Metformin for Weight Loss

Metformin is cheap and widely prescribed — but does it actually cause weight loss, and how does it stack up against the GLP-1 drugs everyone’s talking about? Here’s the honest answer.

The short answer

Metformin causes modest weight loss — about 1–3 kg (~3–5%) on average — but it’s not FDA-approved for weight loss; it’s a diabetes drug used off-label, especially for insulin resistance or PCOS. For significant weight loss, GLP-1 medications are far more effective (semaglutide ~15%, tirzepatide ~21%). If real weight loss is your goal, a GLP-1 is the evidence-based route.

Metformin vs GLP-1 weight-loss efficacy
Medication	Avg. weight loss	FDA weight-loss approval	How it works
Metformin	~3–5% (1–3 kg)	No (off-label)	Lowers glucose production / insulin resistance
Semaglutide (Wegovy)	~15%	Yes	GLP-1: curbs appetite, slows gastric emptying
Tirzepatide (Zepbound)	~21%	Yes	GLP-1 + GIP: strongest appetite effect

Does metformin cause weight loss?

A little. Metformin is generally weight-neutral to mildly weight-reducing — most people lose about 1–3 kg over several months, with effects strongest in those with insulin resistance. It’s a legitimate, inexpensive option, but weight loss is a side benefit, not its purpose.

When metformin makes sense

Metformin can be a good fit if you have type 2 diabetes, prediabetes, PCOS, or insulin resistance, want a low-cost generic, or can’t take a GLP-1. Clinicians sometimes use it alongside a GLP-1. It’s just not the most powerful tool for weight loss alone.

Why GLP-1 is more effective — and how to get it

For meaningful weight loss, GLP-1 medications win clearly: semaglutide (~15%) and tirzepatide (~21%) far exceed metformin. Compare them in best GLP-1 for weight loss, and get one through a licensed telehealth provider if appropriate — start with the options below or our 60-second quiz.

Want bigger results? Compare GLP-1 options

Common questions about metformin for weight loss

How much weight can you lose on metformin?

On average, modestly — roughly 1–3 kg (about 3–5% of body weight) over 6–12 months, though some people lose more. Metformin is generally weight-neutral to mildly weight-reducing, not a dedicated weight-loss drug. For comparison, semaglutide averages ~15% and tirzepatide ~21%.

Is metformin or Ozempic/Wegovy better for weight loss?

For weight loss specifically, GLP-1 medications (Ozempic/Wegovy semaglutide, Zepbound/Mounjaro tirzepatide) are significantly more effective — often 3–5× the average weight loss of metformin. Metformin can still be a good fit for insulin resistance, PCOS, or prediabetes, and is much cheaper. The best choice depends on your goals and health — decide with a clinician.

Can you take metformin and a GLP-1 together?

Sometimes, yes — clinicians do combine them in certain cases (for example type 2 diabetes or PCOS), and they work by different mechanisms. Whether that’s right for you is an individual medical decision; never combine prescriptions without your prescriber’s guidance.

Is metformin FDA-approved for weight loss?

No. Metformin is FDA-approved for type 2 diabetes and is used off-label for weight management (often with insulin resistance or PCOS). GLP-1 drugs like Wegovy and Zepbound are FDA-approved specifically for chronic weight management.

Sources & freshness

Efficacy reflects published metformin weight-loss data (~1–3 kg / ~3–5% average; off-label) and GLP-1 trials (STEP-1 semaglutide ~15%, SURMOUNT-1 tirzepatide ~21%). Verified 2026-06-30. Educational only, not medical advice.

Medication

Avg. weight loss

FDA weight-loss approval

How it works

Metformin

~3–5% (1–3 kg)

No (off-label)

Lowers glucose production / insulin resistance

Semaglutide (Wegovy)

~15%

Yes

GLP-1: curbs appetite, slows gastric emptying

Tirzepatide (Zepbound)

~21%

Yes

GLP-1 + GIP: strongest appetite effect