Restoring Health Gradually with Wholesome Nutrition. Easily digested Iams ProActive Weight & Hairball Care is formulated to meet the unique needs of indoor cats. It's made with 10% less fat than Original formulas. Fewer calories in combination with fat-burning L-Carnitine, and a special blend of carbohydrates that keep pets feeling full, enables heavy cats to gradually return to a healthier weight. Whole grains, beets and rice support a healthy digestive system, and help reduce hairballs and litter-box odors.