As with adults, no easy way to address weight with children

FILE - In this Monday, Oct. 29, 2018 file photo, kids eat lunch at an elementary school in Paducah, Ky. It is far easier to avoid gaining weight than to lose it, so getting kids to eat well and exercise is crucial. But how to do that effectively is extremely difficult _ and sensitive. (Ellen O’Nan/The Paducah Sun via AP)

NEW YORK — Red, yellow, green. It’s a system for conveying the healthfulness of foods, and at the center of a debate about how to approach weight loss for children.