Source: Abnormal Psychology Textbook (University of Florida)
Difficulty: Intermediate | Prerequisites: Part 1 notes on Anorexia Nervosa and Bulimia Nervosa
Tags: binge-eating disorder, BED, other specified feeding or eating disorder, OSFED, night eating disorder, atypical anorexia, obesity, BMI, bariatric surgery, food addiction, DSM-5, abnormal psychology chapter 12
Beyond anorexia and bulimia, the DSM-5 recognises binge-eating disorder as a full diagnosis and introduces a catch-all category for presentations that cause real distress but do not meet the criteria for the three main disorders. Obesity is not classified as a mental disorder in the DSM-5, but it overlaps substantially with binge-eating disorder and is one of the largest public health concerns worldwide. This section connects the clinical picture to environmental, genetic, and behavioural factors that drive overeating and weight gain.
Binge-eating disorder looks like bulimia without the compensatory behaviours: the person binges but does not purge, fast, or exercise to offset it. Other specified feeding or eating disorder covers partial or atypical presentations. Obesity, while not a DSM-5 diagnosis, is closely linked to binge-eating disorder and is driven by a combination of genetics, environment, and behaviour.
Binge-eating disorder (BED)
Recurrent episodes of binge eating without the regular compensatory behaviours seen in bulimia. In simple terms, the person eats large amounts and feels distressed about it, but does not purge or fast afterwards.
Other specified feeding or eating disorder (OSFED)
A DSM-5 diagnostic category for eating-related presentations that cause clinically significant distress or impairment but do not meet the full criteria for anorexia, bulimia, or binge-eating disorder. Think of it as the "close but not quite" category, and note that these presentations tend to be just as severe.
Atypical anorexia nervosa
All criteria for anorexia are met, including significant weight loss, except that the individual's weight remains within or above the normal range. In simple terms, the person has lost a dangerous amount of weight and shows all the psychological features of anorexia, but their starting weight was high enough that they still look "normal."
Night eating disorder
An OSFED presentation where the person regularly eats excessive amounts after dinner and into the night, is highly distressed by the behaviour, and experiences insomnia. Differs from sleep-eating disorder because the person is fully awake and aware.
Obesity
Defined as a BMI of 30 or above. Not classified as a mental disorder in the DSM-5, but strongly associated with binge-eating disorder and multiple mental and physical health conditions.
Bariatric surgery
Surgical intervention for severe obesity (BMI 40+ with at least one severe health problem). A small pouch is created at the base of the oesophagus to limit food intake. The stomach may be stapled, banded, or bypassed. Results in substantial weight loss.
Food addiction
A concept supported by research showing that chronic exposure to ultra-processed, high-calorie food produces brain changes similar to those seen in drug addiction. People with behavioural signs of food addiction show brain activity patterns similar to those of obese individuals and drug addicts when viewing food images or consuming processed food.
Resembles bulimia in the binge-eating component, but the person does not regularly engage in compensatory behaviours (no purging, no fasting, no excessive exercise to offset the binge)
Some people eat continuously throughout the day with no planned mealtimes; others engage in discrete large binges
Binges are often triggered by stress, anxiety, or depression
Eating may be very rapid, and the person may appear almost in a daze
Individuals are often significantly overweight and express disgust about their bingeing
Common history of frequent dieting, participation in weight-loss programmes, and family obesity
Roughly 30% of people enrolled in weight-loss programmes have binge-eating disorder
Slightly more common in women than men, though the gender difference is less pronounced than in anorexia or bulimia
No clear racial or ethnic differences in prevalence
Higher rates of comorbid depression, anxiety, alcohol abuse, and personality disorders
Tends to be chronic, with a mean duration of about 8 to 14.4 years
First appeared in DSM-4 as a condition needing further research; promoted to a full diagnosis in DSM-5
Eating disorder symptoms are common among adolescent and young adult women, and many fall into partial or subthreshold presentations. Research on adolescents in Oregon found that those with partial-syndrome eating disorders (bingeing a few times a month but not weekly, being underweight but not severely, judging self-worth by weight without meeting full criteria) were just as likely to experience serious psychological problems as those with full diagnoses. These problems included anxiety, substance abuse, depression, attempted suicide, lower self-esteem, poorer social relationships, and lower life satisfaction. They were also less likely to earn a bachelor's degree and more likely to be unemployed.
DSM-5 created the OSFED category to capture these presentations. Its predecessor in DSM-4 was called "eating disorders not otherwise specified." OSFED presentations tend to be as severe and persistent as bulimia or anorexia.
The OSFED category includes:
Atypical anorexia nervosa: All criteria for anorexia are met, including significant weight loss, but the individual's weight is still within or above the normal range
Bulimia nervosa of low frequency or limited duration: All criteria for bulimia are met, but binge eating and compensatory behaviours occur less than once a week or for fewer than 3 months
Night eating disorder: Regularly eating excessive amounts after dinner and into the night; feeling an overwhelming desire to eat at night; frequent insomnia (may believe eating is necessary to fall asleep); not hungry in the morning and skipping breakfast. Begins in early adulthood, tends to be long-lasting, and is associated with being overweight and with depression. The person is awake and aware they are eating, which distinguishes this from sleep-eating disorder.
