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Aust N Z J Psychiatry. 2005 Jun;39(6):479-86.

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

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  • 1Peninsula Health, Department of Nutrition and Dietetics, Frankston Hospital, PO Box 52, Frankston, Victoria 3199, Australia.



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.


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.


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).


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

[PubMed - indexed for MEDLINE]
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