You can lose weight by doing yoga, but the easiest way to lose weight is by doing something with a cardio element, which will cause you to get at least a little sweaty. I don't get as sweaty doing yoga as I do when I do step aerobics, but I like to shower afterward. The best kind of yoga for weight-burning will be one where you move fluidly and somewhat quickly through various postures, sort of like dancing. It's sometimes called "power yoga," which generally means that it's an exercise routine based on yoga principles but that it doesn't strictly adhere to one form of yoga. But there are some forms of yoga that involve more movement and thus more weight burning than others.