Metformin for weight loss

Metformin works for type 2 diabetes and may affect weight by increasing insulin sensitivity, decreasing the amount of sugar your liver makes, and changing how much sugar your intestines absorb. The result is lower blood sugar levels after you eat and when you’re not eating. When you’re more sensitive to insulin, you feel hungrier. You also store more — and burn less — fat. When your insulin and blood sugar are at optimal levels, your body burns fat instead of storing it and you feel less hungry. 

Metformin may also affect hormones that impact hunger and reduce your appetite. It may even change the composition of your gut microbiome as part of how it works for weight loss.

Note that the FDA hasn’t approved metformin for weight loss because research findings on its effect on weight aren’t consistent. It’s sometimes used off-label for managing gestational diabetes (during pregnancy) weight gain issues caused by antipsychotic medications, preventing type 2 diabetes, and treating and preventing polycystic ovary syndrome (PCOS).

Metformin comes as a pill you take by mouth in both immediate- and extended-release (ER) formulas and as a liquid. Immediate-release tablets come in 500-, 625-, 850-, and 1000-milligram pills. The extended-release tablets come as a 500-, 750-, or 1000-milligram pill. The 500-milligram (5-milliliter) liquid comes in 4-ounce (118 milliliter) and 16-ounce (473-milliliter) bottles.

There’s no specific dose for metformin for weight loss or type 2 diabetes. You’ll most likely start at 500 milligrams twice a day or 850 milligrams once a day with meals. Your provider may have you increase your dose by 500 milligrams every 2 weeks up to a maximum dosage of 2550 milligrams. If you take more than 2000 milligrams, your provider may suggest taking it across 3 doses a day.

Dosing for children starts at 250 milligrams a day and increases 500 milligrams twice a day after a week up to a maximum dose of 850 milligrams twice a day, depending on age.

Compared to the 5% weight loss people have with metformin, people lose more on other drugs. Up to 10% on Ozempic — another medication for type 2 diabetes that helps people lose weight, up to 13.9% on Mounjaro, and up 20.9% on Zepbound.  

So metformin isn’t the most effective weight loss drug overall. But, if you can’t take other weight loss or antidiabetic medications, it’s a solid option. Your insurance company may also want you to take it for blood sugar control before approving another antidiabetic medication due to cost. 

Ozempic and Mounjaro are FDA-approved  improve glycemic (blood sugar) control for adults with type 2 diabetes. Zepbound is FDA-approved for weight loss or weight management in people with obesity and overweight when combined with a reduced-calorie diet and increased physical activity. Side effects for any of them may include, but aren’t limited to, nausea, vomiting, constipation, diarrhea, and headaches.

Only you and your healthcare provider can decide which medication is right for you and your needs.

Learn more about Metformin vs Ozempic for weight loss.