Hormonal Imbalance and Eating Disorders
Hormones are chemical substances in our body that regulate several processes, such as food intake, hunger and satiety. Several hormones found in the gut, such as ghrelin, cholecystokinin (CCK) and leptin, influence the rate of gastric emptying, trigger feelings of hunger, and control how much food you eat until you are full. Too much or too little of a specific hormone can lead to several complications.
Current research suggests that eating disorders are characterized by altered levels of hunger and satiety hormones. These hormonal imbalances have been used to explain the restrictive behaviour in anorexia, and the ‘binge’ episodes in bulimia and binge eating disorder. However, it is controversial whether hormonal dysregulation precedes the onset of the eating disorder, or occurs as a result of the disordered eating behaviour.
Ghrelin is secreted by gastro-intestinal cells when the stomach is empty, and stops being secreted when the stomach is stretched. Therefore, it signals hunger to the brain and it is elevated before meals, triggering the onset of eating. Studies have found that ghrelin does not reduce normally after a meal in bulimia nervosa. This means less satiety and less reduction in hunger after eating. The same hormonal imbalance is also seen in people with binge eating disorder. This could explain the ‘binge’ cycle seen in these disorders, and the reduction of the experience of satiety, hence eating bigger amounts of food to feel full.
Leptin is a satiety hormone produced by fat cells. Leptin levels are correlated with fat mass and body weight. Therefore, extreme weight loss leads to reduced levels of the leptin hormone, subsequently increasing appetite. People with anorexia nervosa due to extreme low body weight have fewer fat cells, and so they have less leptin. Although, they are not eating more because of the fear of weight gain and body image distress, they think and obsess a lot over food, and this can be related to low leptin levels.
CCK is a hormone produced in the gut and the brain. It reduces both hunger, appetite and gastric emptying. After a meal, individuals with active and remitted bulimia nervosa show less reduction of CCK compared to healthy people. This could account for some of the behavioral aspects of the disorder, such as restricting and feeling hungry all the time leading to a loss of control over eating during a binge episode.
Is hormonal imbalance reversible with eating disorder treatment?
A combination of dietary and psychological intervention has the potential to improve hormonal imbalance in people with eating disorders. However, hunger-satiety is a very complex interactive system, and further research is needed to understand how different hormones might precipitate the behavioral aspects of eating disorders.
Source: Prince, A.C., Brooks, S.J., Stahl, D. and Treasure, J. (2009) Systematic review and meta-analysis of the baseline concentrations and physiologic responses of gut hormones to food in eating disorders, American Journal of Clinical Nutrition, 89(3), pp. 755–765