A High Energy Turnover Improves Appetite Control at Different Levels of Energy Balance

Abstract

Background: Weight control is hypothesized to be improved when physical activity and energy intake are both high (high energy turnover, ET). The impact of three levels of ET on appetite control is therefore investigated at fixed levels of energy balance. Methods: In a randomized controlled crossover trial, 16 healthy adults (25.1 ±3.9 y; BMI 24.0 ±3.2 kg/m2) spent 4 x 3 daylong protocols in a metabolic chamber. Energy requirement for different levels of energy turnover was measured at a baseline ad libitum intake condition. Four conditions of energy balance (ad libitum energy intake, zero energy balance, -25% caloric restriction and +25% overfeeding) were each performed at three levels of ET (low, medium and high ET, by walking on a treadmill). Levels of appetite hormones ghrelin, GLP-1 and insulin (tAUC) were measured over 14 hours. Subjective appetite ratings were assessed by Visual Analogue Scales. Results: Physical activity levels at low, medium and high ET were 1.3, 1.6 and 1.8 respectively. Compared to high ET, low ET led to decreased GLP-1 (at all energy balance conditions: p<0.001) and increased ghrelin levels (caloric restriction and overfeeding: p<0.001) which was consistent with higher feelings of hunger (zero energy balance: p<0.001) and desire to eat (all energy balance conditions: p<0.05) and a positive energy balance during ad libitum intake (+17.5%; p<0.001). Insulin levels were higher with low compared to high ET during overfeeding only (p<0.001). Conclusion: Appetite is regulated more effectively at a high level of energy turnover, whereas overeating and consequently weight gain is likely to occur at low levels of energy turnover. In contrast to the prevailing concept of body weight control, the positive impact of physical activity is independent from burning up more calories and is explained by improved appetite sensations.