green coffee bean extract or raspberry ketones???

These are the two studies cited by those marketing raspberry ketones. I’m not sure if you’ll be able to read all of them, since I’m logged into them through my university, but the abstracts should be there: http://www.sciencedirect.com/science/article/pii/S0024320505001281
http://www.sciencedirect.com/science/article/pii/S0024320505001281

First of all, neither study was controlled for bias and both examined the effect of raspberry ketones on weight GAIN over time on a very high fat diet rather than on weight loss. There’s a problem right there- those looking to LOSE weight are not going to be consuming these very high fat diets which alters how the body processes fats.

Another problem is that only the rats were fed EXTREMELY high doses of the raspberry ketones did have lower levels of weight gain and less fatty livers than those that were not. These doses were over 200x higher than what humans consume in their supplements! And that’s for a tiny rat! Those that were fed doses any lower showed no change in weight gain.

Also, a rats metabolism is far different than that of a humans. Rats consume and rapidly use large amounts of carbohydrates to survive. Humans are fat burners, meaning we don’t need as many carbs as constantly since our body can easily store energy in the form of fat. Therefore, something that prevents obesity and activates lipid metabolism in rodents will have different effects in humans, unless those rodents’ metabolisms have been altered to mimic those of humans.

Finally, there are no studies on humans and no detailed safety data. The manufacturers are the ones that are responsible for making their product safe, so supplements don’t need to be approved by the FDA before they go on the market. Probably not a good idea to take something for which there have been zero studies on humans.