Association between Mild Overweight and Survival: A Study of an Exceptionally Long-Lived Population in the Sardinian Blue Zone

Background/Objectives: Overweight and obesity are generally considered risk factors for premature mortality. However, scientific evidence suggests that among older populations, mild conditions of overweight might be associated with reduced comorbidity and longer survival. This study investigates the potential association between anthropometric parameters and survival among a cohort of nonagenarians in Sardinia, Italy. Methods: This study included 200 subjects (50% females) aged 89 and older, enrolled in 2018 in the Sardinian Blue Zone-a population known for longevity-and followed for up to six years. Anthropometric variables such as body height, weight, age, sex, comorbidity, disability, and food group intake were collected using validated questionnaires and analyzed through multivariable analysis. Results: Out of 200 participants at baseline, 28 (14%) were still alive after six years of follow-up (females 10%, males 18%). Mean survival was 3.36 years (range 0.1-6.9 years) for males and 3.03 years (range 0.2-6.6 years) for females. Participants with a Body Mass Index (BMI) in the range of 25.0-27.0 kg/m2 among males and 25.0-27.2 kg/m2 among females had longer survival compared to those who were underweight (p = 0.002) or obese (p < 0.0001). The Cox proportional hazards regression model, adjusted for age, sex, and comorbidity, revealed a statistically significant association between the BMI and survival, demonstrating an inverted-U relationship. This indicates that mild overweight was associated with a survival advantage compared to both normal weight and obesity. Conclusions: Our study indicates that mild, but not severe, overweight in nonagenarians is associated with extended lifespan. Therefore, primary care physicians and geriatricians should exercise caution before recommending calorie-restricted diets for mildly overweight elderly patients.