Puffiness under eyes is basically caused due to fluid and fat. Puffiness results when a fat pad that cushions the eye begins to pull away from the bone of the lower eye and sags due to age. Heredity makes this more of a problem for some people.Retaining water can also cause puffiness, especially in the morning. Thus if you see puffiness under your eyes, that is an indication that you’re probably not getting enough water in your system and thus drink plenty of water.