"Everyone on these heavy squat programs who drank enough of it (milk) gained weight. Yes, everyone we've heard of." -Dr. Randall J Strossen
Adding 1liter to 4 liters (roughly a gallon) per day is the simple GOMAD (Gallon Of Milk A Day) approach to mass gain. It is generally known as a suggestion to add a single liter per day each week and keeping a close monitor on fat gain, which can accelerate. For many people this is the only dietary change needed to stimulate growth.