Weight gain is one of the most worrying side effects for young people taking certain medications for bipolar disorder.
These medicines, known as second‑generation antipsychotics, are very effective at stabilizing mood and reducing symptoms, but they can also increase appetite and cause rapid weight gain.
For many teens and children, this weight gain becomes distressing, affects self‑esteem, and can lead to long‑term health problems like diabetes and heart disease. It may even cause some young patients to stop taking their medication, making their mental health much harder to manage.
A major new study, the largest and longest of its kind, has now found a promising solution. Researchers report that metformin, a medication commonly used to treat type 2 diabetes, can help control weight gain in young people taking bipolar medications.
The results were published in The Lancet Psychiatry and led by experts at the University of Cincinnati and Cincinnati Children’s Hospital.
Metformin is not new—it has been used safely for decades to manage blood sugar. Scientists have also known for some time that metformin can help reduce weight gain in some situations. The MOBILITY study was designed to see whether this effect could help young people who need bipolar medication but struggle with treatment‑related weight gain.
One of the strengths of this study is that it was done in many different clinics around the United States, including community mental health centers that do not usually take part in research. This makes the results more realistic and useful for everyday medical practice.
The study enrolled 1,565 young people between the ages of 8 and 19. Everyone in the study received advice on healthy eating and exercise, because lifestyle support is important for anyone taking these medications.
But only half of the participants were randomly chosen to also take metformin. The researchers followed these young people for six months and then again at 24 months to see whether the medication made a difference.
The results were clear: those who received metformin showed a greater improvement in their BMI z‑scores, which is a way to measure changes in weight based on age, height, and gender. This means that metformin helped slow down or reduce weight gain better than lifestyle changes alone.
While the effect was described as modest, the researchers say it is meaningful—especially since the alternative is uncontrolled weight gain that can harm health for a lifetime.
Equally important, metformin was found to be safe and well‑tolerated. No major health problems were linked to the medication. The most common side effects were stomach issues, but many of these improved when patients took the medicine with food or switched to an extended‑release version.
The study’s findings support growing recommendations in the medical world. Several national and international guidelines now advise doctors to consider starting metformin at the same time as bipolar medication in youths who are overweight or obese.
Dr. Melissa DelBello, the lead investigator, explained that this research confirms what newer guidelines already suggest: metformin should be a standard part of care for these young patients.
This is especially important now, when weight‑loss medications like Ozempic are becoming more popular. While these drugs show strong results for adults, they have not been properly tested for long‑term safety in children or teenagers with mental health conditions.
They are also far more expensive and less accessible than metformin. For families and clinics with limited resources, metformin may be the best available option.
The MOBILITY trial faced significant challenges, including being partially conducted during the COVID‑19 pandemic.
Yet the study succeeded because of strong teamwork among researchers, doctors, caregivers, patients, and community mental health clinics across the country. It shows what can be achieved when everyone works together to solve an important health problem.
The study’s results strongly suggest that metformin provides real, practical benefits for young people who take antipsychotic medications. Weight gain from bipolar medication is not just cosmetic—it affects long‑term physical health, emotional wellbeing, and treatment success.
A safe and affordable medication like metformin offers a valuable tool for protecting young people from these risks. The effect on weight may be modest, but even modest improvements can make a big difference over many years.
Because it is well‑tolerated, widely available, and supported by updated clinical guidelines, metformin is likely to become a routine part of treatment.
However, the study also highlights the need for continued research, especially long‑term studies that look at health outcomes beyond weight alone. Overall, the findings support a shift toward more holistic and preventive care for youth with bipolar disorder.
If you care about diabetes, please read studies about Vitamin D and type 2 diabetes, and what you need to know about avocado and type 2 diabetes.
For more information about diabetes, please see recent studies about how to eat to prevent type 2 diabetes, and 5 vitamins that may prevent complication in diabetes.
Copyright © 2025 Knowridge Science Report. All rights reserved.
