Eating Disorders and Cannabis: Anorexia, Cachexia and Appetite

Eating Disorders and the Role of Appetite Regulation

• Eating disorders including anorexia nervosa, ARFID and cachexia secondary to cancer or HIV involve dysregulation of appetite, weight and nutritional status with serious medical consequences.
• The endocannabinoid system plays a well-established role in appetite regulation through CB1 receptor signalling in the hypothalamus and gut; this makes it a logical pharmacological target.
• Dronabinol (synthetic THC) has been approved in the US for AIDS-related anorexia and chemotherapy-induced nausea since the 1980s, providing historical evidence for cannabinoids’ orexigenic effects.
• UK specialist prescribers may consider cannabis for cachexia associated with cancer or HIV, where appetite stimulation and weight maintenance are clinical priorities.

The appetite-stimulating properties of THC are among the most robust and well-documented effects in cannabis pharmacology, with decades of clinical evidence supporting their use in cachexia management.

Cachexia and Palliative Use

• Cancer cachexia affects 50–80% of advanced cancer patients and is independently associated with reduced treatment tolerance and worse survival outcomes.
• THC’s orexigenic effects are mediated by CB1 receptor activation in the hypothalamus, which stimulates the release of appetite-promoting neuropeptides including ghrelin.
• Medical cannabis prescribed for cancer cachexia in the UK is typically flower or oil with moderate THC content; dosing is guided by appetite response and tolerability.
• The antiemetic properties of cannabinoids complement their appetite-stimulating effects in cancer patients who experience both nausea and anorexia simultaneously.

For cancer patients with cachexia, medical cannabis offers a multi-target approach — stimulating appetite, reducing nausea and providing analgesic support — within a single prescribed medication.

Anorexia Nervosa: Caution and Context

• Anorexia nervosa is a psychiatric condition in which distorted body image and fear of weight gain drive food restriction; it is distinct from medical cachexia and requires a different therapeutic approach.
• THC’s appetite-stimulating effects in anorexia nervosa have been investigated in small trials with limited and inconsistent results; the psychiatric complexity of the condition makes simple orexigenic prescribing insufficient.
• There is a theoretical risk that cannabis use in anorexia patients could reinforce avoidance behaviours or mask underlying anxiety without addressing the psychological drivers of restriction.
• UK specialist clinics should consult eating disorder psychiatrists before prescribing cannabis for anorexia nervosa; a multidisciplinary approach is essential.

Anorexia nervosa requires a fundamentally different clinical approach from cachexia; cannabis may have a limited adjunct role in selected patients but must be embedded within comprehensive eating disorder treatment.

UK Prescribing for Appetite and Eating Disorders

• Cachexia secondary to cancer, HIV or other severe illness is an accepted indication for medical cannabis assessment at UK specialist clinics.
• Pure eating disorder diagnoses without a physical comorbidity are unlikely to qualify for medical cannabis as a primary indication under current UK prescribing norms.
• Patients requiring cannabis for cachexia should provide documentation of their underlying diagnosis, current nutritional status and previous appetite-stimulating treatments tried.
• Oncology centres including those in London, Manchester and Bristol are increasingly familiar with medical cannabis as a palliative adjunct; a supporting letter from an oncologist strengthens a cachexia prescribing application.

UK patients with cachexia from serious illness have a credible pathway to medical cannabis prescribing as an appetite and nausea management adjunct; patients with primary eating disorders should approach the evidence with appropriate caution.