SERUM-LIPID RESPONSES TO A EUCALORIC HIGH-COMPLEX CARBOHYDRATE-DIET IN DIFFERENT OBESITY PHENOTYPES

Objective: To determine whether the eucaloric substitution of complex carbohydrates for dietary fat (15% of daily energy intake) affects pla sma lipid concentrations differently in upper-body obese, lower-body o bese, and nonobese women. Design: We studied 23 premenopausal women be fore and after dietary intervention. Material and Methods: After the 2 3 subjects achieved weight maintenance on their usual high-fat diet (4 3% fat, 37% carbohydrates, and 20% protein), the 7 upper-body obese, 8 lower-body obese, and 8 nonobese women consumed a eucaloric, high-com plex carbohydrate, low-fat diet (27% fat, 53% carbohydrates, and 20% p rotein) for 4 weeks in the Clinical Research Center. Before and after the high-carbohydrate diet, body composition and plasma lipids and apo proteins were measured. Results: After the high-carbohydrate diet, fas ting 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 bu t were not significantly changed in lower-body obese (1.37 +/- 0.28 mm ol/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 befor e the evening meal and throughout the night in upper-body obese women. Plasma cholesterol and high-density lipoprotein cholesteriol were not significantly affected by the change in diet. No changes in plasma ap oprotein concentrations or body composition occurred that could accoun t for the dietary-induced hypertriglyceridemia in the women with upper -body obesity. Conclusion: 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 import ance of assessing body fat distribution when treatment outcomes are de termined.