Effects of obesity and body fat distribution on lipids and lipoproteins innondiabetic American Indians: The Strong Heart Study

Objectives: To examine the relationship between obesity and lipoprotein pro files and compare the effects of total obesity and central adiposity on lip ids/lipoproteins in American Indians. Research Methods and Procedures: Participants were 773 nondiabetic American Indian women and 739 men aged 45 to 74 years participating in the Strong H eart Study. Total obesity was estimated using body mass index (BMI). Centra l obesity was measured as waist circumference. Lipoprotein measures include d triglycerides, high-density lipoprotein (HDL) cholesterol, low-density li poprotein (LDL) cholesterol, apolipoprotein AI (apoAI), and apolipoprotein B (apoB). Partial and canonical correlation analyses were used to examine t he associations between obesity and lipids/lipoproteins. Results: Women were more obese than men in Arizona (median BMI 32.1 vs. 29. 2 kg/m(2)) and South Dakota and North Dakota (28.3 vs. 28.0 kg/m(2)), but t here was no sex difference in waist circumference. Men had higher apoB and lower apoAI levels than did women. In women, when adjusted for center, gend er, and age, BMI was significantly related to HDL cholesterol (r = -0.24, p < 0.001). There was a significant but weak relation with apoAI (r = -0.14, p < 0.001). Waist circumference was positively related to triglycerides (r = 0.14, p < 0.001) and negatively related to HDL cholesterol (r = -0.23, p < 0.001) and apoAI (r = -0.13, p < 0.001). In men, BMI was positively corr elated with triglycerides (r = 0.30, p < 0.001) and negatively correlated w ith HDL cholesterol (r = -0.35, p < 0.001) and apoAI (r = -0.23, p < 0.001) . Triglycerides increased with waist circumference (r = 0.30, p < 0.001) an d HDL cholesterol decreased with waist circumference (r = -0.36, p < 0.001) . In both women and men there was an inverted U-shaped relationship between obesity and waist with LDL cholesterol and apoB. In canonical correlation analysis, waist circumference received a greater weight (0.86) than did BMI (0.17) in women. However, the canonical weights were similar for waist (0. 46) and BMI (0.56) in men. Only HDL cholesterol (-1.02) carried greater wei ght in women, whereas in men, triglycerides (0.50), and HDL cholesterol (-0 .64) carried a large amount of weight. All the correlation coefficients bet ween BMI, waist circumference, and the first canonical variable of lipids/l ipoproteins or between the individual lipid/lipoprotein variables and the f irst canonical variable of obesity were smaller in women than in men. Trigl ycerides and HDL cholesterol showed clinically meaningful changes with BMI and waist circumference in men. All lipid/lipoprotein changes in women in r elation to BMI and waist circumference were minimal. Discussion: The main lipoprotein abnormality related to obesity in American Indians was decreased HDL cholesterol, especially in men. Central adiposit y was more associated with abnormal lipid/lipoprotein profiles than general obesity in women; both were equally important in men.