Fasting increases serum total cholesterol, LDL cholesterol and apolipoprotein B in healthy, nonobese humans

Voluntary fasting is practiced by many humans in an attempt to lose body we ight, Conflicting results have been published on the effects of food depriv ation on serum lipids. To study the effect of acute starvation on serum lip ids, 10 nonobese (93-124% of ideal body weight), healthy adults (6 men, 4 w omen, 21-38 y old) fasted (90 energy) for 7 d. Fasting increased total seru m cholesterol from 4.90 +/- 0.23 to 6.73 +/- 0.41 mmol/L (37.3 +/- 5.0%; P < 0.0001) and LDL cholesterol from 2.95 +/- 0.21 to 4.90 +/- 0.36 mmol/L (6 6.1 +/- 6.6%; P < 0.0001), Serum apolipoprotein B (apo B) increased from 0. 84 +/- 0.06 to 1.37 +/- 0.11 g/L (65.0 +/- 9.2%; P < 0.0001), The increases in serum cholesterol, LDL and apo B were associated with weight loss. Fast ing did not affect serum concentrations of triacylglycerol and HDL choleste rol. Serum concentrations of insulin-like growth factor-I (IGF-I) decreased from 246 +/- 29 (prefast) to 87 +/- 10 mu g/L after 1 wk of fasting (P < 0 .0001). We conclude that, in nonobese subjects, fasting is accompanied by i ncreases in serum cholesterol, LDL and apo B concentrations, whereas IGF-I levels are decreased.