An eating disorder is where a person has an abnormal eating behaviour which significantly affects their physical and psychological wellbeing. There might be an intense focus on weight, body image, and eating habits, and there may be social and cultural factors that play a role as well. Eating disorders include anorexia nervosa, bulimia nervosa, binge-eating disorder, avoidant restrictive food intake disorder (ARFID), other specified feeding or eating disorder (OFSED).
In anorexia nervosa people are very underweight as a result of extreme dieting or excessive exercise. People with bulimia nervosa have a ‘normal weight’, higher than average weight or obesity but they have cycles of uncontrollable overeating. During this time, they consume large quantities of food while feeling out of control and powerless to stop (bingeing), followed by making themselves sick after meals or abusing laxatives (purging) to make up for the food eaten. In contrast, people with a binge-eating disorder have frequent episodes of uncontrollable binge eating but do not attempt to make up for the binges through vomiting, fasting, or over-exercising. As a result, people with a binge-eating disorder often have obesity.
In avoidant restrictive food intake disorder, also known as ARFID, a person avoids eating certain foods or types of foods because of increased sensitivity, concerns of consequences of eating or low interest in eating and are more likely to lose weight. Pica is a condition where a person persistently eats non-food substances that have no nutritional value such as dirt, hair, paint, paper, and other items. In rumination syndrome, the individual repeatedly and effortlessly brings up recently eaten food without feeling sick which they then spit out or re-swallow. If an individual does not fit the expected symptoms of anorexia, bulimia or binge-eating disorder, they might be diagnosed with other specific feeding or eating disorder (OFSED). There is a higher risk of developing an eating disorder with certain chronic medical conditions such as in Type 1 and Disordered Eating (T1DE).
Our eating habits and weight have an important relationship with our hormones. In turn, hormones influence our overall growth and development, bone growth, puberty, fertility, level of alertness, sugar regulation and appetite. In eating disorders, the effects of unhealthy eating patterns can influence hormone levels, causing physical and psychological problems.
Metabolism refers to the set of chemical reactions which happens within the body that allows us to grow, maintain energy levels and respond to the environment around us. Several hormones are involved in regulating the body’s metabolism, many of which are affected by eating disorders. These hormonal changes are an appropriate response to starvation and will serve to save energy.
When an eating disorder starts in early years, it can alter the hormones involved in puberty and growth. Puberty may be delayed and bones may fail to grow, leading to reduced growth and brittle bones (osteoporosis) later in life.
Eating disorders can also lead to low levels of thyroid hormones (hypothyroidism) and people with this condition may feel cold and complain of constipation or dry skin.
Eating disorders can stimulate the production of the so-called ‘stress hormones’, which include cortisol, growth hormone and noradrenaline. These hormones are usually released in higher concentrations at periods of high stress and can lead to sleep problems, feelings of anxiety, depression and panic. Similarly, there is a strong physical response including an increase in heart rate, rate of breathing and/or blood pressure.
Eating disorders mainly affect young people at what would otherwise be the peak of their reproductive lives. Unhealthy eating styles can lead to changes in reproductive hormones that are responsible for maintaining regular periods, sex drive, healthy hearts and strong bones. As a result, some women will have irregular periods, some will stop having them altogether and some may suffer infertility. Men, on the other hand, may lose their sex drive or have erectile problems. This is, again, the body’s response to trying to save energy and prevent reproduction in a starving individual. Hormones often return to normal levels when the amount of food being eaten increases (in cases where too little food has been consumed for a period of time), or when a significant amount of weight is lost (in cases where the eating disorder has led to obesity).
In the few cases where pregnancy does occur, eating disorders also have an impact on reproductive hormones during pregnancy, affecting both the mother and baby. Some studies suggest that women with eating disorders are at higher risk of complications around the time of pregnancy, including the need for a caesarean section, postnatal depression, miscarriage, complicated delivery and premature birth. However, most pregnant women who have recovered from eating disorders have healthy pregnancies.
In binge-eating disorder, compulsive overeating often leads to obesity. Obesity, in turn, increases the risk of developing medical conditions such as high cholesterol levels, diabetes, heart disease, gallstones, liver disease, osteoarthritis, gout and certain types of cancer. Obesity also causes an increase in hormone levels that encourages the build-up of body fat, thus making it even harder to lose weight. Treatment is focused on psychological change (for example, addressing the emotional reasons that lead to overeating) as well as behavioural changes, such as healthy eating and regular exercise. In some cases, medication and/or surgery may be required to produce significant and/or long-lasting weight loss.
Eating disorders can have serious physical and psychological consequences, many of which are caused by changes in hormone levels. Understanding the impact of eating disorders on a person’s health is often helpful to individuals and family members, encouraging individuals to make changes, seek help and treatment.
For information and support on eating disorders, head to the charity Beat
Last reviewed: May 2022
