Homeostatic and neurocognitive control of energy intake in response to exercise in pediatric obesity: a psychobiological framework

While energy intake and energy expenditure have long been studied independently, the alarming progression of obesity has led to a more integrative approach to energy balance considering their potential interactions. Although the available literature concerned with the effect of chronic and acute exercise on energy intake and appetite control in adults is considerable, these questions remain less explored among children and adolescents. Based on the search of four databases (Medline, Embase, PsycINFO and Cochrane Library; articles published until May 2018), the objective of this review is to summarize and discuss the effect of acute and chronic physical exercise on energy intake and appetite control in children and adolescents with obesity, and to identify the physiological and neurocognitive signals and pathways involved. Evidence suggested that acute intensive exercise has the potential to reduce subsequent energy intake in children and adolescents with obesity but not healthy weight, through both peripheral (mainly gastro-peptides) and neurocognitive (neural responses to food cues) pathways. The nutritional responses to chronic physical activity remain less clear and require further consideration, especially from an anti-obesity perspective.

The life history of whole-organism performance

For almost 40 years, studies of whole-organism performance have formed a cornerstone of evolutionary physiology. Although its utility as a heuristic guide is beyond question, and we have learned much about morphological evolution from its application, the ecomorphological paradigm has frequently been applied to performance evolution in ways that range from unsatisfactory to inappropriate. More importantly, the standard ecomorphological paradigm does not account for tradeoffs among performance and other traits, nor between performance traits that are mediated by resource allocation. A revised paradigm that includes such tradeoffs, and the possible ways that performance and fitness-enhancing traits might affect each other, could potentially revivify the study of phenotypic evolution and make important inroads into understanding the relationships between morphology and performance and between performance and Darwinian fitness. We describe such a paradigm, and discuss the various ways that performance and key life-history traits might interact with and affect each other. We emphasize both the proximate mechanisms potentially linking such traits, and the likely ultimate factors driving those linkages, as well as the evolutionary implications for the overall, multivariate phenotype. Finally, we highlight several research directions that will shed light on the evolution and ecology of whole-organism performance and related life-history traits.

Nutritional responses to acute training sessions in young elite rugby players

BACKGROUND

Acute exercise has been shown to induce nutritional adaptations in obese and lean inactive youth but it remains unclear whether youth with a high level of physical activity experience such exercise-induced energy intake and appetite modifications.

METHODS

14 (15- to 16-year-old) male elite rugby players completed sessions on three separate occasions: (1) a control session (CON); (2) an exercise session (EX) and; (3) a rugby session (RUGBY). The energy induced by the rugby and exercise sessions was matched (Polar Team2 pro technology), and participants' energy intake, food preferences (ad libitum buffet meals) and appetite feelings (Visual Analogue Scales) were assessed throughout the experimental days.

RESULTS

The energy intake during lunch and snack time was not different between conditions. Dinner time energy intake was significantly increased after RUBGY compared to CON with respectively 969 ± 145 kcal and 777 ± 183 kcal (p < 0.05). The energy intake at dinner time was significantly increased during EX (1185 ± 199 kcal) compared to both CON (p < 0.001) and RUGBY (p < 0.01). None of the appetite feelings investigated were modified between sessions.

CONCLUSION

Adolescent elite rugby players regulate their energy intake differently depending on the nature of their training; independently of the energy expended. This demonstrates the need for energetic and nutritional education to optimize their physical fitness and performance.

Plasma acylated ghrelin response to one session circuit resistance exercise in fasted and high carbohydrate meal in healthy young men

BACKGROUND

Ghrelin, a 28 amino acid peptide, is effective in control of appetite and body weight. Acylated ghrelin peptide is the active form of this peptide which plays a major role in the body's energy balance.

OBJECTIVES

This study aimed to investigate the possible effect (s) of intensive resistance exercise on acylated ghrelin, growth hormone, glucose, insulin, and cortisol plasma levels.

PATIENTS AND METHODS

Forty male students with the mean age of 19.22 ± 0.26 years and BMI 21.02 ± 0.33 (kg/m(2)) were randomly divided into experimental and control groups. Experimental group performed a single session of circuit resistance exercise with 80% 1RM in both fasting and high carbohydrate meal. Blood samples were collected before and immediately after exercise to measure the concentrations of mentioned variables.

RESULTS

Two-way ANOVA showed that acylated ghrelin and fasting plasma glucose levels after exercise in both high-carbohydrate and fasting groups were significantly increased compared to the control group (P < 0.05), but the levels of insulin, cortisol, and growth hormones did not have any significant change.

CONCLUSIONS

Totally, it seems that the increased plasma acylated ghrelin during exercise is due to the decrease of muscle and liver energy stores which provides conditions for increased energy intake and positive energy balance.

Influence of netball-based exercise on energy intake, subjective appetite and plasma acylated ghrelin in adolescent girls

This study explored 5-day regulation of exercise-induced energy expenditure, energy intake, and hormonal appetite, via acylated ghrelin, after acute exercise. Using a randomized crossover design, 10 female adolescents (13-15 years old) completed two 7-day treatment weeks (2 days of maintenance, 1 day of treatment, and a 4-day follow-up), interspersed with a 1-week period. On day 3, 47 min of netball-based exercise or sedentary activity was imposed with a test meal 1 h later. Measures of energy expenditure, subjective appetite, test meal energy intake, plasma acylated ghrelin, insulin, and glucose were taken during this period. Energy intake compensation for the exercise period was calculated. Four-day follow-up measures were daily subjective appetite, energy intake, energy expenditure, and energy balance. Girls felt more full 20 min during the netball-based exercise bout compared with sedentary activity (87 ± 15 mm vs. 75 ± 24 mm). An energy intake compensation of 27% was identified for the netball-based exercise. Compared with immediately before exercise or sedentary activity, plasma acylated ghrelin was elevated 45 min after netball (103.8 ± 56.9 pg·mL(-1) vs. 85.7 ± 26.9 pg·mL(-1); n = 7) and sedentary activity (98.2 ± 27.1 pg·mL(-1) vs. 60.8 ± 33.5 pg·mL(-1); n = 7) but not different between treatments. Adolescent girls (13-15 years old) only partially compensated for the netball-based exercise-induced energy expenditure. The effect of exercise on appetite needs to be further explored in adolescents, whereby nutritional behaviour is tracked for more than 1 week to investigate full compensation for acute exercise.

Daily energy balance in children and adolescents. Does energy expenditure predict subsequent energy intake?

Both physical and sedentary activities primarily impact energy balance through energy expenditure, but they also have important implications in term of ingestive behavior. The literature provides scarce evidence on the relationship between daily activities and subsequent nutritional adaptations in children and adolescents. Sedentary activities and physical exercise are generally considered distinctly despite the fact that they represent the whole continuum of daily activity-induced energy expenditure. This brief review paper examines the impact of daily activities (from vigorous physical activity to imposed sedentary behaviors) on acute energy intake control of lean and obese children and adolescents, and whether energy expenditure is the main predictor of subsequent energy intake in this population. After an overview of the available literature, we conclude that both acute physical activity and sedentary behaviors induce food consumption modifications in children and adolescents but also that the important discrepancy between the methodologies used does not allow any clear conclusion so far. When considering energy intake responses according to the level of energy expenditure generated by those activities, it is clear that energy expenditure is not the main predictor of food consumption in both lean and obese children and adolescents. This suggests that other characteristics of those activities may have a greater impact on calorie intake (such as intensity, duration or induced mental stress) and that energy intake may be mainly determined by non-homeostatic pathways that could override the energetic and hormonal signals.