Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal-weight middle-aged men and women

Abstract

An unresolved issue in the field of diet and health is if and how changes in meal frequency affect energy metabolism in humans. We therefore evaluated the influence of reduced meal frequency without a reduction in energy intake on glucose metabolism in normal-weight, healthy male and female subjects. The study was a randomized crossover design, with two 8-week treatment periods (with an intervening 11-week off-diet period) in which subjects consumed all of their calories for weight maintenance distributed in either 3 meals or 1 meal per day (consumed between 4:00 pm and 8:00 pm). Energy metabolism was evaluated at designated time points throughout the study by performing morning oral glucose tolerance tests and measuring levels of glucose, insulin, glucagon, leptin, ghrelin, adiponectin, resistin, and brain-derived neurotrophic factor (BDNF). Subjects consuming 1 meal per day exhibited higher morning fasting plasma glucose levels, greater and more sustained elevations of plasma glucose concentrations, and a delayed insulin response in the oral glucose tolerance test compared with subjects consuming 3 meals per day. Levels of ghrelin were elevated in response to the 1-meal-per-day regimen. Fasting levels of insulin, leptin, ghrelin, adiponectin, resistin, and BDNF were not significantly affected by meal frequency. Subjects consuming a single large daily meal exhibit elevated fasting glucose levels and impaired morning glucose tolerance associated with a delayed insulin response during a 2-month diet period compared with those consuming 3 meals per day. The impaired glucose tolerance was reversible and was not associated with alterations in the levels of adipokines or BDNF.

Figure 1

Plasma glucose concentrations during the oral glucose tolerance tests during each study period. Data are presented as least squares means ± SEM, n = 15 (10 women, 5 men), from a repeated measures ANOVA. There was a significant treatment effect between the 1 meal/d (●) and the 3 meals/d (○) for the OGTT at 20 min, 40 min, 60 min and 80 min, ▲ P < 0.05.

Figure 2

Plasma insulin concentrations during the oral glucose tolerance tests during each study period. Data are presented as least squares means ± SEM, n = 15 (10 women, 5 men), from a repeated measures ANOVA. There was no significant treatment effect between the 1 meal/d (●) and the 3 meals/d (○) for plasma insulin concentrations during the oral glucose tolerance test.

Figure 3

Plasma ghrelin concentrations during the oral glucose tolerance tests during each study period. Data are presented as least squares means ± SEM, n = 15 (10 women, 5 men), from a repeated measures ANOVA. There was no significant treatment effect between the 1 meal/d (●) and the 3 meals/d (○) for plasma ghrelin concentrations during the oral glucose tolerance test.