Metformin prevented additional weight gain in children who had gained 10 percent or more in less than a year while taking the antipsychotic drugs Zyprexa (olanzapine), Risperdal (risperidone) or Seroquel (quetiapine) according to a study from researchers at Cincinnati Children’s Hospital Medical Center in Cincinnati, Ohio, USA. Those given a placebo gained an average of 9 pounds, while those given metformin did not gain an additional weight.

Among schizophrenic patients on antipsychotic drugs who had gain an average of 54 pounds in less than six years, the average weight gain associated with various drugs was as follows. Zyprexa (olanzapine) was associated with an average weight gain of 57 pounds, Risperdal (risperidone) 55 pounds, Clozapine 54 pounds, and Geodon (ziprasidone) 35 pounds. 

Many antipsychotic drugs can cause considerable weight gain. An intense program of diet, exercise and counseling helped 17 chronically psychotic patients to lose an average of 13.2 pounds in six months according to a study from the Harvard Medical School in Belmont, Massachusetts.

Seroquel (quetiapine) causes an average weight gain of 7 percent or more in patients with schizophrenia or psychosis in 56 percent of patients according to a large, ongoing study of patients as noted in a new review paper about drugs that cause weight gain.

Zyprexa (olanzapine) causes a 7 percent weight gain or more in 40 percent of patients according to a new review paper about drugs that cause weight gain.

Zyprexa (olanzapine) caused an average weight gain of 7.9 percent in patients with bipolar disorder (manic-depression) after an average time on the drug of 2 years and 5 months according to a new review paper about drugs that cause weight gain.

Zyprexa (olanzapine) caused an average weight gain of 20.4 pounds in schizophrenic patients after an average time on the drug of 1 year and 10 months according to a new review paper about drugs that cause weight gain.

The antipsychotic drug Risperdal (risperidone) causes a 7 percent weight gain or more in 37 percent of patients according to a new review paper about drugs that cause weight gain.

Clozapine, an antipsychotic drug, causes an average weight gain of 5.3 pounds, but weight changes vary widely among individuals, ranging from a weight loss of 38.5 pounds and a weight gain of 28.4 pounds according to a new review paper about drugs that cause weight gain.

Below is a chart comparing weight gain during the first two-and-a-half months from various antipsychotic drugs.

Many antipsychotic drugs are associated with weight gain. Solian (amisulpride), Geodon (ziprasidone), and Abilify (aripiprazole) are associated with weight gains of less than 4.4 pounds, however, Zyprexa (olanzapine) has been associated with a large weight gain of between 8.8 and 22 pounds according to a paper from Washington University School of Medicine in St. Louis, Missouri.

The antipsychotic drug Clozaril (clozapine) caused a pair of female twins to gain over 100 pounds in 5.5 years according to a report out of Germany.

Schizophrenic patients given Abilify (aripiprazole) lost 3 pounds in six months compared to a weight gain of 9.4 pounds in patients given Zyprexa (olanzapine) according to a new study.

A weight gain of 22-pound from the use of the antipsychotic drug clozapine might cause as many deaths as lives saved from suicide according to a recent paper from researchers at University of Maryland School of Medicine.

The United States Federal Drug and Food Administration defines weight gain related to any given drug as an increase of 7 percent of bodyweight. Based on this definition, one study reported that a 7 percent weight gain was observed in 29 percent of patients treated with Zyprexa (olanzapine), 25 percent treated with Seroquel (quetiapine), 18 percent with Risperdal (risperidone), and 9.8 percent treated with Geodon (ziprasidone).

There is a case report of a person who gained 95 pounds in a year-and-two-months when put on the antipsychotic drug Clozaril (clozapine).

A standard dose of the antipsychotic drug Clozaril (clozapine) causes an average weight gain of 9.8 pounds in two-and-a-half-months according to recent analysis.

The antipsychotic drug Clozaril (clozapine) causes an average weight gain of 3.7 pounds in one month according to recent paper.

A standard dose of the antipsychotic drug Zyprexa (olanzapine) causes an average weight gain of 9.1 pounds in two-and-a-half-months according to recent analysis.

The antipsychotic drug Zyprexa (olanzapine) causes an average weight gain of 5.1 pounds in one month according to recent paper.

A standard dose of the antipsychotic drug Mellaril (thioridazine), used to treat schizophrenia, causes an average weight gain of only 7 pounds in two-and-a-half-months according to recent analysis.

A standard dose of the antipsychotic drug Risperdal (risperidone) causes an average weight gain of 4.6 pounds in two-and-a-half-months according to recent analysis.

The antipsychotic drug Seroquel (quetiapine) causes an average of weight gain of 9 pounds in two months according to recent study from the University of Miami School of Medicine.

The antipsychotic drug Risperdal (risperidone) causes an average weight gain of 2.2 pounds in one month according to recent paper.

The antipsychotic drug Seroquel (quetiapine) causes an average of weight gain of 4 to 12 pounds in six weeks according to recent review paper from Germany.