Nutritional intervention to prevent weight gain in patients commenced on olanzapine: a randomized controlled trial

Aust N Z J Psychiatry. 2005 Jun;39(6):479-86. doi: 10.1080/j.1440-1614.2005.01607.x.


Objective: Olanzapine is the most commonly prescribed atypical antipsychotic medication in Australia. Research reports an average weight gain of between 4.5 and 7 kg in the 3 months following its commencement. Trying to minimize this weight gain in a population with an already high prevalence of obesity, mortality and morbidity is of clinical and social importance. This randomized controlled trial investigated the impact of individual nutrition education provided by a dietitian on weight gain in the 3 and 6 months following the commencement of olanzapine.

Method: Fifty-one individuals (29 females, 22 males) who had started on olanzapine in the previous 3 months (mean length of 27 days +/- 20) were recruited through Peninsula Health Psychiatric Services and were randomly assigned to either the intervention (n = 29) or the control group (n = 22). Individuals in the intervention group received six 1 hour nutrition education sessions over a 3-month period. Weight, waist circumference, body mass index (BMI) and qualitative measures of exercise levels, quality of life, health and body image were collected at baseline at 3 and 6 months.

Results: After 3 months, the control group had gained significantly more weight than the treatment group (6.0 kg vs 2.0 kg, p < or = 0.002). Weight gain of more than 7% of initial weight occurred in 64% of the control group compared to 13% of the treatment group. The control group's BMI increased significantly more than the treatment group's (2 kg/m(2)vs 0.7 kg/m(2), p < or = 0.03). The treatment group reported significantly greater improvements in moderate exercise levels, quality of life, health and body image compared to the controls. At 6 months, the control group continued to show significantly more weight gain since baseline than the treatment group (9.9 kg vs 2.0 kg, p < or = 0.013) and consequently had significantly greater increases in BMI (3.2 kg/m(2)vs 0.8 kg/m(2), p < or = 0.017).

Conclusion: Individual nutritional intervention provided by a dietitian is highly successful at preventing olanzapine-induced weight gain.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Benzodiazepines / adverse effects
  • Benzodiazepines / therapeutic use
  • Bipolar Disorder / drug therapy*
  • Body Image
  • Body Mass Index
  • Depressive Disorder, Major / drug therapy*
  • Exercise
  • Female
  • Health Status
  • Humans
  • Male
  • Nutritional Physiological Phenomena*
  • Obesity* / chemically induced
  • Obesity* / diet therapy
  • Obesity* / prevention & control
  • Olanzapine
  • Quality of Life
  • Schizophrenia / drug therapy*
  • Weight Gain*


  • Benzodiazepines
  • Olanzapine