What are the benefits and risks of weight-loss medicines in children and adolescents?

Key messages

• Compared to placebo (a 'dummy' treatment with no active ingredient), weight-loss medicines may reduce body mass index (which measures whether someone's weight is in a healthy range) and weight slightly. Weight-loss medicines probably make little to no difference to the number of people experiencing unwanted or harmful events.

• We do not know if weight-loss medicines plus lifestyle changes are more effective than lifestyle changes alone, or whether they lead to any unwanted events.

• To better understand the benefits and risks, we need more studies that follow young people for at least one year and measure their physical and mental well-being.

What is obesity?

Obesity means having too much body fat. Obesity in children (0 to 9 years) and adolescents (10 to 19 years) increases the risk of several diseases in the short term and adulthood. Obesity also affects how young people feel about themselves and interact with others, often resulting in low self-esteem, anxiety, depression, and social difficulties.

How is obesity treated?

Obesity is a complex problem with many factors. Children and adolescents with obesity may benefit from lifestyle changes, such as improvements in diet and exercise, counseling, and behavioral support. Weight-loss medicines are typically only considered when lifestyle changes have not worked.

Several medicines are used for obesity in children and adolescents, including newer medicines called GLP-1 agonists, better known by brand names such as Wegovy and Ozempic. We considered the effects of all weight-loss medicines together.

What did we want to find out?

We wanted to learn if weight-loss medicines are better than a placebo (a 'dummy' treatment with no active ingredient) or lifestyle changes at:

• reducing body mass index (BMI) — a number calculated from a person's weight and height that indicates whether their weight is in a healthy range, expressed as kilograms per meter squared (kg/m²);

• reducing weight (kg);

• improving well-being.

We also wanted to find out if these medicines lead to:

• unwanted events;

• people leaving the studies early due to unwanted events;

• obesity-related health problems, including high blood sugar, high blood pressure, and unhealthy blood fat levels.

What did we do?

We searched for studies that compared weight-loss medicines with placebo, no treatment, another weight-loss medicine, or lifestyle changes in children and adolescents, and lasted at least three months. We compared and summarized the results of the studies and rated our confidence in the evidence based on factors such as study methods and the number of young people involved.

What did we find?

We included 37 studies with 4218 young people. Twenty-eight studies involved adolescents only. Eight included children and adolescents. One study planned to include children as well as adolescents, but did not mention their ages. Thirty-one studies compared weight-loss medicines to placebo. Six compared weight-loss medicines plus lifestyle changes (changes to diet, physical activity, or both) to lifestyle changes alone.

Main results

Compared to placebo, weight-loss medicines:

• may reduce BMI by an average of 1.8 kg/m², based on evidence from 25 studies with 3091 young people. This is a small reduction, and may not meaningfully improve young people's health;

• may reduce weight by an average of 5.47 kg (20 studies, 2380 people);

• probably make little to no difference to young people's well-being (4 studies, 741 people);

• probably make little to no difference to the number of people experiencing unwanted events, which was high in both groups: 872 of 1000 people given weight-loss medicines and 846 of 1000 given placebo experience unwanted events (8 studies, 1877 people);

• may make little to no difference to the number of people leaving studies early due to unwanted events: 36 people per 1000 given medicine leave early, compared to 24 people per 1000 given placebo (13 studies, 2213 people);

• may make little to no difference to obesity-related health problems (1 study, 51 people).

There are important differences in the reductions in BMI and weight for different weight-loss medicines.

We are very uncertain about the effects of weight-loss medicines plus lifestyle changes compared to lifestyle changes alone on:

• BMI change;

• weight change;

• the number of people leaving studies early due to unwanted events.

No studies in this comparison measured young people's well-being, the number who experienced unwanted events, and obesity-related health problems.

What are the limitations of the evidence?

For both comparisons, our confidence in the evidence for most outcomes was reduced because the studies used methods likely to introduce errors in their results.

For weight-loss medicines versus placebo, our confidence in the evidence for BMI and weight was also reduced because the studies' results varied. We had little confidence in the evidence about the number of people who left studies early due to unwanted events because it was based on only a few cases. We had only moderate confidence in the evidence for well-being because there were too few studies to be certain about the results.

How up to date is this evidence?

The evidence is current to July 2023. In June 2025, we checked the status of ongoing studies, and updated the results accordingly.