Cycle disorders
Eating disorders
Anorexia, bulimia and binge eating: how they relate to the cycle, PCOS and fertility
Eating disorders are mental illnesses with serious physical effects. They are not a matter of willpower and not an “extreme diet”. The three most common forms are anorexia nervosa, bulimia nervosa and binge eating disorder. In a large population study in the United States, 0.9% of women had anorexia at some point in their life, 1.5% had bulimia and 3.5% had binge eating disorder.
These disorders change hormones. Anorexia stops the cycle through the brain. Bulimia and binge eating are more common in women with polycystic ovary syndrome. This is why a gynecological endocrinologist is often the first doctor the woman sees: for a period that has stopped, an irregular cycle or a pregnancy that does not come. In a study of women before fertility treatment, 20.7% had a current or past eating disorder. Of these, 76.4% had not told their doctor.
What are the three forms?
Anorexia nervosa. The woman restricts food and has a low weight for her age and height. She has a strong fear of gaining weight and sees her body differently from how it is. Since 2013, according to the DSM-5 diagnostic manual of the American Psychiatric Association, amenorrhea is no longer needed for the diagnosis. There is also atypical anorexia: after a large weight loss, the woman has all the features, but her weight is still normal.
Bulimia nervosa. The woman has binge episodes: in a short time she eats much more than usual and feels a loss of control. Afterwards she tries to “make up” for it with vomiting, laxatives, fasting or excessive exercise. For the diagnosis, this happens at least once a week for three months. Weight is usually normal, so bulimia often stays hidden.
Binge eating disorder. The woman has binge episodes at least once a week for three months, without vomiting or other compensation. After the episode she feels shame and guilt. It is the most common eating disorder, and many women with it have a higher weight.
What are the three forms?
How serious are eating disorders?
Anorexia has one of the highest death rates among mental illnesses. In a meta-analysis of 36 studies, people with anorexia had about 5.9 times higher mortality than the general population of the same age. About 20% of deaths were suicides. In bulimia, mortality was about 1.9 times higher.
Vomiting and laxatives disturb the electrolytes, mainly potassium, and can cause dangerous heart rhythm problems. Starvation slows the heart and lowers blood pressure. This is why the assessment does not rely on weight alone. According to the British NICE guideline, the doctor does not decide on treatment based on body mass index alone and checks the electrolytes in every woman who vomits or uses laxatives.
How is anorexia linked to functional hypothalamic amenorrhea?
The cycle needs energy. When a woman eats less than she needs, the hypothalamus slows the pulses of the hormone GnRH. LH and FSH fall, the ovaries make little estrogen, and ovulation stops. This is functional hypothalamic amenorrhea. The body limits reproduction to save energy. The ovaries are not damaged, and the cycle can come back.
Anorexia is the most extreme form of this condition, but not the only one. Functional hypothalamic amenorrhea also occurs in women with normal weight, after a strict diet, intense exercise or stress. This is why the Endocrine Society recommends a detailed history of diet, eating disorders, exercise, perfectionism and mood in every woman with functional hypothalamic amenorrhea. In women with infertility of hypothalamic origin, a small study found a history of an eating disorder in 20 of 21, mostly anorexia. More in the article “PCOS and functional hypothalamic amenorrhea”.
The cycle returns when energy is restored. In a study of adolescents with anorexia, periods returned on average when weight reached about 92% of the expected weight. Of the girls who reached about 90%, 86% had a period within six months. An estradiol level above 110 pmol/L (30 pg/mL) showed that the cycle was returning.
The pill causes bleeding, but not a real cycle. According to the Endocrine Society, the doctor does not prescribe the pill only to bring back periods or to protect the bones. The pill hides the return of the cycle, and the bones may keep losing density.
What happens to the bones?
Without estrogen and with little energy, bones lose density. In a study of 130 women with anorexia, 92% had reduced bone density and 38% had values in the osteoporosis range at one or more sites of the skeleton. The loss is more severe when anorexia starts during puberty, because this is when bones should reach their peak density.
The main treatment is to restore energy and weight. The Endocrine Society recommends a bone density scan (DXA) after six months of amenorrhea. When the cycle does not return despite nutritional and psychological treatment, it suggests short-term transdermal estradiol with a cyclic progestogen, not the pill. It does not recommend bisphosphonates, denosumab or testosterone. The NICE guideline sees bisphosphonates as an option for adult women with long-term low weight and low bone density, but warns about the risk to the baby in a future pregnancy.
How are bulimia and binge eating linked to PCOS?
Here the link runs the other way from anorexia. A 2024 meta-analysis pooled 20 studies with 28,922 women with PCOS and 258,619 women without PCOS. Women with PCOS had 1.53 times higher odds of an eating disorder, and 2.88 times higher odds in the studies using the Rotterdam criteria. The odds of bulimia were 1.34 times higher, and the odds of binge eating disorder were also higher. There was no increase for anorexia. Disordered eating was more common at every weight, not only in women with a higher weight.
