I heard stretching and doing some yoga helps you look thinner. does that mean losing weight? how is this possible?

Theory: The belief is that through doing exercises like yoga and pilates, that you will lengthen your muscles and create an effect of looking longer and leaner. But i'm not sure how true that is. Yoga is a fabulous exercise for strengthening, toning and for relaxation. Used in conjunction with dietary modifications hopefully see weight loss as well.