EFFECT OF DIETARY MACRONUTRIENT COMPOSITION ON TISSUE-SPECIFIC LIPOPROTEIN-LIPASE ACTIVITY AND INSULIN ACTION IN NORMAL-WEIGHT SUBJECTS

The effects of macronutrient composition on fasting and postprandial a ctivities of adipose tissue lipoprotein lipase (ATLPL) and skeletal mu scle LPL (SMLPL) and on insulin sensitivity (S-I) were studied in 25 n ormal-weight subjects, Each subject was fed a high-carbohydrate (HC) d iet for 16 d and a high-fat (HF) diet for 16 d, in randomized order, O n day 15 of each diet, biopsies for ATLPL and SMLPL were done in the f asted state and 6 h postprandially. On day 16 of each diet, a euglycem ic clamp was used to measure S-I. There was no effect of diet composit ion on fasting ATLPL or SMLPL. With both diets and in both tissues. LP L increased significantly from fasting to 6 h postprandially. In adipo se tissue only there was a significant difference between the 2 diets in LPL meal response (HC > HF, P = 0.024). There was no effect of diet composition on S-I. After the HC diet only, then were significant cor relations between fasting SMLPL and S-I, but not ATLPL. After the I-IF diet, associations between insulin action and LPL were evident only i n the postprandial state. In summary, 16 d of HC compared with HF feed ing in normal-weight subjects increased the responsiveness of ATLPL to an HC compared with an HF meal, However, the same diets had no effect on fasting ATLPL or SMLPL, the responsiveness of SMLPL to a meal. or S-I. These data suggest that in normal-weight subjects habitual dietar y carbohydrate intake may have a stronger effect on Subcutaneous fat s torage than does dietary fat intake.