TUESDAY, Jan. 8 (HealthDay News) -- Improved diet, more exercise and the diabetes medication metformin can help people suffering with schizophrenia control the weight gain that typically accompanies their medications, a Chinese study suggests.

Three months of both medication and lifestyle change resulted in a loss of two centimeters around the waist as well as improvement in other health measures, such as insulin resistance, the researchers report in the Jan. 9/16 issue of the Journal of the American Medical Association.

Metformin is typically prescribed to help control blood sugar levels in people with diabetes. Previous research has shown that metformin can prevent weight gain in people with diabetes and may help manage weight in some overweight people.

Doctors prescribe atypical antipsychotic (AAP) medications to manage a variety of psychotic disorder and behavioral disturbances, including schizophrenia. However, the drugs often also affect the body's metabolism, resulting in unhealthy cholesterol levels, weight gain and glucose intolerance.

A team based at the Mental Health Institute of the Second Xiangva Hospital, Central South University, China, tested the effect of metformin and lifestyle changes, together and separately, on the weight and insulin levels of 128 adults with schizophrenia. All the participants had gained at least 10 percent of their body weight after starting antipsychotic medications.

The participants were randomly assigned to one of four groups for 12 weeks, while continuing their medication: One group received a placebo or sugar pill; the second one received 750 milligrams per day of metformin; the third received 750 milligrams per day of metformin with lifestyle intervention; and the fourth went through the lifestyle intervention alone. The lifestyle interventions included health education, diet and exercise.

An analysis of the data found that patients in the combination group and patients who took either metformin or engaged in lifestyle change all reduced their weight, body-mass index (a measure of height and weight), waist circumference, insulin levels and insulin resistance.

The participants who took metformin and changed their diet and exercise saw a decrease of 1.8 in their body-mass index, 3.6 in insulin resistance and lost two centimeters in waist circumference. Metformin alone resulted in an average loss of 1.2 in body-mass index, 3.5 in insulin resistance and 1.3 centimeters from the waist. Those who only exercised and changed their diet saw a loss of 0.5 in body-mass index and 1.0 in insulin resistance, but they were no slimmer at the waist. People who took the placebo continued to increase in body mass, waist and insulin resistance, said the researchers.