Understanding the mechanisms involved in exercise-induced appetite suppression

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Appetite regulation involves the integration of appetite-stimulating and appetite-inhibiting hormones in the hypothalamus. While eating is known to influence these hormones, the long-term objective of my NSERC research program is to understand how exercise affects these peripheral signals in humans. Using an integrative approach where exercise and nutrition are used to alter appetite regulation and study the effects of key peripheral appetite signals (i.e., acylated ghrelin, PYY, GLP-1), we are advancing understanding in the fields of energy intake regulation, metabolism, and nutrition. We have four short-term objectives that will be addressed over the next 5 years: 1)Clearly identify the role of lactate in appetite regulation 2)Explore the potential role of blood glucose and insulin in appetite regulation 3)Examine the potential role of the sympathetic nervous system (SNS) in appetite regulation 4)Elucidate any role of ovarian hormones in appetite-regulation We highlighted several potential mechanisms affecting these hormones such as blood flow, hypoxia, and inflammation (Hazell et al. 2016, Appetite). Our work derived from my initial NSERC Discovery Grant suggests appetite is suppressed after acute exercise in an intensity-dependent manner and this exercise-induced appetite suppression may be modulated by blood lactate accumulation. However, we cannot rule out the contributions of other exercise-related factors in appetite regulation such as blood glucose and insulin as there is strong animal work to support their role. We will also examine the role of the SNS, which is the most-hypothesized mechanism to be involved but with no data to support. Finally, we propose continuing our focus on role of ovarian hormones in appetite as females have been excluded from this type of research because hormonal fluctuations across the menstrual cycle have been viewed as an inconvenient confounding factor, rather than a relevant physiological modulator of appetite. The proposed work will be conducted in humans using serial blood draws (i.e., pre- and post-exercise) over several hours to establish a time course of effects. All sample sizes are based on detecting a significant difference in key appetite hormones established from previous work in males and females. Specific appetite-regulating hormones such as acylated ghrelin, PYY, GLP-1 and potential physiological mediators (lactate, glucose/insulin, SNS catecholamines, ovarian hormones) will be analyzed. All studies use acute exercise or nutrition (i.e., supplement) in unique study designs to further our understanding of the role of exercise in appetite regulation. IMPACT - It is important to explore and understand how exercise suppresses appetite. Improving our understanding appetite regulation is integral in the application of mechanistic research focused on how exercise can be structured to suppress appetite, and therefore improve body composition and overall health.