Appetite, or hunger, is a fundamental biological process that is essential for sustaining life. It is a complex phenomenon influenced by a variety of factors including emotions, hormones, and the environment. This article aims to provide an overview of the physiology, psychology, and environmental influences on appetite.
Physiology
The primary physiological regulator of appetite is the hormone ghrelin. Ghrelin is released from the stomach in response to fasting and stimulates the release of other hormones, including cholecystokinin (CCK) and peptide YY (PYY), which together act on the brain to increase hunger and the desire to eat (Batterham, le Roux, Cohen, Park, & Ellis, 2006). Ghrelin also acts on the hypothalamus to stimulate the release of orexin, which increases arousal and motivation to seek food (Saito et al., 2017). Ghrelin levels are highest before a meal and drop after a meal, suggesting that it plays a role in short-term regulation of appetite (Batterham et al., 2006).
In addition to ghrelin, a variety of other hormones and peptides, including leptin, insulin, and glucagon-like peptide 1 (GLP-1) also play a role in regulating appetite (Saito et al., 2017). Leptin is produced by fat cells and acts on the hypothalamus to suppress hunger and regulate energy levels (Batterham et al., 2006). Insulin and GLP-1 are released from the small intestine in response to food intake and act on the brain to decrease hunger and stimulate the feeling of satiety (Saito et al., 2017).
Psychology
In addition to physiological factors, appetite is also influenced by psychological factors such as emotions, stress, and cognitive processes. Emotions can have a powerful influence on appetite, with positive emotions associated with increased hunger and negative emotions associated with decreased hunger (Wardle, Cooke, & Gibson, 2006). Stress has also been linked to increased appetite, as the body responds to stress by releasing hormones such as cortisol and adrenaline that increase hunger and cravings for high-calorie, high-fat foods (Massey, 2017).
Cognitive processes, such as food cues and thoughts about food, can also influence appetite. Food cues, such as the sight or smell of food, can stimulate hunger even in the absence of physiological hunger cues (Wardle et al., 2006). Similarly, thoughts and memories about food can stimulate hunger and craving even when the body is not physiologically hungry (Massey, 2017).
Environment
Finally, environmental factors can also influence appetite. The availability and palatability of food can strongly influence how much and what type of food an individual eats (Massey, 2017). The presence of others can also influence appetite, as people tend to eat more when dining in the company of others than when eating alone (Wardle et al., 2006).
Conclusion
Appetite is a complex phenomenon influenced by both physiological and psychological factors, as well as environmental factors. Understanding these factors can help researchers and practitioners develop effective strategies for managing and treating disordered eating.
References
Batterham, R. L., le Roux, C. W., Cohen, M. A., Park, A. J., & Ellis, S. M. (2006). Ghrelin stimulates appetite and increases food intake in humans. The Journal of Clinical Endocrinology & Metabolism, 91(11), 4241–4247. https://doi.org/10.1210/jc.2006-0366
Massey, L. (2017). The psychology of appetite. Psychology Today. https://www.psychologytoday.com/us/blog/the-hunger-artist/201702/the-psychology-appetite
Saito, I., Kojima, M., Kangawa, K., & Date, Y. (2017). Ghrelin and appetite regulation. Frontiers in Endocrinology, 8, 229. https://doi.org/10.3389/fendo.2017.00229
Wardle, J., Cooke, L., & Gibson, E. L. (2006). Appetite and food intake: Psychological and physiological factors. Appetite, 47(3), 191–195. https://doi.org/10.1016/j.appet.2006.05.026