Obesity spectrum defined by the new Lancet framework and life expectancy free of major chronic diseases in UK adults: a multistate life-table analysis

Background The conventional BMI-based diagnostic paradigm for obesity fails to accurately reflect adiposity and associated health risks. The Lancet Diabetes & Endocrinology Commission proposed a novel classification framework in 2025 to address these limitations. Yet, the impact of obesity phenotypes on disease-free life expectancy remains uncharacterized, limiting evidence-based healthcare resource allocation. Purpose To evaluate associations of obesity phenotypes defined by the 2025 Lancet framework with disease-free life expectancy (free from CVD, diabetes, cancer, and dementia) among UK adults. Methods Using UK Biobank data from adults free of major chronic diseases at baseline, participants were classified into four obesity phenotypes: non-obesity (with/without organ dysfunction), preclinical obesity, and clinical obesity. Sex-specific multistate life tables were used to calculate the total life expectancy and years lived with and without major chronic disease. Results Among 428,878 participants, 89,325 (20.8%) were classified as non-obesity without organ dysfunction, 76,308 (17.8%) as non-obesity with organ dysfunction, 84,156 (19.6%) as preclinical obesity, and 179,089 (41.8%) as clinical obesity. At age 50 years, the estimated disease-free years were 28.5 (95% CI, 28.2-28.7), 25.4 (24.9-25.7), 25.9 (25.5-26.3), 22.0 (21.6-22.3) for men in non-obesity without organ dysfunction, non-obesity with organ dysfunction, preclinical obesity, and clinical obesity status, respectively; the corresponding estimated disease-free years at age 50 years for women were 33.6 (33.5-33.8), 30.7 (30.4-31.0), 31.2 (30.9-31.6), and 26.6 (26.3-26.9) (Figure 1). Compared with non-obesity without organ dysfunction, 50-year-old men with preclinical and clinical obesity lost 2.6 and 6.5 years of disease-free life expectancy, respectively; the corresponding lost years for women were 2.4 and 7.0. Compared with non-obesity without organ dysfunction, men with preclinical and clinical obesity lived 1.9 and 4.1 additional years with chronic disease, respectively; corresponding estimates for women were 1.8 and 5.4 years (Figure 1). These differences attenuated but remained significant at older index ages (60 and 70 years) (Figure 1). Notably, reductions in disease-free life expectancy associated with preclinical and clinical obesity persisted across socioeconomic strata (Figure 2). Conclusions Preclinical and clinical obesity phenotypes are both associated with reduced disease-free life expectancy, with clinical obesity showing the most pronounced impact, regardless of sex and socioeconomic status. These findings support early intervention to prevent disease progression from preclinical to clinical obesity and targeted treatment for clinical obesity to reduce individual and healthcare system burden.Figure 1Figure 2