Is Metformin (Metformin hydrochloride) approved for weight loss?

From the Guidelines

Metformin is not FDA-approved specifically for weight loss, and its use for this purpose is considered off-label. According to the most recent and highest quality study, metformin was associated with approximately 3% weight loss, and approximately 25% to 50% of participants achieve at least 5% weight loss 1. The study found that doses of metformin greater than 1500 mg are associated with the greatest weight loss. Metformin's pleiotropic effects include decreased inflammation, increased insulin and leptin sensitivity, and decreased hunger and ghrelin levels, especially with twice-daily dosing.

Key Points

• Metformin is primarily approved for treating type 2 diabetes, not weight loss
• The weight loss effect of metformin occurs through several mechanisms, including reducing appetite, decreasing intestinal absorption of carbohydrates, and improving insulin sensitivity
• Healthcare providers sometimes prescribe metformin off-label for weight management, particularly in patients with insulin resistance, prediabetes, or polycystic ovary syndrome (PCOS)
• Typical dosing for metformin starts at 500mg once or twice daily with meals, potentially increasing to 1000mg twice daily as tolerated
• Common side effects include gastrointestinal issues like diarrhea, nausea, and abdominal discomfort, which typically improve over time

Considerations

• For FDA-approved weight loss medications, options like semaglutide (Wegovy), liraglutide (Saxenda), or phentermine-topiramate (Qsymia) would be more appropriate choices
• Metformin's use for weight loss is not without risks, and patients should be closely monitored for potential side effects
• The American Heart Association has noted that metformin does not have FDA approval for weight loss in children and adolescents, and its use in this population should be approached with caution 1

From the FDA Drug Label

Mean change in body weight from baseline to week 29 was -1.4 lbs and -2. 4 lbs in the metformin hydrochloride tablets and placebo arms, respectively. Mean change in body weight from baseline to week 29 was 0.9 lbs, -0.7 lbs, and -8. 4 lbs in the metformin hydrochloride tablets /glyburide, glyburide, and metformin hydrochloride tablets arms, respectively. Mean change in body weight from baseline to week 16 was -3.3 lbs and -2. 0 lbs in the metformin hydrochloride tablets and placebo arms, respectively. Mean change in body weight from baseline to week 24 was 0.9 lbs, 1.1 lbs and 0.9 lbs, respectively.

Metformin is not approved for weight loss. While the studies show some changes in body weight, the primary indication for Metformin is the treatment of type 2 diabetes mellitus, not weight loss 2.

From the Research

Metformin Approval for Weight Loss

• Metformin is primarily used for the treatment of type 2 diabetes mellitus, but it has also been found to have benefits for weight loss 3.
• Studies have shown that metformin can lead to weight loss in both children and adults with obesity, with a greater reduction in weight/BMI observed in adults compared to children 4.
• The mechanisms underlying metformin's effects on obesity include reduction in hepatic gluconeogenesis, reduction in insulin production, modulation of hypothalamic appetite regulatory centers, alteration in the gut microbiome, and reversal of consequences of aging 3.
• Metformin has been found to be effective in reducing weight and improving insulin sensitivity in women with polycystic ovary syndrome (PCOS), and it is also being explored as a treatment for obesity-related complications such as hepatic steatosis, obstructive sleep apnea, and osteoarthritis 5, 6, 7.

Key Findings

• A systematic review of 15 pediatric and 14 adult studies found that metformin treatment for ≥6 months resulted in a greater reduction in BMI and weight compared to controls, with adults experiencing and maintaining small decreases in weight irrespective of duration of intervention 4.
• Metformin has been shown to reduce the progression toward type 2 diabetes in adults, with a significant reduction in risk ranging from 7 to 31% 4.
• The effects of metformin on weight/BMI vary, with smaller reductions in children than in adults, possibly due to differences in adherence, daily dosage, and insulin status 4.