Background:The health risks of obesity are disproportionately due to central abdominal adiposity; however, the extent to which age is associated with the body shape of obese adults is not known.Objective:Three-dimensional (3D) data on body shape from the UK National Sizing Survey were analyzed to investigate age-associated changes in body shape within the BMI bands <20, 20-24.99, 25-29.99 and >/=30 kg/m(2).Methods:Measurements of anthropometry (weight and height) and a 3D body scan were obtained in 4,344 men and 5,266 women recruited from eight British cities.Results:The body shape of men showed high consistency within BMI bands between early adulthood and old age. In contrast, the body shape of women altered within each BMI band with increasing age. In obese, overweight, and normal weight women, age was associated with decreased thigh girth, increased waist, and bust girth. Whereas young obese women maintained an hourglass shape, in old age the body shape of obese women converged on that of obese men.Discussion:The association of age with body shape is markedly different between the sexes, with the impact of obesity on shape strongly age-dependent in women but not in men. The age delay in the association between obesity and high waist girth in women may contribute to the sex-difference in life expectancy. The relationship between body shape change and cardiovascular risk merits longitudinal investigation within individuals.Obesity (2008) 16, 435-441. doi:10.1038/oby.2007.62