Easy. Work out hard and don't eat enough. Bodybuilders preparing for contests also lose a lot of weight (mostly fat) shedding pounds but they do in fact lose some (or in some cases a lot) precious muscle as well. Check out
www.gettinglean.com. It's a good site if you can navigate around all the advertisements. I'm like Carrera. If I shoot ball (basketball) for a while I swear I sweat off my pecs instead of fat around my waist.