Physiological responses to maximal eating in men

Abstract

This study investigated metabolic, endocrine, appetite and mood responses to a maximal eating occasion in fourteen men (mean: age 28 (sd 5) years, body mass 77·2 (sd 6·6) kg and BMI 24·2 (sd 2·2) kg/m2) who completed two trials in a randomised crossover design. On each occasion, participants ate a homogenous mixed-macronutrient meal (pizza). On one occasion, they ate until ‘comfortably full’ (ad libitum) and on the other, until they ‘could not eat another bite’ (maximal). Mean energy intake was double in the maximal (13 024 (95 % CI 10 964, 15 084) kJ; 3113 (95 % CI 2620, 3605) kcal) compared with the ad libitum trial (6627 (95 % CI 5708, 7547) kJ; 1584 (95 % CI 1364, 1804) kcal). Serum insulin incremental AUC (iAUC) increased approximately 1·5-fold in the maximal compared with ad libitum trial (mean: ad libitum 43·8 (95 % CI 28·3, 59·3) nmol/l × 240 min and maximal 67·7 (95 % CI 47·0, 88·5) nmol/l × 240 min, P < 0·01), but glucose iAUC did not differ between trials (ad libitum 94·3 (95 % CI 30·3, 158·2) mmol/l × 240 min and maximal 126·5 (95 % CI 76·9, 176·0) mmol/l × 240 min, P = 0·19). TAG iAUC was approximately 1·5-fold greater in the maximal v. ad libitum trial (ad libitum 98·6 (95 % CI 69·9, 127·2) mmol/l × 240 min and maximal 146·4 (95 % CI 88·6, 204·1) mmol/l × 240 min, P < 0·01). Total glucagon-like peptide-1, glucose-dependent insulinotropic peptide and peptide tyrosine–tyrosine iAUC were greater in the maximal compared with ad libitum trial (P < 0·05). Total ghrelin concentrations decreased to a similar extent, but AUC was slightly lower in the maximal v. ad libitum trial (P = 0·02). There were marked differences on appetite and mood between trials, most notably maximal eating caused a prolonged increase in lethargy. Healthy men have the capacity to eat twice the energy content required to achieve comfortable fullness at a single meal. Postprandial glycaemia is well regulated following initial overeating, with elevated postprandial insulinaemia probably contributing.

Human and mouse muscle transcriptomic analyses identify insulin receptor mRNA downregulation in hyperinsulinemia‐associated insulin resistance

“…Circulating insulin in humans oscillates in a range between approximately 0.01 and 0.75 nM 35,42–46 . Although there is no standard criteria for hyperinsulinemia, fasting insulin higher than 0.085 nM is considered to be associated with insulin resistance 43 .…”

“…Circulating insulin in humans oscillates in a range between approximately 0.01 and 0.75 nM. 35,[42][43][44][45][46] Although there is no standard criteria for hyperinsulinemia, fasting insulin higher than 0.085 nM is considered to be associated with insulin resistance. 43 As for mice, fed insulin is ~0.2 nM in lean mice and ~3-5 nM in extremely obese mice such as the Lep ob/ob strain.…”

A randomized controlled trial to isolate the effects of fasting and energy restriction on weight loss and metabolic health in lean adults

“…It is also conceivable that systematic bradycardia or tachycardia may respectively explain the lower energy expenditure with fasting or the higher energy expenditure when refeeding (particularly considering the increase in physical activity specific to fed periods in the group who avoided energy restriction). This is also unlikely, however, because extreme (even maximal) overeating only increases resting heart rate by ~6 beats min −1 in the immediate postprandial period (37) and by ~2 beats min −1 after a week of energy surplus (38). Recent work has also now reported anticipatory behavioral modification even outside the period of dietary intervention, which cannot, therefore, be attributed to changes in heart rate during the fast (39).…”

The physiology of experimental overfeeding in animals

“…If calorie consumption is ‘clamped’ at a sufficiently high level, the intervention elicits a rapid increase in body weight and fatness and a potent suppression of appetite that counteracts the positive energy balance generated by the overfeeding intervention ( Figure 2 ). Experimental overfeeding interventions in humans are sometimes referred to as ‘voluntary overfeeding’ or ‘conscious overfeeding’ [ 14 , 15 ] and the overfeeding interventions range from a single high-caloric meal [ 16 ] to a sustained excess caloric intake for several months [ 17 ]. The energetic surplus typically ranges from 30 to 50% over baseline caloric intake, corresponding to ingesting 130–150% of the energy needed for body weight stability [ 18 ].…”