Christopher said:
^^It just can't work that way. The body needs bulk food and roughage to pass through its digestive system as a means of removing chemical wastes and toxins, and it would take extensive genetic engineering to give a human being a digestive system that could function in any way other than the one it's evolved for.
Besides, replicated food still has just as much bulk as other food, so if the same amount is going in and far less is going out, then everyone would keep getting fatter and fatter.