Serum Lipid Responses to a Eucaloric High-Complex Carbohydrate Diet in Different Obesity Phenotypes

To determine whether the eucaloric substitution of complex carbohydrates for dietary fat (15% of daily energy intake) affects plasma lipid concentrations differently in upper-body obese, lower-body obese, and nonobese women. We studied 23 premenopausal women before and after dietary intervention. After the 23 subjects achieved weight maintenance on their usual high-fat diet (43% fat, 37% carbohydrates, and 20% protein), the 7 upper-body obese, 8 lower-body obese, and 8 nonobese women consumed a eucaloric, high-complex carbohydrate, low-fat diet (27% fat, 53% carbohydrates, and 20% protein) for 4 weeks in the Clinical Research Center. Before and after the high-carbohydrate diet, body composition and plasma lipids and apoproteins were measured. After the high-carbohydrate diet, fasting plasma triglyceride concentrations increased (from 1.50 ± 0.14 mmol/L to 2.00 ± 0.25 mmol/L; P = 0.04) in upper-body obese women but were not significantly changed in lower-body obese (1.37 ± 0.28 mmol/L and 0.96 ± 0.12 mmol/L) Or nonobese (0.70 ± 0.08 mmol/L and 0.73 ± 0.08 mmol/L) women. The hypertriglyceridemia was present before the evening meal and throughout the night in upper-body obese women. Plasma cholesterol and high-density lipoprotein cholesterol were not significantly affected by the change in diet. No changes in plasma apoprotein concentrations or body composition occurred that could account for the dietary-induced hypertriglyceridemia in the women with upper-body obesity. The hypertriglyceridemic response to a high-complex carbohydrate, low-fat diet may be obesity phenotype specific. These findings suggest that further studies of this phenomenon should be focused on this obesity phenotype and further emphasize the importance of assessing body fat distribution when treatment outcomes are determined.