Exchanging carbohydrate or protein for fat improves lipid-related cardiovascular risk profile in overweight men and women when consumed ad libitum

• Published in: Journal of investigative medicine 2010-06, Vol.58 (5), p.711-719
• Main Authors: Kratz, Mario, Weigle, David S, Breen, Patricia A, Meeuws, Kaatje E, Burden, Verna R, Callahan, Holly S, Matthys, Colleen C, Purnell, Jonathan Q
• Format: Article
• Language: English
• ISSN: 1081-5589; 1708-8267
• DOI: 10.231/JIM.0b013e3181da4d37

BACKGROUNDThe impact of low-fat diets on the plasma lipoprotein profile is incompletely understood. METHODSWe conducted two 16-week dietary studies to compare the effects of a moderate-fat (mod-FAT) baseline diet with isocaloric and ad libitum low-fat diets rich in either carbohydrates (high-CHO, n = 16) or protein (high-PRO, n = 19) on plasma lipids, post-heparin lipase activities, cholesteryl ester transfer protein, and phospholipid transfer protein. RESULTSSwitching from the mod-FAT to the isocaloric high-CHO diet lowered plasma high-density lipoprotein cholesterol concentrations (P < 0.001) and tended to increase triglyceride levels (P = 0.087). Cholesterol content in the larger, buoyant low-density lipoprotein (LDL) fractions decreased, whereas those of the very-low-density lipoprotein, intermediate-density lipoprotein, and smaller, denser LDL fractions tended to increase. These changes were largely reversed when subjects lost weight by consuming this high-CHO diet ad libitum. Switching from the mod-FAT diet to the isocaloric high-PRO diet did not increase cholesterol content in the small-dense LDL fraction and led to decreases in both LDL and high-density lipoprotein cholesterol in plasma (P < 0.001 for both).Consumption of the high-protein ad libitum diet accompanied by weight loss did not change plasma lipids further, except for a shift of cholesterol from dense low-density lipoprotein fractions to more buoyant low-density lipoprotein fractions. Cholesteryl ester transfer protein concentrations decreased with high-cholesterol feeding, whereas cholesteryl ester transfer protein concentrations and hepatic lipase and phospholipid transfer protein activities all decreased during high-protein feeding. CONCLUSIONSBoth high-CHO and high-PRO diets improve plasma lipid-related risk of cardiovascular disease when consumed ad libitum.