The effects of exercise and ambient temperature on dietary intake, appetite sensation, and appetite regulating hormone concentrations

Abstract

Background It is not clear whether the frequently reported phenomenon of exercise-induced anorexia is exacerbated or blunted in warm or cold environments. Therefore, this study investigated the effects of exercise in three different environmental temperatures vs. rest, on perceptions of appetite, appetite regulating hormones, and food intake. Methods In a randomized repeated-measures design, 18 Canadian Armed Forces members (14 male, 4 female) completed four 8-h trials in a thermally-controlled chamber: one 8-h resting trial at 21 °C (Sedentary); and three trials where participants completed two 2-h circuits of standardized military tasks interspersed with two 2-h rest periods, once at 30 °C (Hot), once at 21 °C (Temperate), and once at − 10 °C (Cold). Participants consumed military field rations ad libitum and had their appetite assessed with visual analogue scales. Plasma concentrations of GLP-1, PYY, acylated ghrelin, and leptin were also determined. Results Appetite was perceived as being suppressed in the heat compared to the cold ( p < 0.05). While neither exercise nor environmental temperature altered circulating GLP-1 levels, exercise in all environments increased blood concentrations of PYY ( p < 0.05). Leptin concentrations were elevated in the heat and diminished in the cold (p < 0.05), and acylated ghrelin concentrations were affected by both exercise and ambient temperature resulting in Sedentary = Cold>Temperate = Hot ( p < 0.05). Contrary to the changes in appetite perceptions and hormonal concentrations, dietary intake was not different between conditions ( p > 0.05). Relative energy intake (total 24 h energy intake minus 24 h energy expenditure) on the other hand, was significantly higher during the Sedentary condition than it was during any of the active conditions (p < 0.05). Most (83%) of the participants were in a positive energy balance during the Sedentary condition, whereas during most (80%) of the active conditions (Hot, Temperate, Cold) participants were in a negative energy balance. Conclusions In this study where food was freely available, variations in ambient temperature, exercise vs. rest, appetite-regulating hormone concentrations, and subjective appetite sensation were not associated with any changes in dietary intake within 24-h of acute, prolonged exercise.

Hot, Tired and Hungry: The Snacking Behaviour and Food Cravings of Firefighters during Multi-Day Simulated Wildfire Suppression

“…Further, studies investigating food consumption after sleep restriction have not included physically demanding tasks and/or physical activity. In nonsleep restricted conditions, acute exercise does not influence immediate energy intake [37], but increased energy intake has been found 120 mins post-exercise, corresponding with increased ghrelin concentrations [65]. Current findings suggest this effect may be blunted with sleep restriction.…”

“…Taken together, these findings suggest that, in sleep restricted conditions, workers may self-select snacks high in carbohydrates, fat and sugar.Compared to cold temperature, food intake may be less following physically demanding tasks in hot temperatures [36]. For example, studies have found suppressed appetite in hot temperatures compared to cooler temperatures [37][38][39]. In one study, there was no difference between energy intake post-exercise between hot and neutral temperatures [40].…”

Comparison of dietary intakes of Canadian Armed Forces personnel consuming field rations in acute hot, cold, and temperate conditions with standardized infantry activities

“…Energy and macronutrient intakes were expressed per 24 h period to compare them to the 24 h energy expenditures. The present manuscript has a companion study that provides detailed methods and results on energy expenditure and appetite-related hormones [40].…”

“…An initial blood sample (10 ml) was taken from an antecubital vein (erythrocytes and plasma were separated within 1 h of collection), and then participants were provided with the breakfast meal from their self-selected ration packs. Blood samples were taken for the assessment of plasma concentrations of nutritional biomarkers (results provided in this manuscript) and appetite hormones (leptin, acylated ghrelin, GLP-1 and PPY) (for detailed analyses on appetite hormones, see Mandic et al [40]). The visual analogue scales for appetite (VASA) [43] were administered throughout the trial (for detailed analyses, see Mandic et al [40]).…”

ME3CA: A Cognitive Assistant for Physical Exercises that Monitors Emotions and the Environment

“…The Environmental Sensors allows the system to determine if the environmental signs are optimal for performing the exercises. They measure conditions such as temperature levels, humidity, CO2 and air quality among others, as high levels of these environmental factors can cause harmful effects when exercising [21][22][23].…”