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 cross-over design, with 2 eight-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 17:00 and 21:00). Energy metabolism was evaluated at designated time points throughout the study by performing morning oral glucose tolerance tests (OGTT) and measuring levels of glucose, insulin, glucagon, leptin, ghrelin, adiponectin, resistin and brain-derived neurotrophic factor (BDNF). Subjects consuming 1 meal/d exhibited higher morning fasting plasma glucose levels, greater and more sustained elevations of plasma glucose concentrations and a delayed insulin response in the OGTT compared to subjects consuming 3 meal/d. Levels of ghrelin were elevated in response to the 1 meal/ d 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 to those consuming 3 meals/day. The impaired glucose tolerance was reversible and was not associated with alterations in the levels of adipokines or BDNF.

Metabolic impacts of altering meal frequency and timing – Does when we eat matter?

“…This study shows that limiting energy intake to late in the day is detrimental for metabolic health in humans, although no differences in insulinemia were noted [49]. It is unclear whether limiting the calorie allowance to the morning, or at lunch would have impacted this outcome.…”

“…Despite a small amount of weight loss, fasting blood glucose levels were increased, and TRF resulted in poorer glucose tolerance in response to an oral glucose tolerance test (OGTT) [49]. This study shows that limiting energy intake to late in the day is detrimental for metabolic health in humans, although no differences in insulinemia were noted [49].…”

“…To our knowledge, three randomised TRF intervention studies have been conducted in humans [28,49,88]. The first was a randomised controlled cross-over intervention, where lean individuals were instructed to consume all of their calories required for weight maintenance over a 4 h period from 17:00e21:00 h, or as 3 meals/ d for 8 weeks.…”

Meal frequency and timing in health and disease

“…Thus, far, relatively few RCTs of IER and TRF have been performed in human subjects, with the results of several studies of alternate-day and twice weekly energy restriction demonstrating weight loss and abdominal fat reduction and suggesting improvements in indicators of energy and lipid metabolism and inflammation (44-46, 51, 61). On the other hand, a study of TRF in which healthy normal weight subjects consumed a balanced daily food intake within a 4-h or 12-h time period each day revealed no improvement (79,80), which is similar to the lack of any short-term benefit of TRF in mice when the animals are fed a balanced diet (23). This finding suggests that the short-term benefits of TRF might depend on the diet and body composition.…”

Metabolic Effects of Intermittent Fasting

“…No biomarkers were assessed. Another crossover study reported a 4.1% weight loss effect of consuming a single meal in the afternoon each day for 8 weeks without calorie restriction compared with an isocaloric diet consumed as three meals per day (15,99). The one meal per day condition was also associated with reductions in fasting glucose and improvements in LDL and HDL cholesterol.…”