Young people with obesity may soon have a powerful new tool to help them lose weight.

Results of a clinical trial released in the New England Journal of Medicine on Wednesday found that adolescents who got a weekly injection of a drug that reduces appetite lost an average of 14.7% of their starting bodyweight, while those who got a placebo and counseling on diet and exercise gained 2.7% of their initial weight. The trial included 201 young people ages 12 to 17 at three medical centers around the country and in Europe and Mexico.

By the end of the study, over 40% of the participants who got the drug, along with lifestyle counseling, were able to reduce their BMI by 20% or more, said study co-author Aaron Kelly, co-director of the Center for Pediatric Obesity Medicine at the University of Minnesota.

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