Schizophrenia and eating disorders: an under-recognised overlap

For a long time, eating disorders and schizophrenia were thought of as occupying different ends of a spectrum — one a young woman's illness, the other a young man's illness, with little overlap. The reality is messier. People with schizophrenia have eating disorders at rates considerably higher than the general population, the presentations are often atypical, and the picture is complicated by antipsychotic medications that profoundly alter appetite, weight, and metabolism. The result is a co-occurring problem that often goes unrecognised — until it is severe.

How common is the overlap?

Estimates vary, but recent reviews suggest rates of disordered eating in schizophrenia are several times higher than in the general population. A 2019 systematic review in the European Psychiatry journal by Kouidrat and colleagues found that around 5% of people with schizophrenia met criteria for binge eating disorder, while rates of subthreshold disordered eating were considerably higher — particularly around binge eating, night eating, and food-related obsessions.

How eating disorders look different in schizophrenia

Restrictive eating driven by delusions

Sometimes restrictive eating in schizophrenia is not driven by body image concerns but by delusional beliefs — that food is poisoned, contaminated, or carrying a hidden message. The behaviour can look like anorexia from the outside, but the underlying logic is psychotic rather than image-based. Treatment, accordingly, focuses on the delusion as much as the eating.

Food-related obsessions

OCD-spectrum food rules — about contamination, ordering, or specific food avoidance — are also more common in schizophrenia. These can shade into restrictive eating.

Antipsychotic-driven binge eating

Many antipsychotics — especially olanzapine, clozapine, quetiapine, and risperidone — cause profound increases in appetite, particularly for sweet and high-carbohydrate foods. Some patients describe feelings of intense hunger that don't subside after meals, leading to night eating or true binge eating disorder. This is a recognised pharmacological effect, not a personality flaw or weakness.

Pica and unusual eating patterns

Eating non-food substances (pica) is somewhat more common in serious mental illness, sometimes related to medication side effects or nutritional deficiencies. It warrants medical evaluation.

Atypical anorexia

Significant restriction without low body weight — particularly important to recognise as it carries similar medical risks but is often missed because the person doesn't fit the stereotypical anorexia presentation.

Why this overlap is missed

• Clinicians may not screen for eating concerns in psychosis
• Antipsychotic-related weight changes mask underlying disordered eating
• Restrictive eating gets attributed to negative symptoms or paranoia, with the eating disorder dimension overlooked
• Eating disorder services are not always equipped for serious mental illness, and vice versa

Why it matters

Eating disorders carry meaningful medical risks regardless of the underlying psychiatric context:

• Electrolyte abnormalities
• Cardiac arrhythmias
• Bone loss
• Refeeding syndrome with rapid nutritional restoration
• Worsened metabolic health from binge eating
• Greater risk of suicide

Assessment

A useful clinical question is to disentangle the function of the eating behaviour:

• Is it driven by body image concerns? — primary eating disorder
• Is it driven by delusional beliefs about food? — primarily a psychotic symptom
• Is it driven by pharmacological appetite changes? — antipsychotic side effect, possibly evolving into binge eating disorder
• Is it driven by negative symptoms (apathy, reduced appetite)? — primarily a schizophrenia symptom
• Is it driven by depression? — primarily a mood symptom

The same external behaviour can have different drivers, and each driver suggests a different treatment angle.

Treatment

Integrated team approach

Wherever possible, an eating disorder specialist working alongside the psychiatrist gives the best results. Communication between the two prevents the patient from getting bounced between systems.

Adjusting the antipsychotic

For binge eating disorder driven by an antipsychotic with strong appetite effects, switching to a metabolically lighter agent (aripiprazole, lurasidone, ziprasidone, brexpiprazole) sometimes reduces the eating compulsion considerably. This is always weighed against psychosis stability.

Medication adjuncts

• Topiramate: evidence for binge eating; some weight loss; can cause cognitive slowing
• Lisdexamfetamine: FDA-approved for binge eating disorder, but stimulant use in schizophrenia requires careful consideration
• GLP-1 agonists (e.g., semaglutide): increasingly used off-label for antipsychotic-related weight gain and binge eating
• Metformin: helps reduce weight gain, may dampen appetite
• SSRIs: for co-occurring depression or anxiety driving the eating

Psychotherapy

• CBT for eating disorders (CBT-E): well-evidenced, can be adapted for psychosis
• CBT for psychosis: addresses the delusional dimension when present
• Behavioural strategies: structured eating schedule, removing trigger foods from environment, planning around medication-related appetite peaks

Nutritional support

Working with a dietitian who understands both worlds — psychiatric medication effects and eating disorder treatment — can be valuable.

Practical first steps

1. Raise eating concerns explicitly with the clinician — they are unlikely to be asked about routinely
2. Be specific: how much, when, what triggers, what stops it
3. Ask whether antipsychotic adjustment might help
4. Request baseline labs: electrolytes, thyroid, metabolic panel
5. Ask about referral to an eating disorder service experienced with serious mental illness
6. Consider tracking eating patterns over a few weeks to give the clinician useful data

See also our pieces on weight gain management and dietary patterns for related context.

This article is for educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a qualified mental health professional. If you or someone you know is in crisis, call or text 988 in the US, or your local emergency number.