The only properly design ed , low bias and highly powered study found a weight increasing effect  of dronabinol in AN , while the other , using Δ9-THC at a high dose , found no effect and where the dose may have counteracted the weight gaining effects due to adverse events .
Anorexia nervosa ( AN ) is a psychiatric disorder with a high mortality and unknown etiology , and effective treatment is lacking .
For decades , cannabis has been known to cause physical effects on the human body , including increasing appetite , which may be beneficial in the treatment of AN .
To systematic ally review the literature for evidence of an effect of cannabinoids on ( 1 ) weight gain , and ( 2 ) other outcomes , in AN .
Dronabinol in severe, enduring anorexia nervosa: a randomized controlled trial.
OBJECTIVE The evidence for pharmacological treatment of severe , longst and ing anorexia nervosa ( AN ) is sparse and the few controlled pharmacologic studies have focused on a narrow range of drugs . The aim of the present study was to investigate the effects of treatment with a synthetic cannabinoid agonist on body weight and eating disorder-related psychopathological personality traits in women with severe , enduring AN . METHOD This add-on , prospect i ve , r and omized , double blind , controlled crossover study was conducted between 2008 and 2011 at a specialized care center for eating disorders . Twenty-five women over 18 years with AN of at least 5 years duration were r and omized to treatment with either dronabinol-placebo or placebo-dronabinol .  In addition to the st and ardized baseline therapeutic regime , the participants received dronabinol , 2.5 mg twice daily for 4 weeks and matching placebo for 4 weeks , separated by a 4-week wash-out period . Primary outcome was the mean change in body weight . Secondary outcome was score changes on the Eating Disorder Inventory-2 ( EDI-2 ) . Data were analyzed for the 24 patients who completed the trial . RESULTS During dronabinol treatment , participants gained 0.73 kg ( t = 2.86 , df = 22 , p < 0.01 ) above placebo without significant psychotropic adverse events . Dronabinol significantly predicted weight gain in a multiple linear regression including EDI-2 body dissatisfaction score and leptin . EDI-2 subscale scores showed no significant changes over time . DISCUSSION Dronabinol therapy was well tolerated . During four weeks of exposure it induced a small but significant weight gain in the absence of severe adverse events
The only properly design ed , low bias and highly powered study found a weight increasing effect  of dronabinol in AN , while the other , using Δ9-THC at a high dose , found no effect and where the dose may have counteracted the weight gaining effects due to adverse events .
Anorexia nervosa ( AN ) is a psychiatric disorder with a high mortality and unknown etiology , and effective treatment is lacking .
For decades , cannabis has been known to cause physical effects on the human body , including increasing appetite , which may be beneficial in the treatment of AN .
To systematic ally review the literature for evidence of an effect of cannabinoids on ( 1 ) weight gain , and ( 2 ) other outcomes , in AN .