The association between obesity in adults and excess morbidity and mortality is well established, but the impact of being obese in early adulthood on health throughout adult life needs elucidation. We investigated the all-cause mortality until 80 years of age in men starting adult life as obese.
Among 362,200 Danish young men, examined for military service between 1943 and 1977, all obese (defined as body mass index (BMI = 31.0 kg m(-2)), and, as controls, a random 1% sample of the remaining population were identified. A total of 1862 obese, corresponding to all men above the 99.5 percentile in this population, and 3476 controls were included, at a median age of 19 years (range: 18-25 years of age). They were followed until 2007 and Cox regression models were used to estimate the mortality in the obese relative to the controls. In addition, two reference groups were used: normal weight men (BMI: 18.5-24.9 kg m(-2)) and the men with the lowest mortality in this cohort (BMI: 22.0-24.9 kg m(-2)).
During the 65 years of follow-up, 1191 men died. At all ages from 18 to 80 years, the mortality in the obese was twice that of the controls (hazard ratio (HR): 2.10; 95% confidence interval (CI): 1.84-2.39). The median survival proportion (0.5) was reached about 8 years earlier in the obese than in either of the reference groups. Relative to the normal weight and men with the lowest mortality HRs of 2.14 (95% CI: 1.86-2.45) and 2.38 (95% CI: 2.00-2.85), respectively, were estimated for the obese. Neither year of birth nor education significantly influenced the excess mortality.
Men entering adult life as obese experience a lifelong doubling of mortality, a finding that strongly supports the continued need to avoid beginning adult life as obese.