RE: Meal Shakes? can that be all?
Gaining bodyfat is down to excess calories,doesn't matter if its from food or shakes consume to much your bodyfat will go up.
Ideally a combo of solid food and shakes at certain times,if your bodyfat starts to get out of hand then cut back on the amount of cals your eating.
What type of shake are you thinking of using,protien,mrp,weight gainer?