adult Adiposity

Genetics confer 2–3-fold higher obesity risk through inherited mechanisms affecting appetite and metabolism, with pathways particularly modifiable during the first 1,000 days of life. We leverage the end of UK sugar rationing in September 1953, a sharp discontinuity in early-life sugar exposure by conception date, to examine whether sugar restriction mitigates genetically determined obesity risk using UK Biobank data linking an obesity polygenic index with adiposity phenotypes. Without rationing, high genetic risk individuals had triple the obesity prevalence of low-risk counterparts. Restriction through age two narrowed this disparity by 40%, operating through visceral rather than general adiposity, and was concentrated among high-risk adults with above-median adiposity levels. Early nutritional environments can alter inherited obesity trajectories, pointing to targeted early-life interventions to reduce genetically determined health inequalities.