At 17, Israel McKenzie was so burdened by obesity that he stopped going to high school in person and was embarrassed to speak to people at his restaurant job. “I was in a really dark place,” says McKenzie, whose weight had climbed to 335 pounds on his 6-foot-1 frame, despite repeated efforts to diet and exercise. “I had given up hope.” But last year, the weight-loss drug Wegovy helped him shed 110 pounds in nine months, making the rural Tennessee teen part of a surge of adolescents and young adults using diabetes and obesity medications known as GLP-1 receptor agonists, new research shows.