Antipsychotic medications: Is weight gain inevitable?

Weight gain is a well-recognized side effect of antipsychotic medications, especially "atypical" antipsychotics, such as quetiapine (Seroquel), olanzapine (Zyprexa) and risperidone (Risperdal). The cause of such weight gain isn't fully understood. But it is likely that genetics and biochemical changes in the brain caused by antipsychotic medications play a role.

Some people who gain weight when taking antipsychotic medications may have inherited a particular gene variant that makes them more susceptible to antipsychotic-induced obesity. Animal studies also suggest that antipsychotics increase the activity of an appetite-regulating enzyme called AMPK. In addition, some researchers question whether certain antipsychotic medications may impair the body's ability to use insulin (insulin resistance).

If you gain weight after starting an antipsychotic medication, discuss this with your doctor. Do not stop taking your medication.

In many cases, such weight gain can be managed with dietary changes and increased physical activity. However, a 2008 study from China indicates that treatment with the diabetes drug metformin in addition to dietary changes and increased physical activity may be effective in reversing or reducing weight gain in some people who take antipsychotic medications. In addition, some antipsychotics are more likely than are others to cause weight gain, so it may be possible to switch to a different medication.