One whose diet mainly consist of chips, cakes, cookies, soft drinks, French fries, hamburgers, hot dogs, pizza and cold cereals; and just so happens to stay in good shape. (Brand usually does not matter when selecting foods.)
Rick is the ultimate snackatarian. His daily meals usually include cookies and Sprite for breakfast, pizza, coke and chips for lunch, and a bowl of Cap'n Crunch for dinner. Only a snackatarian can eat like that and never seem to gain weight.