Bulimia may lead to weight gain rather than loss due to binge eating, as purging doesn’t significantly reduce caloric intake. Weight changes are also possible during recovery.

Bulimia nervosa is an eating disorder in which people experience patterns of eating much more than a person typically would during a short period, known as binge eating, followed by “compensatory” behaviors, such as purging or excessive exercise.

People with bulimia may perform compensatory behaviors to try to relieve feelings of guilt or stress or to “clear out” the body after a binge eating episode, but these behaviors are unlikely to prevent weight gain.

Keep reading to learn more about weight gain with bulimia, including why it happens and how to get help with bulimia.

If you may have an eating disorder

If you’re preoccupied with food or your weight, feel guilt about food choices, or engage in restrictive diets, consider reaching out for support. These behaviors may indicate a disordered relationship with food or an eating disorder.

Disordered eating and eating disorders can affect anyone, regardless of gender identity, race, age, socioeconomic status, or other identities. They can be caused by any combination of biological, social, cultural, and environmental factors, not just by exposure to diet culture.

Consider speaking with a healthcare professional or contacting the National Alliance for Eating Disorders, which offers a daytime helpline staffed by licensed therapists and an online search tool for treatment options.

For general mental health support at any time, you can call the Substance Abuse and Mental Health Services Administration 24 hours a day at 1-800-662-4357 (or 1-800-487-4889 for TTY).

Having bulimia nervosa doesn’t necessarily lead to weight loss.

Often-cited research from 1993 found that vomiting after binge eating only removes between 33% and 50% of the calories a person has eaten. This is because food absorption begins in the mouth, esophagus, and stomach.

Other purging methods, like laxative misuse, also don’t reduce the amount of calories a person consumes. Instead, laxatives act on food already in the digestive tract by helping the stool absorb water or lubricating the stool and the intestinal walls so that the stool will pass more easily.

Laxatives don’t affect the amount of nutrients the body absorbs from food, and any weight loss associated with their use is temporary and typically comes from water loss.

Anticipating engaging in purging behaviors like vomiting or laxative misuse may lead a person to eat more during a binge eating episode.

These compensatory behaviors can also have other health effects, from changes in digestion to the wearing down of tooth enamel.

Bulimia nervosa can potentially lead to weight gain over time.

A small 2016 study found that participants with bulimia were significantly more weight suppressed and had a greater reinforcing value (the amount of “work” someone is willing to do to earn a reward) of food compared with participants who didn’t have the condition.

The study authors suggested this might mean that in people with bulimia, being at a lower weight than in the past may increase the “desire” for palatable foods, potentially increasing appetitive drive and leading to more binge eating.

A greater difference between a person’s current weight and their highest-ever weight was associated with increased weight gain, despite purging behaviors. It was also associated with having more binge eating and purging episodes.

The cycle of binge eating and compensatory behaviors may also cause metabolic changes that make weight gain more likely, and bulimia can lead to fluctuations between weight gain and weight loss.

Treatment for bulimia doesn’t focus on increasing or decreasing your weight.

Instead, the goal is to reduce binge eating and purging episodes and help you explore and manage any thinking patterns related to self-perception that may have contributed to bulimia developing.

Treatment can also involve considering and potentially reframing ways of thinking about food, as well as dedicated nutrition support.

Focus areas of treatment may include:

  • Talk therapy: A licensed therapist can provide mental health support through therapy. This therapy may involve exploring or reframing thoughts about yourself or your body, considering whether any of your relationships may be contributing factors, and recognizing and managing emotions.
  • Nutrition counseling: Part of your treatment may include counseling sessions with a licensed dietitian to adjust your eating habits and create nutritious meals.
  • Treatment for complications: You may need some medical or dental care for complications related to bulimia. This can include fluids for dehydration and electrolyte imbalances or treatment for damage to your teeth or internal organs.
  • Medication: A doctor may also recommend you try taking an antidepressant. Fluoxetine (Prozac) is approved to treat bulimia.

Bulimia can potentially cause weight gain.

Compensatory behaviors like purging are not effective at preventing weight gain, and eating large amounts within a short space of time and engaging in compensatory behaviors may cause metabolic changes that make weight gain more likely.

If you have bulimia nervosa or another eating disorder, help is available. Treatment can help reduce episodes and may help you consider or reframe thinking patterns that may be contributing to the condition. Consider speaking with a healthcare professional for advice.