The relationship works in both directions. Insulin resistance and high insulin levels increase hunger and cravings for sweet food. In women with PCOS, the satiety hormones also work differently: after a meal, cholecystokinin rises less, and the regulation of ghrelin, the hunger hormone, is disturbed. The woman feels full later. In turn, binge episodes increase weight, and weight worsens insulin resistance and androgens.
The psychological side also plays a role. Excess hair, acne and weight affect body image. Many women with PCOS hear from a young age that they must lose weight, and they go from one diet to the next. According to the model of cognitive behavioral therapy, a strict diet keeps binge eating going: hunger and restriction lead to the binge, the binge brings guilt, and guilt leads to the next strict diet.
Bulimia can also confuse the diagnosis. Cycles of bingeing and vomiting disturb the periods, and the ovaries often show many small follicles on ultrasound. This is why the doctor always asks about eating behavior before diagnosing PCOS.
How do the disorders affect hormones?
Anorexia
Bulimia, binge eating and PCOS
Why does dieting in PCOS need care?
Weight loss improves the cycle, metabolism and fertility in many women with PCOS and a higher weight. The 2023 international guideline, however, sets a clear condition: the doctor considers eating disorders in every woman with PCOS, regardless of weight, especially when discussing lifestyle and weight loss. The guideline also asks doctors to be aware of weight stigma and how it affects the woman.
The authors of the 2024 meta-analysis warn that the lifestyle changes often recommended in PCOS can make recovery from an eating disorder harder. A very strict diet, constant calorie counting and daily weighing can trigger or worsen binge eating. The goal is a steady and gentle change, with regular meals and no bans, that the woman can keep for years. More in the articles “PCOS and weight” and “PCOS and quality of life”.
What does this mean for fertility and pregnancy?
Eating disorders often go unnoticed in fertility care. In a 2022 systematic review, the frequency of an active eating disorder in women in fertility treatment reached up to 35.7%, depending on the study. Women with ovulation disorders had more symptoms than other women with infertility.
Inducing ovulation in a woman with active anorexia is not the right answer. The Endocrine Society recommends ovulation induction only when body mass index is at least 18.5 and after efforts to restore energy balance. Pregnancy needs energy, and starvation harms both mother and baby.
In a Swedish study of 1.2 million births, anorexia, bulimia and other eating disorders were linked to more preterm births, more severe vomiting in pregnancy and a smaller head size in the newborn. Active anorexia roughly doubled the risk of anemia. The risks were higher when the disorder was active. This is why the NICE guideline advises women planning a pregnancy to eat enough, reach a healthy weight and stop binge eating, vomiting, laxatives and excessive exercise.
How is the diagnosis made?
The diagnosis starts with questions. A simple tool is the SCOFF questionnaire, with five questions about vomiting, loss of control, weight loss, body image and the place of food in daily life. Two positive answers point to a possible eating disorder. According to the NICE guideline, a questionnaire is not enough for the diagnosis. A mental health specialist makes the final diagnosis after a full interview.
The gynecological endocrinologist checks the effects on hormones: LH, FSH, estradiol, prolactin, thyroid, androgens when there are signs, and electrolytes. The doctor rules out other causes of amenorrhea and orders a bone density scan when amenorrhea lasts more than six months.
How is it treated?
The treatment of the eating disorder itself is psychotherapy. For adult women with anorexia, the NICE guideline suggests specialized cognitive behavioral therapy for eating disorders (CBT-ED) or two other structured forms of psychotherapy. For bulimia and binge eating disorder, it suggests guided self-help first and then CBT-ED. No medicine should be the only treatment.
The role of the gynecological endocrinologist is different and adds to psychotherapy. The doctor follows the cycle and the bones, chooses contraception, plans the right time for pregnancy and, in PCOS, treats insulin resistance without strict diets. Cooperation with the psychiatrist, the psychotherapist and the dietitian is essential.
The practice's approach
The doctor asks every woman with a cycle disorder, PCOS or infertility about diet, dieting, weight changes and exercise. The doctor does this without judgment, because many women do not talk about these things unless someone asks.
In PCOS, the doctor does not give weight-loss advice before ruling out an eating disorder. The goal is not a number on the scale, but a metabolism and a cycle that work, with a way of eating the woman can keep.
In functional hypothalamic amenorrhea, the doctor treats the cause and not only the period, protects the bones and plans a pregnancy only when the body is ready. Mental health specialists treat the eating disorder itself, in cooperation with the practice. The goal of the practice is a cycle that works, healthy bones and a way of eating without strict bans.
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