Meal frequency influences circulating hormone levels but not lipogenesis rates in humans

To determine whether human lipogenesis is influenced by the frequency of meal consumption, 12 subjects were divided into two groups and fed isocaloric nutritionally adequate liquid diets over 3 days, either as three larger diurnal (n = 6) or as six small, evenly spaced (n = 6) meals per day. On day 2 (08:00 h) of each diet period, 0.7 g deuterium (D) oxide/kg body water was administered and blood was collected every 4 hours over 48 hours for measurement of plasma insulin and glucose-dependent insulinotropic polypeptide (GIP) levels. At each time point, the incorporation of D into plasma triglyceride fatty acid (TG-FA) was also determined by isotope ratio mass spectrometry after TG-FA extraction and combustion/reduction. Insulin and GIP levels were elevated over daytime periods in subjects fed three versus six meals per day. Contribution of de novo synthesis to total TG-FA production was not significantly different for days 2 and 3 in subjects consuming three (6.56% +/- 1.32% and 6.64% +/- 2.08%, respectively) and six (7.67% +/- 2.29% and 7.88% +/- 1.46%, respectively) meals per day. Net TG-FA synthesis rates over days 2 and 3 were 1.47 +/- 0.33 and 1.55 +/- 0.53 g/d, respectively, for subjects fed three meals per day, and 1.64 +/- 0.47 and 1.69 +/- 0.30 g/d for subjects fed six meals per day. These findings suggest that consuming fewer but larger daily meals is not accompanied by increases in TG-FA synthesis, despite the observation of hormonal peaks.