The study group consisted of 128 adults with schizophrenia on atypical antipsychotic medications.
Those who gained more than 10% of their pre-treatment weight were assigned into four groups: a placebo group, a group who took metformin, a group who took metformin and physical exercise and a group who took exercise.
The metformin plus exercise group had an average BMI decrease of 1.8, insulin resistance index decrease of 3.6 and lost 2cms in waist circumference
Those on placebo group had a BMI increase of 1.2, insulin resistance index increase of 0.4 and waist circumference increases of 2.2.
Journal of the American Medical Association (2008) 299: 185-193