Body shape in American and British adults: between-country and inter-ethnic comparisons

Background: Recent studies indicate differences between British and American white adults, and between income and ethnic groups within the United States, in the population distribution of lifestyle diseases. Differential prevalence of obesity has been suggested as a contributing factor; however, the conventional approach to categorizing obesity, body mass index, is confounded by ethnic variability in physique. Objective: To compare indices of shape between white British and American adults, and between white, African and Hispanic American adults. Design: Analysis of two large National Sizing Surveys, using identical study design and three-dimensional (3D) body-scanning instrumentation, on adults aged 17+ years from the UK (3907M and 4710F white), and from the USA (1744M and 3329F white, 709M and 1106F African and 639M and 839F Hispanic). Outcome measures: Weight, height, body circumferences. Results: In the United States, socio-economic status was associated with increasing height and decreasing waist girth in white and Hispanic, but not African Americans. Compared to white British, white Americans had larger weight and girths, especially waist girth in men. Relative to white Americans, African Americans had smaller relative waist girth, but larger thigh girth, whereas Hispanic Americans had larger relative waist girth. Conclusions: Body shape of white American adults differs from that of their UK counterparts. Within Americans, ethnic differences in body shape closely track reported differences in prevalence of the metabolic syndrome, implicating variability in central abdominal fat as a key contributing factor. 3D photonic scanning offers a novel approach for categorizing risk of the metabolic syndrome and monitoring treatment success.