Exercise prevents the augmentation of postprandial lipaemia attributable to a low-fat high-carbohydrate diet.

Abstract

There is concern that replacement of dietary fat with carbohydrate may not reduce the overall risk of CHD because this replacement strategy elevates postprandial plasma triacylglycerol (TAG) concentrations. The present study was designed to test the hypothesis that daily exercise can offset the augmented postprandial lipaemia associated with a short-term high-carbohydrate diet. Nine healthy, normolipidaemic men aged 33 (sd 4) years consumed a test meal (g/kg body mass; 1.2 fat, 1.1 carbohydrate, 0.2 protein) on three occasions: after 3 d on a typical Western diet (46, 38 and 16 % energy from carbohydrate, fat and protein respectively); after 3 d on an isoenergetic high-carbohydrate diet (corresponding values: 70, 15 and 15 % energy); after 3 d on the same high-carbohydrate diet with 30 min moderate exercise daily. Fasting plasma TAG concentration was higher after the high-carbohydrate diet (1.15 (se 0.16) mmol/l) than after the Western diet (0.83 (se 0.10) mmol/l; ). Similarly, postprandial lipaemia (6 h total area under plasma TAG concentration v. time curve) was higher after the high-carbohydrate diet (12.54 (se 2.07) mmol/l.h) than after the Western diet (9.30 (se 1.30) mmol/l.h; ). The addition of exercise to the high-carbohydrate diet significantly reduced postprandial lipaemia (9.95 (se 1.94) mmol/l.h; when compared with the high-carbohydrate diet) but not fasting TAG concentration (1.02 (se 0.24) mmol/l). In conclusion, daily exercise prevented the augmentation of postprandial lipaemia attributable to the short-term high-carbohydrate diet and, thus, exercise may be a powerful adjunct to dietary change.