Familial risk of obesity and central adipose tissue distribution in the general Canadian population

The purpose of this study was to determine the familial risk of obesity and of an android profile of fat distribution in the general Canadian population. A sample of 15,245 participants aged 7-69 years from 6,377 households from the Canada Fitness Survey of 1981 was used. The body mass index (BMI), sum of five skinfolds (SF5), ratio of trunk-to-extremity skinfolds, adjusted for SF5, and waist circumference, adjusted for BMI were used as indicators of obesity and central fat distribution. Age- and sex- standardized risk ratios (SRRs) for spouses and first-degree relatives of obese probands indicate that there is significant familial risk for obesity and an android fat distribution in the Canadian population. SRRs for spouses and first-degree relatives of probands exceeding the 99th percentile are 3.01 and 4.96 for BMI, 7.36 and 4.15 for SF5, 1.41 and 3.18 for ratio of trunk- to-extremity skinfolds, adjusted for SF5, and 1.02 and 2.18 for waist circumference, adjusted for BMI, respectively. The SRRs are smaller for less extreme obesity (lower percentile cutoffs) than for more extreme obesity. The SRRs are greater in spouses than in first-degree relatives for SF5; however, the risk for BMI and an android fat distribution was greater among first- degree relatives than among spouses, suggesting a greater role for genetic factors.