Weight regain remains the Achilles heel of obesity treatment, with most dieters returning to baseline within years despite initial success. This challenge may not affect everyone equally—genetic factors could determine who maintains losses versus who struggles with rebounds. A comprehensive analysis of nearly 10,000 postmenopausal women reveals that genetic predisposition to obesity creates a stark divide in long-term weight maintenance outcomes. Using polygenic risk scores derived from genomic data of 2 million participants, researchers tracked weight trajectories over seven years following modest initial losses. Among European American women who successfully lost at least 5% of their body weight in the first year, those with the highest genetic risk scores (95th percentile) regained weight at nearly double the rate of women with average genetic risk—0.94 kilograms versus 0.48 kilograms annually. This finding represents more than statistical significance; it suggests fundamental biological differences in how bodies defend against sustained weight reduction. The effect was specific to European American participants, with no similar pattern observed in African American women, highlighting the complex interplay between genetics, ancestry, and metabolic regulation. From a clinical perspective, these results challenge the one-size-fits-all approach to weight management and point toward personalized strategies. Women with high polygenic risk scores may require more intensive long-term support, different intervention timing, or alternative therapeutic approaches to maintain losses. However, this remains a single study from one demographic group, and the mechanisms underlying genetic influence on weight regain require further investigation. The research opens intriguing possibilities for genetic screening to identify patients who might benefit from more aggressive maintenance protocols or novel therapeutic targets.