Have there ever been studies done to show that trying to gain weight on a diet consisting of liquids is the same as trying to do so with solids? If not, what do you experts think? Been talking with my cousin about this when it came up earlier today, so I figured I'd ask here. From what I recall, calories in > calories out will lead to weight gain and, with proper training, muscle growth. Though, if someone drank shakes all day and used whey protein, I'd be skeptical as to how they'd gain muscle when the protein was digested so quickly. I tried to use all shakes awhile back, but I got sick of it quick, so I never found out if I could move the scale at all while doing so. Thoughts?