I'm currently using grenades and they seem to work. I havent really started training yet so cant really comment on the fat burning properties. But they definetly give you a buzz! I take one in the morning and one in the afternoon, but dont take them too late or you wont sleep. i once took two in the morning with a can of red bull and wow! that stuff really kicks in. I bought mine for £35, but you can get them for £27.99 inc postage at
www.fat-pharm.com
Hope this helps