My brother uses an app to track calories and get down to a moderate caloric deficit. It is impressive how over the course of a year he just slowly loses weight

My brother uses an app to track calories and get down to a moderate caloric deficit. It is impressive how over the course of a year he just slowly loses weight consistently. If he can just keep around a neutral caloric intake for the rest of his life he is set, but that has not happened in the past. Maybe this time (fingers crossed).