Short answer: A little, on average, but it is not approved for weight loss. In the Diabetes Prevention Program, people with prediabetes on metformin lost about 2% of body weight vs almost none on placebo, and the loss lasted about 10 years in those who kept taking it. The label trials in type 2 diabetes show mixed weight results, from a small loss to about 8 pounds.
The label (section 1) says metformin tablets are used with diet and exercise to improve blood sugar control in adults and children 10 and older with type 2 diabetes. Weight loss is not an approved use, and the label does not list weight loss as a benefit. Weight change appears only as a secondary number in its trial results.
| Trial | Metformin | Comparison |
|---|---|---|
| 29 weeks, adults with type 2 diabetes, vs placebo | -1.4 lb | -2.4 lb on placebo |
| 29 weeks, adults already on maximum glyburide | -8.4 lb on metformin alone | -0.7 lb on glyburide; +0.9 lb on the combination |
| 16 weeks, ages 10 to 16, vs placebo | -3.3 lb | -2.0 lb on placebo |
In the first trial, people on placebo lost slightly more than those on metformin. The label does not say why these trials differ, and they were not designed to test weight.
The best data on metformin and weight come from the Diabetes Prevention Program (DPP), which randomly assigned 3,234 adults with raised blood sugar but not diabetes to placebo, metformin 850 mg twice a day, or an intensive lifestyle program. Their average body mass index was 34. Over about 2.8 years, metformin cut new diabetes by 31% vs placebo and the lifestyle program by 58%.
A later report on the DPP and its follow-up study found that during the trial, people on metformin lost 2.06% of body weight vs 0.02% on placebo. In the open-label years after, weight loss stayed greater with metformin (2.0% vs 0.2%). The amount lost was linked to how consistently people took it, and the authors said the loss lasted for at least 10 years of treatment.
For a 200-pound person, 2% is about 4 pounds. That is much smaller than with GLP-1 medicines; see metformin vs Ozempic.
Metformin's most common side effects are in the gut. In a label trial, diarrhea affected 53% on metformin vs 12% on placebo, and nausea or vomiting 26% vs 8% (section 6.1). The patient information says these usually ease with time and that taking metformin with meals helps. The DPP follow-up report found stomach symptoms were more common on metformin and declined over time.
If weight is a goal, that conversation belongs with your prescriber, who can weigh metformin against approved options. Logging weight weekly alongside your doses makes any trend clearer; Dose Track keeps both on one timeline.
Read more on Dose Track: Metformin side effects · Metformin vs Ozempic · Berberine vs metformin · Weight loss: what the evidence shows · Metformin dosing schedule