The juices have next to nothing for calories or protein so how are you going to gain weight? You need protein to build body mass, and that was always a focus when we were in the weight crunch. Lots of protein and calories. I get the point about sugar, but if you lose too much weight they will not treat you at all, and you become much less likely to survive when you are not nutritionally viable. I've done the dance over sugar or not, etc. In this game all that really counts is making it through. I agree with the premise, but it's hard to pass up all those calories and protein in one of those milkshakes, especially if you can convince the person they actually want it. We did use an algae protein powder mixed with apple or grape juice for awhile, but he threw it up so many times I stopped. If he could keep it in it gave a real boost, and had the added benfits of the blue green algae, one of which is to increase NK cells in regular users. But it still didn't have the caloric count you might want.