Exercise prior to a freely requested meal modifies pre and postprandial glucose profile, substrate oxidation and sympathovagal balance

<p>Abstract</p> <p>Background</p> <p>The effects of exercise on glucose and metabolic events preceding and following a freely initiated meal have never been assessed. Moreover, the relationship between these events and sympathovagal balance is not known. The objective of this study was to determine whether exercise prior to a freely requested meal modifies the pre- and postprandial glucose profile, substrate oxidation and sympathovagal balance.</p> <p>Methods</p> <p>Nine young active male subjects consumed a standard breakfast (2298 ± 357 kJ). After 120 min, they either performed 75 min of exercise on a cycle ergometer (EX - 70% VO_2max) or rested (RT). Lunch was freely requested but eaten <it>ad libitum </it>only during the 1^stsession, and then energy intake was fixed across conditions. Glucose and sympathovagal balance were assessed continuously using a subcutaneous glucose monitoring system and analysis of heart rate variability, respectively. Every 5 min, a mean value was calculated for both glucose and sympathovagal balance. Substrate oxidation was determined by calculating the gas exchange ratio when lunch was requested and 180 min after the onset of eating.</p> <p>Results</p> <p>Preprandial glucose profiles were found in 72% of the sessions and with a similar frequency under both conditions. Meals were requested after a similar delay (40 ± 12 and 54 ± 10 min in EX and RT respectively; ns). At meal request, sympathovagal balance was not different between conditions but CHO oxidation was lower and fat oxidation higher in EX than in RT (-46% and +63%, respectively; both p < 0.05). Glucose responses to the meal were higher in incremental (+ 48%) but not in absolute value in EX than in RT, with a higher fat oxidation (+ 46%, p < 0.05), and a greater vagal withdrawal (+ 15%, p < 0.05).</p> <p>Conclusions</p> <p>These results show that exercise does not impair preprandial glucose declines at the following meal freely requested, but leads to an increased postprandial glucose response and an elevated fat oxidation, an effect that vagal withdrawal may contribute to explain.</p

Acute effects of pharmacological modifications of fatty acid metabolism on human satiety

The role of NEFA in eating behaviour is still poorly known. Our objective was to examine whether etomoxir (ETO), an inhibitor of NEFA oxidation, or (−)-hydroxycitrate (HCA), an inhibitor of lipogenesis which may indirectly stimulate NEFA oxidation, alters satiety. Post-lunch satiety was measured in eight normal-weight male subjects who were deprived of time cues and received on three occasions either ETO (320mg), HCA (2g) or placebo (PLA) in random order. Between lunch and dinner, blood was withdrawn continuously and collected every 10min for measures of plasma concentrations of glucose, insulin, lactate, TAG, NEFA, β-hydroxybutyrate (BHB), leptin and ghrelin. Results showed that HCA began to decrease hunger and desire to eat compared to PLA and ETO 210min after lunch and increased satiety duration compared to PLA by 70 (se 23) min (P<0·05), but did not modify energy intake at dinner. ETO did not affect any variable of satiety. HCA increased NEFA concentrations during the pre-dinner period, whereas ETO increased and decreased plasma concentrations of NEFA and BHB, respectively. Mean differences in plasma NEFA concentrations between HCA and PLA were predictive of the differences in satiety duration between treatments (r2 0·71, P<0·01). Among treatments, plasma leptin concentration at dinner onset was the only blood variable correlated with energy intake at this meal (r −0·75, P<0·0005). In healthy, normal-weight men, acute HCA increased the intensity and duration of satiety possibly via increased NEFA disposal for oxidatio

Physiology of energy homeostasis: Models, actors, challenges and the glucoadipostatic loop

International audienceThe aim of this review is to discuss the physiology of energy homeostasis (EH), which is a debated concept. Thus, we will see that the set-point theory is highly challenged and that other models integrating an anticipative component, such as energy allostasis, seem more relevant to experimental reports and life preservation. Moreover, the current obesity epidemic suggests that EH is poorly efficient in the modern human dietary environment. Non-homeostatic phenomena linked to hedonism and reward seem to profoundly impair EH. In this review, the apparent failed homeostatic responses to energy challenges such as exercise, cafeteria diet, overfeeding and diet-induced weight loss, as well as their putative determinants, are analyzed to highlight the mechanisms of EH. Then, the hormonal, neuronal, and metabolic factors of energy intake or energy expenditure are briefly presented. Last, this review focuses on the contributions of two of the most pivotal and often overlooked determinants of EH: the availability of endogenous energy and the pattern of energy intake. A glucoadipostatic loop model is finally proposed to link energy stored in adipose tissue to EH through changes in eating behavior via leptin and sympathetic nervous system activity

Energy compensation after an aerobic exercise session in high-fat/low-fit and low-fat/high-fit young male subjects

