The invention provides compositions and methods for preserving lean body mass and promoting fat loss during weight loss. The methods comprise identifying an animal that is obese or overweight and administering to the animal a food composition in an amount less than the animal's baseline maintenance energy requirement (MER), the food composition comprising from about 30% to about 65% protein, from about 10% to about 20% carbohydrate, and from about 10% to about 25% fat； where the protein and carbohydrate are in a ratio effective for preserving lean body mass and promoting fat loss during administration of the food composition to the animal.
