The point of the cabbage soup is that it is a) homemade, and made to a specific recipe, so no salt or fat added, and b) negative calorie, as in you burn more calories digesting the roughage than you absorb from it. Cup-a-soup, as others have said, is high in sodium and I suspect also in fat and calories, plus it contains no proper vegetables. So whilst you might lose weight simply because you are only eating soup, it's not the same thing. Also, the cabbage soup diet allows you to eat some other things as well, different things for each day. You should google it and have a look. If you really can't handle cabbage, another robust leafy green should do, kale for example. The important thing is that the soup should be full of vegetables and with no added fat or salt.