If you substitute the same amount of calories, why would anyone balloon? If anything, it's a better choice. Are you saying protein makes you balloon up while fat and carbs don't? I don't get your logic. If someone thinks adding protein without cutting elsewhere will be healthy, yea, that's stupid. But if you swap out 200 calories of fat/carbs for 200 calories of protein, there'll be almost no change in body weight. I'm not justifying what the person did and I personally think 19g of sugar in one drink is excessive.