International audienceThere is general agreement that exercise-induced energy expenditure is not entirely compensated for at the next meal or over the following 24 h, but inter-individual variability is high. The role of ‘fatness and fitness’ in this variability has never been assessed. Therefore, eighteen non-obese male subjects aged 22·2 ( sd 2·0) years were selected and separated into a ‘high-fatness and low-fitness’ (Hfat/Lfit, n 9) and a ‘low-fatness and high-fitness’ (Lfat/Hfit, n 9) group, according to three criteria: maximal oxygen uptake; weekly hours of physical activity; fat mass index. At 1 h before lunch, they were subjected to 60 min of exercise on a cycle ergometer (70 % V O2max ), or stayed at rest. Then, they self-reported food intake in diaries until the next breakfast. Intake at lunch was not different between conditions, but was higher after exercise than after rest over the 24 h, leading to a significant but partial mean level of compensation of 49·8 ( sem 16·5) and 37·8 ( sem 24·6) % for the Hfat/Lfit and Lfat/Hfit groups, respectively. Energy compensation at lunch and over the 24 h were strongly correlated ( r 0·76, P < 0·001). Both groups consumed more fat and protein after exercise than after rest over the 24 h, but the percentage of energy derived from fat increased only in the Hfat/Lfit group (2·1 ( sem 0·6) %, P = 0·026). Thus, the energy cost of an aerobic exercise session was partially compensated over the next 24 h independently of the ‘fatness and fitness’ status, but ‘high-fat and low-fit’ individuals compensated more specifically on fats

Comparison of energy-matched high-intensity interval and moderate-intensity continuous exercise sessions on latency to eat, energy intake, and appetite

International audienceHigh-intensity interval exercises (HIIex) have gained popularity but their effects on eating behavior are poorly known. The aim of this study was to evaluate whether the effects of HIIex on the 3 main components of eating behavior (appetite, intake, and latency to eat) differ from those of moderate-intensity continuous exercises (MICex) for the same energy expenditure. Fifteen young normal-weight males completed 3 sessions in a counterbalanced order: HIIex(30-s bouts at 90% of maximal oxygen uptake interceded with 60-s bouts at 35% of maximal oxygen uptake for 20 min), MICex(42% of maximal oxygen uptake for 40 min), and a resting session (REST). Trials were scheduled 80 and 100 min after a standard breakfast for MICex and HII(ex,)respectively. At 120 min, participants were isolated until they asked for lunch. Appetite was rated on 4 visual analog scales (hunger, desire to eat, fullness, and prospective consumption) every 15 min until meal request. Results showed that the mean latency of requesting lunch was significantly longer after HIIex than after REST (+17.3 +/- 4.3 min, P= 0.004), but not after MICex (P = 0.686). Energy intake was not different between conditions, leading to a negative energy balance in the 2 exercise sessions. Thus, the effects of HIIex on eating behavior are likely primarily mediated through the latency of meal initiation. However, inter-individual variability was large and further studies are needed to identify the predictive factors of this response

Influence of environmental factors on meal intake in overweight and normal-weight male adolescents. A laboratory study

International audienceObjective: To investigate the influence of environmental conditions on energy intake at lunch time in normal-weight versus overweight male adolescents. Design: Healthy 15-17 year-old adolescents (19 normal-weight, 19 overweight) participated in lunch tests under laboratory settings. Four conditions were compared: eating in groups, eating alone, eating alone while viewing television, eating alone while listening to music. The same menus (two solid foods, three drinks) were offered ad libitum. Results: Significant group differences between meal conditions were observed for energy intake from solid foods, but not from drinks: normal-weight participants ate more solids while listening to music (5731 +/- 426 kJ) than when eating alone (5012 +/- 364 kJ, P = 0.026) or in groups (4974 +/- 272 kJ, P = 0.049). whereas overweight participants ate more solid foods while viewing television (5806 +/- 330 kJ) than when eating in groups (5208 +/- 201 kJ, P = 0.014) or while listening to music (5288 +/- 255 kJ, P = 0.035). On average, total energy intake at lunch (solids plus liquids) was found to be increased only in the overweight when viewing television (8527 +/- 535 kJ) compared to eating in group (7348 +/- 445 kJ, P = 0.037) or while listening to music (7532 +/- 435 kJ, P = 0.049). Conclusion: Environmental conditions modulate total energy intake at lunch in adolescents and susceptibility to external factors can be affected by weight status. Whether such effects can in turn affect energy balance and weight status remains to be investigated. (C) 2012 Elsevier Ltd. All rights reserved

Etude de l'oxydation des substrats, de la balance sympathovagale et du glucose pré et postprandial dans les relations entre exercice,hypoxie et comportement alimentaire

