The effects of gender and age on associations between blood lipid levels and obesity in Danish men and women aged 35-65 years.

The purpose of the study was to assess the influence of gender and age on the associations between different measures of obesity, and blood lipid levels. Overall obesity (body fat, body fat percentage and body mass index) or abdominal obesity (waist/hip-ratio, waist/thigh-ratio and waist-circumference) and lipid levels [high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), total cholesterol and triglyceride level] were measured in 1987/88 in a random Danish population sample of men and women (N = 2987), aged 35, 45, 55 and 65 yr. All lipid levels were dependent on gender and age. The associations between most measures of obesity and HDL or LDL were independent of gender and age, whereas, with a few exceptions, associations between measures of obesity and total cholesterol, VLDL or triglycerides were dependent on gender and/or age. Compared to levels of HDL, LDL and total cholesterol, abdominal obesity specifically affected levels of VLDL or triglycerides, whereas overall obesity affected HDL, LDL, VLDL, total cholesterol and triglyceride levels more evenly. When men and women were compared, associations between the measures of obesity and blood lipids were stronger in men than in women of the same age, except for the associations between measures of abdominal obesity and VLDL or triglycerides in 45-year-old women. No age trend was found for associations between the measures of obesity and VLDL or triglycerides, whereas young age-groups showed stronger associations between obesity and total cholesterol than older age-groups. Failure to consider age/gender effects induces bias and may lead to misleading conclusions regarding the bivariate association between obesity and lipids, and further may make results from population studies incomparable.