Appetite is the desire to eat food and the portion consumed varies person to person depending upon need to ingest. It is regulated by a close interplay of singling pathways between the digestive tract, adipose tissues and the brain.
Exercise not only makes you fitter ,but is also believed to reduce your appetite and increase energy levels. So, it is an important component that can help manage body weight by regulating your appetite .
Firstly, exercise or physical activity ,creates an energy deficit or negative energy balance and aids weight loss.
Secondly, energy expenditure also influences the control of appetite through the physiological and psychological regulatory processes and ultimately energy intake. Certain studies have reviewed the effect of acute exercise, both aerobic and resistance exercise, on appetite in exercise-trained individuals and positive impact on appetite control.
Energy regulating hormones
1) Short term /Episodic signals / Gut Hormones -
Role :- regulate meal initiation and termination and determine frequency of meals and meal size.
Primary Hormones involved in appetite suppression
- Cholecystokinin (CCK) - inhibits gastric emptying
- Influences PYY release
- GLP-1 (Glucagon like peptide 1) - promotes insulin release , surpasses appetite
- PYY (Peptide tyrosine tyrosine) . - slows gastric emptying
Ghrelin , particularly is the main episodic signal to stimulate energy intake and increases gastric mobility.
2)Long term / Tonic signals -
Role :- More likely to regulate overall energy balance and body fat over days or weeks. As per studies , very high or low concentration of these circulating hormones have stimulating effect in food intake, whereas moderate levels have a suppressive effect.
Leptin and insulin are responsible for regulating these systems and have energy regulating properties that sense changes in energy balance and convey information to central processing centers (CNS) in the brain.
Leptin in particular is the major appetite suppressant and regulates energy metabolism. On the other hand, lowers blood sugar and stimulates glycogen synthesis.
Imbalance in hormones- Change in Energy status
Changes in energy status have a profound impact on the hormonal responses that modulate appetite. Any imbalance in regulation of hormones can be reflected in our changes in appetite, energy intake and expenditure.
Moreover, energy status may influence sensitivity to ghrelin (e.g., energy deficit = increased ghrelin sensitivity, energy surplus = ghrelin resistance).
How exercise can help regulate appetite?
Recent studies have shown that an acute exercise activity has the capacity to alter circulating appetite-regulating hormone concentrations. Further, exercise intensity may also influence the degree of appetite suppression. As HIE (High Intensity Exercise) has been shown to lead to greater appetite suppression than
low- or moderate-intensity exercise. especially in active sports women.
Although, more research is needed, examining the combined effect of diet and exercise on appetite regulation and control.
Moreover, exercise will influence all of these components that, in turn, will influence the drive to eat through the modulation of hunger (a conscious sensation reflecting a mental urge to eat) , also adjustments in postprandial satiety via an interaction with food composition. The individual responses to exercise will be highly variable and difficult to predict as it depends upon intensity and duration of workout , physical status and impact.
M Stephanie, et al (2014). Exercise-Trained Men and Women: Role of Exercise and Diet on Appetite and Energy Intake. Nutrients.ISSN 2072-6643
H. Todd.Physical Activity and Hormonal Regulation of Appetite: Sex Differences and Weight Control
Dorling et al (2018).Acute and Chronic Effects of Exercise on Appetite, Energy Intake, and Appetite-Related Hormones: The Modulating Effect of Adiposity, Sex, and Habitual Physical Activity.Nutrients 10, 1140; doi:10.3390/nu10091140.