Exercice et hypoxie sollicitent l homéostasie énergétique dans lequel le système neuro-gluco-métabolique est fortement impliqué. Ces réponses ont rarement été étudiées lors d une séquence prandiale ou en relation avec le comportement alimentaire. Par ailleurs, le suivi en parallèle des cinétiques de ces réponses n a jamais été exploré. Cette thèse est composée de travaux consacrés à ces relations, conduits chez de jeunes sujets masculins en bonne santé, avec des techniques peu invasives permettant à la fois l expression d un comportement alimentaire spontané et une détermina-tion cinétique fine. Dans une première série de deux études, nous avons montré que ni l exercice physique ni l hypoxie précédant un repas demandé spontanément, ne modifiaient la séquence préprandiale (niveau de satiété, heure de la demande du repas et hypoglycémie préprandiale) mais que le repas était demandé avec un niveau d oxydation lipidique plus élevé.L exercice induisait une diminution de la tolérance relative au glucose, ainsi qu un retrait vagal plus important et une plus forte oxydation lipidique 3 h après le repas. Un entraînement de 6 semaines, réalisé soit à l état nourri, soit à jeun, ne modifiait pas ces réponses neuro-gluco-métaboliques. Dans une troisième étude, nous avons montré que la dépense énergétique d une séance d exercice n était que partiellement compensée au cours des 24 h, mais que chez des sujets ayant à la fois une faible condition physique et une adiposité relative élevée, cette compensation se faisait plus spécifiquement sur les lipides. Enfin, dans une quatrième étude, nous avons montré que la consommation d un repas hyperglucidique était en effet suivie d une plus faible désaturation artérielle en oxygène lors d un exercice pratiqué en hypoxie qu après celle d un repas hyperprotéique. Cette différence était accompagnée d une production de CO2 plus élevée et d une plus forte ventilation.Exercise and hypoxia exposure require energy homeostasis to operate, strongly involving the neuro-glucometabolic system. This response has rarely been studied during a prandial sequence and its relations with spontaneous eating behaviour has never been assessed. Moreover, the parallel recording of this response s kinetics has never been explored. This thesis consists in works about these relations that were conducted in healthy young male subjects, with non-invasive technics allowing subjects to display a spontaneous eating behaviour and an accurate assessment of variables kinetics. In a first serie of two studies, we showed that neither exercise nor hypoxia exposure prior to a spontaneously requested meal altered the prandial sequence (satiety level, delay of meal request, preprandial glucose decline) but that fat oxidation was greater when the meal was requested. Exercise induced a relative impaired glucose tolerance associated with a greater posprandial vagal withdrawal and a higher fat oxidation 3 h after the meal. Six weeks of training, conducted either in a fed or in a fasted state, did not change these neuro-gluco-metabolic postprandial profiles. In a third study, we showed that exercise-induced energy expenditure was weakly compensated for over the following 24 h, but that subjects with a low fitness condition and a relatively high body fatness, compensated more on dietary fats than high-fit, low-fat subjects. Lastly, in a fourth study, we showed that consuming a high-carbohydrate meal was followed by a lower arterial oxygen desaturation during an exercise session practiced in hypoxia, that consuming a high-protein meal. This difference was associated with a greater CO2 production and ventilation rate.PARIS13-BU Sciences (930792102) / SudocSudocFranceF

Daily energy balance and eating behaviour during a 14-day cold weather expedition in Greenland

International audienceWe assessed energy compensation, appetite, and reward value of foods during a 14-day military expedition in Greenland realized by 12 male French soldiers, during which energy compensation was optimized by providing them with easy-to-eat palatable foods in excess. Although daily energy expenditure (estimated by accelerometry) stayed relatively constant throughout the expedition (15 ± 9 MJ·day −1 ), energy intake (EI; estimated by self-reported diaries) was 17% higher during the D8–D14 period compared with the D1–D7 period, leading to a neutral energy balance (EB). Body fat mass (BFM) significantly decreased (–1.0 ± 0.7 kg, p < 0.001) but not body mass (BM). Neither hunger scores (assessed by visual analog scales) nor components of the reward value of food (explicit liking (EL) and food preference) were significantly altered. However, changes in EL at D10 were positively correlated with changes in BM (r = 0.600, p < 0.05) and BFM (r = 0.680, p < 0.05) and changes in hunger in the EI of the relevant period (r = 0.743, p < 0.01 for D1–D7, r = 0.652, p < 0.05 for D8–14). This study shows that the negative EB and BM loss can be attenuated by an appropriate food supply and that subjective components of eating behaviour, such as hunger and EL, may be useful to predict the magnitude of energy compensation. Novelty Energy intake increases during of a 14-day expedition in the cold. Energy compensation was likely facilitated by providing participants with easy-to-eat palatable and familiar foods. Hunger scores and EL for energy-dense foods were associated with high EIs and low BM changes