I've moved this thread from Recipes to Buyer Beware so more people could have the chance to respond.
You might want to check out a few threads here on the forum, specifically this one:
http://www.3fatchicks.com/forum/showthread.php?t=32108
Basically, like Jiff said, these pills are risky to use, even without the ephedra they used to contain prior to the US ban. At best, I'd say that any 'productive' effects are only temporary.
And don't get conned by the multipage "articles" you see in the fitness mags for Hydroxycut. These are ADS, and the before and afters for the most part (if not entirely) are FITNESS MODELS who get PAID to do these kind of ads. In fact, their contracts generally state that they be given 12 weeks advance notice prior to the ad shoot so they can get into the 'after' condition you see in the photos - not by using the product they're pushing so much as by some very rigorous, unhealthy 'competition dieting' (the same kind of diet and exercise regimen that competitors in fitness and bodybuilding contests undergo prior to their contest dates). This causes a TEMPORARY weight loss, largely through water loss, and can really do a number on your body including your thyroid, making it more and more difficult over time to lose any regained weight. So be VERY careful and don't be taken in by those ads!