L Carnatine

If you are more interested in fat burning, the key is to make sure that you keep your metabolism up all day. One way is to gain muscle mass. Another way is to increase blood flow via exercise and intake of specific things. Both green tea and L-Carnitine (L-Tartate) combined will make a decent energy concoction, increasing blood flow. Correct me if I'm wrong, but I believe green tea is effective at dilating blood vessels while L-Carnitine can raise heart rate and blood pressure.

Also, your metabolism slows down about every hour or so. Just remember to take 5 minute breaks to walk around and get the blood flowing again in your every day life.

L-Carnitine decreases fatigue so that you can go longer working out and stay awake longer. It's also a temporary anti-depressant for some people (including me). When I had the money, I would take it when I woke up and 1/2 before I worked out...along with ginkgo which helps with blood flow too.

As a little forewarning, sometimes my chest would hurt if I didn't take L-Carnitine with Eluthero (not recommended) or Green Tea. I'm not sure why that was, but it might be because those two things promote blood flow in veins...but I have no idea.