To evaluate long-term patterns of weight change and progression to overweight and obesity during adulthood.

Prospective study. Changes in mean BMI, waist circumference (WC) and weight were assessed over a mean 26-year follow-up (1971–1975 to 1998–2001). Mean BMI (95 % CI) and mean WC (95 % CI) of men and women in BMI and age groups were computed. Mean weight change in BMI and age categories was compared using analysis of covariance.

Framingham Heart Study Offspring/Spouse Nutrition Study.

Men and women (n 2394) aged 20–63 years.

During follow-up, increases in BMI (men: 2·2 kg/m2; women: 3·7 kg/m2) and WC (men: 5·7 cm; women: 15·1 cm) were larger in women than men. BMI gains were greatest in younger adults (20–39 years) and smallest in obese older adults (50–69 years). The prevalence of obesity doubled in men (to 33·2 %) and tripled in women (to 26·6 %). Among normal-weight individuals, abdominal obesity developed in women only. The prevalence of abdominal obesity increased 1·8-fold in men (to 53·0 %) and 2·4-fold in women (to 71·2 %). Weight gain was greatest in the youngest adults (20–29 years), particularly women. Gains continued into the fifth decade among men and then declined in the sixth decade; in women gains continued into the sixth decade.

Patterns of weight change and progression to obesity during adulthood differ in men and women. Preventive intervention strategies for overweight and obesity need to consider age- and sex-specific patterns of changes in anthropometric measures.