Among Lexie Manion’s memories of her junior year of high school in New Jersey was the experience of being regularly hassled by a school nurse who was trying to weigh her. The nurse, Manion recalled, was trying to get Manion’s weight on file — a common practice at schools across the United States, which aim to use the data to improve student health. But for Manion, who had an eating disorder, the experience was deeply distressing. The thought of getting on a scale in school — of someone other than her doctor handling this sensitive measurement — terrified Manion. It also triggered her eating di…