Metformin weight gain
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Metformin and Weight Gain: A Comprehensive Review
Introduction to Metformin and Weight Management
Metformin, a widely prescribed medication for type 2 diabetes, has been extensively studied for its effects on body weight. While primarily used to manage blood glucose levels, metformin has shown potential in mitigating weight gain associated with various conditions and treatments, including antipsychotic medications and pregnancy.
Metformin and Antipsychotic-Induced Weight Gain
Efficacy in Children and Adolescents
Second-generation antipsychotics (SGAs) are known to cause significant weight gain in children and adolescents. Several studies have investigated the role of metformin in counteracting this side effect. A 16-week double-blind, placebo-controlled trial demonstrated that metformin effectively stabilized weight in children and adolescents who had gained more than 10% of their body weight due to SGA therapy, while those on placebo continued to gain weight. This finding is supported by a systematic review and meta-analysis, which found significant weight reduction in the metformin group compared to placebo after 4, 12, and 16 weeks of treatment.
Combination with Lifestyle Interventions
Combining metformin with lifestyle interventions has also been explored. A meta-analysis of randomized controlled trials (RCTs) revealed that the combination of metformin and lifestyle changes significantly reduced weight and body mass index (BMI) in patients with schizophrenia treated with antipsychotics, compared to metformin or lifestyle interventions alone. This suggests that a multifaceted approach may be more effective in managing antipsychotic-induced weight gain.
Metformin in Pregnancy and Postpartum Weight Management
A follow-up study on pregnant women with polycystic ovary syndrome (PCOS) indicated that those randomized to metformin gained less weight during pregnancy compared to the placebo group. However, these women lost less weight postpartum, and their infants were heavier at one year of age. This highlights the complex effects of metformin on weight during and after pregnancy.
Mechanisms of Metformin's Weight Effects
Insulin Sensitivity and Energy Balance
Metformin's ability to prevent weight gain is partly attributed to its effects on insulin sensitivity. In a study involving schizophrenia patients, metformin prevented increases in insulin and insulin resistance indices that were observed in the placebo group. Additionally, metformin's impact on energy balance has been linked to the hormone growth/differentiation factor 15 (GDF15), which reduces food intake and promotes weight loss.
Long-Term Effects and Energy Intake
Long-term studies have shown that metformin can mitigate weight gain in type 2 diabetes patients, even when added to insulin therapy. However, the prevention of weight gain by metformin does not appear to be due to reduced energy intake, suggesting other mechanisms are at play.
Safety and Tolerability
Metformin is generally well-tolerated, with gastrointestinal side effects such as nausea, vomiting, and diarrhea being the most common. These side effects were more frequent in the metformin group in studies involving children and adolescents treated with SGAs, but they did not lead to higher drug discontinuation rates.
Conclusion
Metformin has demonstrated efficacy in preventing and reducing weight gain associated with antipsychotic medications, pregnancy, and type 2 diabetes. Its effects are mediated through improvements in insulin sensitivity and energy balance, with GDF15 playing a significant role. While generally safe, metformin's gastrointestinal side effects warrant consideration. Further high-quality studies are needed to fully understand the long-term benefits and mechanisms of metformin in weight management.
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