Spousal Resemblance and Risk of 7‐Year Increases in Obesity and Central Adiposity in the Canadian Population

KATZMARZYK, PETER T., LOUIS PÉRUSSE, D. C. RAO, AND CLAUDE BOUCHARD. Spousal resemblance and risk of 7‐year increases in obesity and central adiposity in the Canadian population. Obes Res . Objective : Spousal similarities in 7‐year changes in obesity and obesity‐related phenotypes were examined in a sub‐sample of 376 pairs of spouses from a sample of 1487 participants in the 1988 Campbell's Survey follow‐up of the 1981 Canada Fitness Survey. Measures : Indicators of body fatness included the body mass index (BMI), the sum of five skinfolds (SF5), and waist circumference (WAIST), whereas those for relative adipose tissue (AT) distribution included the ratio of two trunk to three extremity skinfolds, adjusted for SF5 (TER adj ), and WAIST adjusted for BMI (WAIST adj ). Results : Spouse correlations were 0. 17, 0. 17, and 0. 17 for the BMI ( p <0. 05) and 0. 20, 0. 20, and 0. 21 for SF5 ( p <0. 05) for the initial measurement, follow‐up, and 7‐year change, respectively. Spouse correlations for WAIST were somewhat lower: 0. 16 ( p <0. 05), 0. 11 ( p <0. 05), and 0. 11 ( p <0. 05) for the initial measurement, follow‐up, and 7‐year change, respectively, whereas those for TER adj and WAIST adj were low and not significant. Spouses of probands who had increases in adiposity and central AT distribution had elevated risks of also increasing in these parameters. Spousal risks (risk ratios) were 1. 48 (95% CI = 1. 08‐2. 03), 1. 49 (95% CI= 1. 10‐2. 02), and 1. 68 (95% CI= 1. 28‐2. 21) for increases in BMI, SF5, and WAIST, respectively, whereas the risks for increases in central adiposity were 1. 22 (95% CI = 0. 86‐1‐73), and 1. 05 (95% CI = 0. 72–153) for TER adj , and WAIST adj , respectively. Discussion : The results indicate significant spousal resemblance and risk for increases in fatness in the general Canadian population, whereas both the spousal resemblance and risks for increases in AT distribution, adjusted for level of fatness, are non‐significant. The results suggest that shared environmental factors may be important determinants of spousal similarities in changes in total body fatness over time; however, cohabitation in the short term may not lead to increases in spousal resemblance.