Genotype-influenced changes in serum HDL cholesterol after short-term overfeeding in man: Association with plasma insulin and triglyceride levels

Six pairs of male monozygotic (MZ) twins were submitted to a 22-day overfeeding period during which they ingested a daily surplus of 1,000 kcal above their individual daily energy needs in the form of a mixed diet. Serum lipids, lipoproteins, and apoprotein A and B concentrations were measured before and after the overfeeding period. Percentage of body fat, fasting plasma glucose, and insulin levels as well as plasma glucose and insulin concentrations after a glucose challenge were also measured before and after overfeeding. Results showed that before overfeeding, MZ twins exhibited a significant intrapair resemblance for total serum cholesterol (CHOL), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), and for the high density lipoprotein-cholesterol/total cholesterol ratio ( HDL-C CHOL ) (8.2 ≦ F ratios ≦ 32.7, P < .01). The overfeeding experiment induced significant increases only in serum CHOL (P < .01) and in serum LDL-C (P < .05). However, although mean group values of serum TG, HDL-C, and HDL-C CHOL ratio were not significantly modified by overfeeding, there were large interindividual variations in the response of these variables to the experiment. Results suggest that changes in serum TG, HDL-C, and in the HDL-C CHOL ratio were significantly associated with the genotype of the subjects as a significant intrapair resemblance in the response to overfeeding was observed for these variables (0.69 ≦ r ≦ .85, P < .05). Moreover, individual changes in serum HDL-C and in HDL-C CHOL ratio were negatively correlated with changes in serum TG (r = −.64, P < .05 and r = −.84, P < .01; respectively). Finally, subjects that showed an increase in serum TG levels during overfeeding also demonstrated elevated fasting plasma insulin concentrations (r = .67, P < .05) and increased plasma insulin levels during an oral glucose challenge (r = .68; P < .05). These results suggest that the genotype may determine the sensitivity to develop hypertriglyceridemia and a potentially atherogenic lipoprotein-lipid profile (reduced HDL-C CHOL ratio) following a short-term caloric excess. These results also suggest that heredity plays a role in the interindividual variation observed in plasma lipoproteins when chronically overfed.