Timing of Meals and Exercise Affects Hormonal Control of Glucoregulation, Insulin Resistance, Substrate Metabolism, and Gastrointestinal Hormones, but Has Little Effect on Appetite in Postmenopausal Women.

Katarina T Borer,Po-Ju Lin,Elizabeth Wuorinen

doi:10.3390/nu13124342

Abstract

The current prevalence of obesity in the US is strongly associated with excessive food intake and insufficient physical activity. This study examined whether changing the timing of exercise before or after two daily meals could alter human appetite for food. Fifty-four healthy postmenopausal women were matched by body weight and assigned to two groups: (1) two bouts of 2-h moderate-intensity exercise ending one hour before each weight-maintenance meal (XM, n = 23), (2) two-hour moderate-intensity exercise starting 1 h after each weight-maintenance meal (MX, n = 23), and one sedentary control (SED) arm (n = 8). Measurements included appetite ratings, circulating glucose, free fatty acids (FFAs), a ketone body D-ß-hydroxybutyrate (BHB), glucoregulatory hormones insulin and glucagon, and gastrointestinal hormones associated with food digestion and absorption and implicated in appetite sensations. XM group increased concentrations of FFAs and BHB during exercise and increased insulin and homeostatic assessment of insulin resistance (HOMA-IR) during postprandial periods. MX group reduced postprandial insulin and HOMA-IR by about 50% without a major change in plasma glucose. There was brief suppression of hunger and an increase in satiation in both exercise groups near the end of the first postprandial period. The time course of hunger was unrelated to the perturbations in fuel metabolism, depletion of liver glycogen, and not correlated with concentration changes in hunger-stimulating hormone ghrelin during XM exercise before meals. Similarly, there was no correlation between the time course of fullness during exercise after meals with the postprandial secretion of gastrointestinal hormones including cholecystokinin (CCK) that has been linked to satiation. Hunger and satiation appear to depend on oral intake and gastrointestinal processing of nutrients and are not affected by metabolic and hormonal consequences of the timing of exercise with respect to meals. Moderate-intensity exercise performed shortly after meals induces a rapid and highly effective lowering of insulin resistance.

Highlights

The main finding was that the appetite and gastrointestinal physiology are largely independent of the increased metabolic effects of exercise performed in fasted state as well as of hormones of the gastrointestinal tract released during exercise in postprandial state
Appetite was unaffected by substantial increases in circulating metabolic fuels free fatty acids (FFAs) and body D-ß hydroxybutyrate (BHB) during exercise before the meals and by mealassociated increases in the hormones of the gastrointestinal tract that mediate digestion and absorption
We found no effect of meal-associated fluctuations in the putative satiation hormone CCK (Figures 13 and 14, right panels) and the visual analog scale (VAS) measure of fullness (Figure 9, lower right panel, Figure 10, right panel)

Summary

Introduction

It is important to understand physiological, hormonal, and metabolic influences on hunger and satiation linked to meal eating and physical activity to better provide effective solutions for weight management. In the US, the majority of residents engage in comparatively low levels of physical activity [1] and in excessive nutrient intake [2]. Meal eating and physical activity are intermittent human behaviors that are largely under voluntary control, and are responsive to body energy status. These two behaviors affect body energy balance in opposite ways. Our body weight and body fat reflect choices of what, when, how much we eat and our activity level

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Conclusion