Metformin (Glucophage)
Commonly used for diabetes Type 2 and results in weight loss. More recently used in polycystic ovarian syndrome and also results in weight loss in those patients.
Mechanism of Action
Metformin is a biguanide. It reduces endogenous glucose production and may increase insulin sensitivity.
Dose
500-1700mg/day (common dose is 850mg BID)
Evidence
Systematic review of 9 RCTs lasting 15 days to 1 year
Subjects did not have Type 2 diabetes or polycystic ovarian syndrome
Inclusion criteria: BMI > 25 or waist to hip (W/H) ratio > 0.8
Metformin groups lost 0.2 - 3.6kg (0.4 - 7.9lbs.), i.e., a modest weight loss
Placebo groups lost up to 2.2kg (4.8lbs.)
How to Interpret This Research
There is currently insufficient evidence to promote the use of Metformin for weight loss in patients without Type 2 diabetes or polycystic ovarian syndrome.
Adverse Effects
Common: diarrhea, bloating, stomach pain, gas, constipation, unpleasant metallic taste in mouth, heartburn, headache, sneezing, cough, runny nose, flushing of the skin, nail changes, muscle pain
Uncommon, but serious: lactic acidosis, chest pain, rash
Reference
Levri KM, et al. Ann Fam Med. 2005 September; 3(5): 457-461