I sometimes work with clients who’ve lost weight due to dental surgery, a digestive problem, stress, or an illness, and are trying to get back to a healthy weight. And as a sports nutritionist, I also work with pro athletes who tend to lose weight over the course of a grueling season. In all of these cases, the goal is to gain weight while optimizing health, and there’s a science to it. After all, the old phrase, “You are what you eat” is absolutely true – nutrients from food are literally the raw materials your body uses to construct new cells. A junk food-filled diet devoid of nutrients doesn’t give your body much to work with - I always say it’s like constructing a house with cardboard and tape instead of bricks and mortar. In other words, it’s not just about calories.