The effect of diurnal distribution of carbohydrates and fat on glycaemic control in humans: a randomized controlled trial

Abstract

Diurnal carbohydrate and fat distribution modulates glycaemic control in rodents. In humans, the optimal timing of both macronutrients and its effects on glycaemic control after prolonged consumption are not studied in detail. In this cross-over trial, 29 non-obese men were randomized to two four-week diets: (1) carbohydrate-rich meals until 13.30 and fat-rich meals between 16.30 and 22.00 (HC/HF) versus (2) inverse sequence of meals (HF/HC). After each trial period two meal tolerance tests were performed, at 09.00 and 15.40, respectively, according to the previous intervention. On the HF/HC diet, whole-day glucose level was increased by 7.9% (p = 0.026) in subjects with impaired fasting glucose and/or impaired glucose tolerance (IFG/IGT, n = 11), and GLP-1 by 10.2% (p = 0.041) in normal glucose-tolerant subjects (NGT, n = 18). Diet effects on fasting GLP-1 (p = 0.009) and PYY (p = 0.034) levels were observed in IFG/IGT, but not in NGT. Afternoon decline of glucose tolerance was more pronounced in IFG/IGT and associated with a stronger decrease of postprandial GLP-1 and PYY levels, but not with changes of cortisol rhythm. In conclusion, the HF/HC diet shows an unfavourable effect on glycaemic control in IFG/IGT, but not in NGT subjects. Consequently, large, carbohydrate-rich dinners should be avoided, primarily by subjects with impaired glucose metabolism.

High Glycemic Index Metabolic Damage – a Pivotal Role of GIP and GLP-1

“…Postprandial increases in glucose differ dramatically between individuals, even to similar foods [11], and are determined not only by the speed and quantity of insulin and glucagon secretion, but also by an array of variables including body composition, age, microbiome, fiber intake, and circadian changes in insulin sensitivity [11][12][13].…”

“…In addition to the speed of digestion and absorption of a specific carbohydrate, the kinetics and quantity of insulin secretion, the inhibition of glucagon release, and gastric emptying directly determine postprandial glucose levels [3,4,7,8,11,12]. Moreover, GI is highly circadian and increases in blood glucose for similar meals are two to three times greater in the evening as compared to the morning [13]. lipogenic and trophic metabolic signals.…”

Saliva Samples as A Tool to Study the Effect of Meal Timing on Metabolic And Inflammatory Biomarkers

“…Epidemiological studies in humans show that increasing carbohydrate intake at breakfast while simultaneously reducing fat intake seems protective against the development of diabetes and metabolic syndrome [9,10]. Similarly, we recently showed that a diet in which fat is mainly eaten in the morning and carbohydrates mainly in the evening (compared with the reverse order) worsens glycaemic control in people with prediabetes [11] and alters substrate oxidation and adipokine secretion [12]. These studies indicate that timing of carbohydrates and fat in an important factor influencing metabolic health.…”

“…The study was registered at clinicaltrials.gov as NCT02487576. Details of the study design, the recruitment of participants, inclusion and exclusion criteria, and dietary interventions were published elsewhere [11,12].…”

“…For each participant, individual isocaloric dietary plans were designed. These plans met the target macronutrient composition of both diets and considered individual food preferences which were obtained from food records handed out prior to trial commencement [11,12]. Participants were asked to daily document their food selection, consumed amount and time of each meal ( Figure S1).…”