Delayed postprandial metabolism of triglyceride-rich lipoproteins in obese young men compared to lean young men

BackgroundObesity, especially visceral obesity, has been known to affect lipoprotein metabolism, but it is not clear whether obesity in young, apparently healthy men is associated with postprandial triglyceride-rich lipoprotein (TRL) metabolism.MethodsTen young normolipidemic, normoglycemic obese men (20.6 ± 0.5 y, BMI 27.5 ± 1.0 kg/m2) and 11 lean healthy men (22.1 ± 0.4 y, 21.2 ± 0.4 kg/m2) ingested OFTT cream (1 g/kg body weight). Fasting and postprandial blood samples were obtained for up to 6 h, and serum lipids and lipoproteins were analyzed.ResultsThe obese men with a fasting triglyceride (TG) in the normal range and not different from the fasting value of lean controls had a prolonged postprandial response, indicated by a significantly greater incremental areas under the curve in serum TG, TRL-TG, and remnant-like particle-cholesterol (RLP-C) compared with controls. Plasma glucose levels did not change during the test. Differences in serum insulin levels and homeostasis model assessment-insulin resistance (HOMA-IR) were not statistically significant between the two groups; however, trends toward higher levels were shown in obese young men.ConclusionsThe obese young men showed significantly delayed TRL metabolism compared to the lean young men after fat loading, even though the obese men were normolipidemic. These results suggest the possibility that early insulin resistance in the obese young men may have caused the decrease of lipoprotein lipase activity and induced delayed TRL metabolism. A fat loading test without carbohydrate may provide a useful tool for the detection of delayed postprandial TRL metabolism and early insulin resistance.