Defined as BMI of 30 or above
BMI formula: (weight in pounds x 703) / (height in inches, squared)
Not included in the DSM-5, but common among people with binge-eating disorder
Highly associated with numerous mental disorders and can be a risk factor for developing them
Can result from psychotropic medication side effects
Prevalence is increasing worldwide, especially in areas where the standard of living and access to fast food are rising
Among racial and ethnic groups in the US, Black populations have the highest rates, followed by Hispanic populations
Associated with coronary heart disease, hypertension, stroke, type 2 diabetes, and certain cancers
People with obesity face stigma that leads to lower quality of life, reduced likelihood of being hired, and increased bullying
Emotional distress from stigma can increase eating, creating a vicious cycle
Brownell's "toxic environment" thesis argues that we live surrounded by high-calorie, inexpensive, heavily marketed food, and that this environment drives obesity at the population level. Less physical activity combined with more eating compounds the problem.
Research supports the concept of food addiction: chronic exposure to ultra-processed food produces measurable brain changes, and people showing behavioural signs of food addiction display brain activity similar to that of drug addicts.
Genetic factors also play a role. Genes influence the number of fat cells, fat storage capacity, tendency to overeat, and brain activity in response to food. Genetic predisposition interacts with the toxic food environment: Stice's research demonstrates that individuals with certain genetic profiles are more vulnerable to obesity when exposed to environments rich in processed food.
Health programmes produce modest weight loss for men and women. Even modest loss improves cardiac functioning and diabetes risk, though people may be discouraged if they expect dramatic results.
Weight-loss drugs include sibutramine (Meridia), orlistat (Xenical), and rimonabant (Acomplia). These suppress appetite and support weight loss, but side effects are significant: gastrointestinal upset (orlistat), increased blood pressure and heart rate (sibutramine), and negative mood swings (rimonabant).
Low-calorie diets (900 to 1,200 cal/day) with prepackaged meals and increased physical activity are recommended for BMI 30 to 39. This combination produces more weight loss than self-selected conventional diets.
Bariatric surgery is an option for BMI 40+ with at least one severe health problem. A pouch created at the base of the oesophagus limits food intake. Results in substantial weight loss.
Proven prevention methods: eating more nutrient-dense foods, 30 minutes of daily physical activity, structuring the environment so healthy choices are easier, and being more active throughout the day.
Students often assume binge-eating disorder and bulimia are the same. The crucial difference is the absence of regular compensatory behaviours in BED.
A common mistake is thinking OSFED presentations are mild or less serious. Research shows they are typically just as severe and persistent as full-threshold diagnoses.
Students sometimes think obesity is listed as a mental disorder in the DSM-5. It is not, though it is closely associated with several mental disorders.
It is easy to overlook night eating disorder or confuse it with sleep-eating disorder. The distinguishing factor is awareness: people with night eating disorder are fully awake.
⚠️ Know the distinction between BED and bulimia: bingeing without compensatory behaviours.
⚠️ Be prepared to list what falls under OSFED (atypical anorexia, low-frequency bulimia, night eating disorder).
⚠️ The 30% statistic (proportion of weight-loss programme participants with BED) is commonly tested.
⚠️ Understand why obesity is relevant to abnormal psychology despite not being a DSM-5 diagnosis.
⚠️ Know the BMI thresholds: 30+ for obesity, 40+ for bariatric surgery candidacy.
True or false: Binge-eating disorder involves regular compensatory behaviours such as purging.
Fill in the blank: Roughly ______% of people in weight-loss programmes have binge-eating disorder.
True or false: OSFED presentations tend to be milder and shorter-lasting than full eating disorder diagnoses.
Fill in the blank: Obesity is defined as a BMI of ______ or above.
True or false: Night eating disorder differs from sleep-eating disorder because the person is awake and aware they are eating.
Answers: 1. False. 2. 30. 3. False (they are typically just as severe and persistent). 4. 30. 5. True.
Q: How does binge-eating disorder differ from bulimia nervosa?
A: Both involve episodes of binge eating. In bulimia, the person regularly engages in compensatory behaviours (vomiting, laxatives, fasting, excessive exercise) to prevent weight gain. In binge-eating disorder, the person does not regularly use compensatory behaviours.
Q: What is atypical anorexia nervosa, and why is it clinically important?
A: Atypical anorexia nervosa meets all criteria for anorexia, including significant weight loss, except that the individual's weight remains within or above the normal range. It is clinically important because the person can be just as medically and psychologically impaired as someone with a full anorexia diagnosis, yet their "normal" appearance may delay detection and treatment.
Q: Explain Brownell's "toxic environment" concept and its relationship to obesity.
A: Brownell argues that we live in an environment saturated with high-calorie, inexpensive, heavily advertised food. This environment, combined with decreasing physical activity, drives obesity at the population level. The concept is supported by evidence that food addiction produces brain changes similar to drug addiction.
Q: What are the treatment options for obesity at different BMI levels?
A: For BMI 30 to 39, low-calorie diets (900 to 1,200 cal/day) with prepackaged meals and increased physical activity are recommended. For BMI 40 or above with at least one severe health problem, bariatric surgery (stomach stapling, banding, or bypass) is an option. Weight-loss medications are also used but carry side effects.
Binge-eating disorder connects to the study of mood disorders, since depression and anxiety are common comorbidities and may trigger binge episodes. Obesity ties into health psychology and public health topics, particularly discussions of how environmental design (food availability, urban planning) shapes health outcomes. The genetic component of obesity connects to behavioural genetics and the broader theme of gene-environment interaction discussed across abnormal psychology.
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