Increased low density lipoprotein production associated with obesity.

Turnover rates of the apolipoprotein of low density lipoproteins (apoLDL) and cholesterol balance were determined in six obese men and six control men. The two groups were of similar age and matched for apoLDL concentrations. Levels of plasma total cholesterol in obese patients (209 +/- 14 SEM mg/dl) were similar to controls (225 +/- 17 mg/dl). LDL-cholesterol was numerically but not statistically lower in obese subjects (111 +/- 18 mg/dl) compared to controls (145 +/- 13 mg/dl). Synthetic rates of apoLDL in contrast were higher in obese patients (1450 mg/day) than in controls (934 mg/day) (p less than 0.002). Three factors could explain the similar concentrations of LDL-cholesterol in obese and control subjects, despite overproduction of apoLDL in the obese. First, LDL was diluted into a larger plasma pool in obese patients; second, fractional catabolic rates of apoLDL were somewhat greater in obese men than in controls; and third, obese patients had higher ratios of protein-to-cholesterol in LDL. The production of apoLDL for all patients was not correlated with total body synthesis of cholesterol. The major finding of this study was that obese patients have increased turnover of apoLDL, not necessarily reflected by high concentrations of LDL-cholesterol. This high turnover rate itself may raise the risk for coronary heart disease in obese patients.