Weight-loss drugs are reaching children before the science does - critical summary review

What GLP-1 drugs are, and why they reach children at all

GLP-1 is a hormone the gut produces naturally. It helps control blood sugar, increases the feeling of fullness and reduces appetite. The drugs known in Brazil as "canetas emagrecedoras", the weight-loss pens, are synthetic versions that mimic that hormone: in the pancreas they stimulate insulin production, which is why they are also used for diabetes; in the stomach they slow digestion; and in the brain they switch on satiety, which leads to weight loss.

Wegovy, made by the Danish company Novo Nordisk, is the best known of them. Its active ingredient is semaglutide, and in Brazil the patent on that molecule expired in March, which has allowed similar and generic versions to enter the market at lower prices. The other GLP-1 approved for obesity in Brazil is tirzepatide, the active ingredient in Mounjaro, made by Eli Lilly, which acts on a second gut hormone as well and stays under patent until 2036.

None of this was designed with small children in mind. Wegovy is approved from the age of 12. That is the backdrop against which the news arrives, because a study published in early September showed the prescriptions did not wait for the age limit to move.

The numbers: from 0.03% to 9.3% in six years

The study, published in the journal Pediatrics and led by researchers at NYU Langone Health in the United States, looked at more than 3.5 million American children aged 8 to 11 who had obesity but not diabetes. Among them, GLP-1 prescriptions rose from 0.03% in 2019 to 9.3% in June of this year, an increase of more than 300 times.

In absolute terms, 20,282 children received a GLP-1 drug over the period. Most often it was Wegovy; doctors also prescribed Saxenda, from the same company, and Zepbound, from Eli Lilly. The researchers used Epic Cosmos, a national electronic health-records database covering more than 300 million patients in the United States. Epic had no part in the study.

The prescriptions are not approved for children under 12, but they are not clandestine either. Clinical guidelines allow the drugs to be used to treat obesity from the age of eight in certain cases, and the profile of who received them reflects that: 94% of the children prescribed a GLP-1 had severe obesity, and around 65% had at least one associated condition such as high cholesterol, high blood pressure or sleep apnoea.

Who gets the prescription, and who does not

The same data point to a second pattern, one that has nothing to do with medicine. Children living in higher-income communities were 55% more likely to receive one of these prescriptions, which the authors read as the emergence of disparities in access.

Allan Massie, a co-author of the study and associate professor of surgery at NYU Grossman School of Medicine, put it in terms of responsibility. In a statement, he said that "both doctors and health policymakers have a responsibility to ensure that these valuable and sometimes expensive treatments are available to more people than just those who have access to health plans and can afford the cost of appointments at paediatric clinics".

The trial that could change the approval

Days after those figures came out, Novo Nordisk released results from a separate clinical trial, this one testing Wegovy in children younger than the current approved age. It enrolled 165 children aged 6 to 11. Those in the treatment group received a weekly injection with a maximum dose of 1.7 mg or 2.4 mg of semaglutide, set according to their weight at the start.

At the outset, 85% of the participants had a body mass index in the severe obesity range. After about a year, 40% of those who received Wegovy were no longer classified as obese. In the placebo group, which also received an exercise programme and a reduced-calorie diet, none of the volunteers stopped meeting the criteria for obesity. According to the company, safety and tolerability among the younger children were consistent with what had been seen in studies with adults and adolescents.

Earlier studies had already found Wegovy effective and safe in older children, which is why it is approved from 12. This is the first clinical trial to examine its effects in younger children.

Ania M. Jastreboff, professor of medicine at Yale University, where she directs the obesity research centre and took part in the study, said in a statement that "childhood obesity is particularly concerning because of the immediate and lasting impacts on health, including a strong predisposition to obesity in adult life and an increased risk of the early onset of obesity-related complications".

The scale of the problem is not small. According to the latest atlas from the World Obesity Federation, an estimated 177 million children and adolescents aged 5 to 19 were living with obesity in 2025, a figure projected to reach 228 million by 2040. For Brazil, the atlas projects that by 2040 half of children and adolescents in that age range will be overweight, with 11.9% classified as obese.

What the adult data show

Part of what pushes doctors towards these drugs is what has been measured in adults. A study published in the August edition of the journal Annals of Oncology followed more than 229,000 American adults with obesity and without diabetes. Of those, 86,000 were using GLP-1 drugs and 143,000 had been advised on diet or exercise instead.

Over two years, the group on the drugs showed a 41% lower incidence of a set of 13 cancers associated with obesity than the group given only diet or exercise advice. Lower incidence was observed for pancreatic, endometrial, colorectal and thyroid cancer, and also for multiple myeloma and breast cancer. Both semaglutide and tirzepatide were associated with lower cancer incidence, but the study made no direct comparison between them, so it could not say which is more effective on that front. Specialists quoted in the coverage stressed that patients should use original versions and stay under medical supervision.

That is research in adults, and it says nothing about what happens to an eight-year-old who starts the same class of drug and may stay on it for decades.

What is known, and what is still unknown

What is established: prescriptions to children under 12 in the United States rose more than 300 times since 2019, reaching 9.3% of the 3.5 million children in the study by June; almost all of those children had severe obesity and about two thirds had an associated condition; clinical guidelines permit the use from age eight in certain cases; the first trial in children aged 6 to 11 found that 40% of those on Wegovy stopped being classified as obese after roughly a year, against none on placebo; and access is uneven, with children in wealthier communities 55% more likely to get a prescription.

What is not: long-term safety in this age group. Babak Orandi, the study's lead researcher and an obesity medicine specialist at NYU Langone Health, said long-term safety monitoring is needed to ensure the drugs remain safe and effective. He also noted that although the absolute number of under-12s on GLP-1 treatment is still low, use is growing fast. There is no timetable either for a regulatory filing below the age of 12.

What to do with this information

The next concrete step is a date. The detailed results of the trial in 6-to-11-year-olds will be presented at the annual meeting of The Obesity Society in November, in the United States, and that presentation is what would let independent specialists examine the data behind the headline figure. Whether a filing to regulators follows, and when, has not been announced.

For anyone with a child in this situation, the study itself points to what to ask about. Eligibility is not a matter of weight alone: the profile of who is being prescribed these drugs is dominated by severe obesity plus an associated condition, and it is reasonable to ask a doctor which criteria are being applied and why. Continuous monitoring is the second point, and it comes from the researchers themselves, not from outside critics. And the access gap the study found is worth keeping in view when dealing with health plans, since the researchers frame it as a question of who can afford appointments and coverage rather than of who needs treatment.

In Brazil the picture differs on one point that matters: semaglutide came off patent in March, and cheaper similar and generic versions have been entering the market. That changes price, not the age on the label.