Supplementation is another thing and the most attractive supplements are the ones out there with a various mix of supplements. Check out this bunch from a popular fat loss supplement...
"Proprietary Thermogenic Complex 375mg† † (Caffeine Anhydrous 99%, Green Tea Extract 60% EGCG, Synephrine 96%, Pure Guggulsterones E & Z 99%, Sclareolide 96%, Yohimbine 99%, Vinpocetine 99%, Bioperine® 96%)"
What the $^&% is that? 375 mg's? You need substantially more green tea than that to have even a health effect, let alone a fat loss effect.
Caffeine is a popular one. Almost everyone either takes it straight up or in a combination to enhance fat loss. Most people think it's a good thing...it ain't.
In the European Journal of Clinical Nutrition (1998), Pizziol et al showed that 200mg of caffeine given to 30 healthy subjects in the 20 to 30-something age range increased glucose responses to an OGTT for the second, third, and fourth hours of the test. Interestingly, there was no impact on insulin.
In the Canadian Journal of Applied Physiology (1999), Battram et al showed increased insulin secretion but no increase in glucose area under the curve with caffeine administration and an OGTT.
Those are just two studies that show what happens when the typical amount of caffeine is ingested. Caffeine is a fat loss supplement only in small amounts. I'm not saying that it will prevent you from dropping weight but if you're taking more and more caffeine on a daily basis then you might on reconsider those five cups a day.