Zyprexa and Weight Gain

by on June 29, 2012


Zyprexa (olanzapine) is a prescription medication that is used for the treatment of psychological conditions, particularly schizophrenia and bipolar-mania disorder. It belongs to a new class of psychiatric drugs known as atypical antipsychotics. Although this medication is considered effective, it is known to cause some side effects. Weight gain is a common side effect of this medication.

What Studies Say?

According to clinical studies, about 22.2 percent of adults taking Zyprexa experience weight gain and about 40.6 percent in adolescent users. The average increase from the baseline weight is 7 percent of total body weight.

A new study published in 2009 revealed that children and adolescents taking atypical antipsychotics are at increased risk for rapid weight gain and metabolic changes which can lead to hypertension, diabetes, and other illnesses. According to the study, children and adolescents had an 8 to 15 percent weight gain within less than 12 weeks of treatment. The average increase is 1 to 1.5 pounds per week. Among the four different atypical antipsychotic drugs that were evaluated, Zyprexa showed the most severe weight increase and metabolic changes.

The reason for this weight increase is not exactly known. However, it is suggested that the weight gain is due to several factors that include the biochemical changes caused by antipsychotic drugs and person’s genes. Perhaps, this explains why some users are more susceptible to weight gain than others. Animal studies show that antipsychotic drugs increase the activity of a certain enzyme which is plays a role in regulating appetite.

Dosage Dependent

The amount of weight gained while on Zyprexa is thought to be dose dependent. In general, there is a direct link between how much and for how long Zyprexa is used, and how much weight is gained.   According to research by Dr. CB Nemeroff, a dosage of 5/mg of Zyprexa causes an average weight gain of approximately 15lbs.  Dosages above 20/mg per day have most frequently been associated with extra weight.

Patients should speak with their healthcare professional to discuss their options which may include a reduced dosage.

Managing Weight Gain

Although a moderate amount of weight gain (less than 20 pounds) may be expected during treatment, some users can gain a very large amount of weight which can lead to other health problems. Therefore, patients taking Zyprexa are advised to consult their healthcare provider if rapid weight gain becomes apparent while on treatment.

Having a healthy diet and regular exercise is one way of preventing weight gain due to antipsychotic medications. Healthcare providers recommend increasing intake of more nutritive foods such as fresh fruits and vegetables, lean meat and fibers, while reducing fats and carbohydrates. Usually, small amounts of weight gain can be easily managed with proper diet and regular exercise.

For severe weight gain, the healthcare provider may also recommend additional medication for weight management. A registered nutritionist or dietician may help correct problems in diet. In addition, a fitness program may be recommended to help counter the side effects of Zyprexa.

In case of a significant increase in weight accompanied by certain health conditions, the patient may require dose adjustments. Usually, weight gain due to antipsychotic drugs depends on the dose: the higher the dose, the more weight the patient gains. However, before your dose is adjusted, your healthcare provider will evaluate your condition. Do not reduce your dose or stop taking Zyprexa without consulting your healthcare provider.