The app, available on iOS and Android, allows teens to track what they eat and uses the Stanford University-developed "traffic light" system to rank foods as green ("go foods"), yellow (moderation advised) and red ("stop and think"). Users enter data like height, weight and age, and they can track their physical activity, too. WW acquired Kurbo in 2018 and has since added updates like breathing exercises and a Snapchat-inspired interface. It also added weekly video coaching, which teens can purchase through the app starting at $69 per month. The coaches are trained to spot signs of disordered eating or unhealthy weight loss, and WW says research supports the "traffic light" system as a healthy way to encourage weight loss.

While childhood obesity is a serious public health concern, a weight loss app for kids will undoubtedly receive criticism. Parents might also question how much data their teens are entering into the app. On the other hand, there are apps and devices to track everything your baby does and all kinds of tools to keep your kids on task. In a way, giving teens an app to track their food isn't surprising -- users will have to decide whether or not that's a good thing.