Is adiposity at normal body weight relevant for cardiovascular disease risk?

OBJECTIVE: To examine the relation between adiposity and risk factors for cardiovascular disease (CVD) in normal weight (NW) individuals. METHODS: Cross-sectional study using the sample of white people, aged from 17 to 60y from the Québec Family Study and the Heritage Family Study. NW subjects with a body mass index (BMI) between 18.5 and 25 kg/m² (181 males and 265 females) and overweight (OW) subjects with a BMI between 25 and 30 kg/m² (133 males and 114 females) were retained for this study. NW subjects were divided into quintiles of each adiposity variable, then the quintiles and the OW group were evaluated for the presence of CVD risk factors. Using logistic regression analysis, the odds ratio (OR) for the prevalence of risk factors for each quintile of each adiposity variable and the OW group was estimated relative to the first quintile in NW subjects. Mean values of adiposity variables were compared between the subjects with and without risk factors. In these analyses, age and study cohort effects were taken into account. MEASUREMENTS: Percentage body fat (%fat) and fat mass (FM) measured by underwater weighing were available as adiposity variables. Risk factors included systolic and diastolic blood pressure, LDL and HDL cholesterol, triglycerides and fasting glucose. RESULTS: Wide ranges of values were observed for adiposity variables. HDL cholesterol, triglycerides and fasting glucose in NW males and HDL cholesterol in NW females were significantly correlated with all adiposity variables. For males, higher quintiles of adiposity variables in the NW group and the OW group tended to have higher ORs compared to the first quintiles for the risk factor variables. The fifth quintiles of all adiposity variables had the highest ORs (3.15 for %fat and 3.77 for FM) and they were significantly different from the first quintiles. OW males had ORs similar to those of the fifth quintiles for the risk factor variables. On the other hand, for females, the relatively linear associations were less clear in the NW group. In NW males, the subjects with at least one risk factor had significantly higher %fat and FM than the subjects without risk factors, in NW females, no significant difference was observed for these adiposity variables between the subjects with and without risk factors. CONCLUSION: NW males with elevated adiposity had higher prevalence of risk factors than NW males with less adiposity and the prevalence in the former was rather similar to that seen in OW males. On the other hand, measures of adiposity added little additional information to the BMI classification of NW on CVD risk factors in females.