Well, yes, if they are used right. It won't necessarily work if you eat all your regular food as well, but they can help you lose weight if you substitute them instead of, say, cake or pizza.
Swimming can help you lose weight, but you have to have a routine. A routine is where everyday you go and swim for maybe an hour and then stop. Do this everyday for two weeks and you most likely will...
100% dance does help your weight..A Lot... it helps because of all the body movements at such speed that it burns fat and that why you sweat so much and get out of breath when dancing.