Background

Raspberry ketone is a chemical compound from, you guessed it, raspberries. Since it doesn’t occur naturally in high amounts, it is often produced industrially (Source: http://en.wikipedia.org/wiki/Raspberry_ketone). Apparently the substance has a chemical structure similar to capsaicin, which is found in red pepper and believed to burn fat (Source: http://www.foodnavigator.com/Science-Nutrition/Raspberry-the-fat-busting-fruit).

Clinical Studies 

The one study that could be found looked at whether or not raspberry ketone could prevent obesity and activiate lipid metabolism in mice. In this 2-part study, one group of mice was fed a high-fat diet with .5, 1, or 2% raspberry ketone for 10 weeks. A second group was fed a high-fat diet for 6 weeks and then for the next 5 weeks was fed the same diet with 1% raspberry ketone. According to the study,

 RK prevented the high-fat-diet-induced elevations in body weight and the weights of the liver and visceral adipose tissues.

The study concluded that raspberry ketone can not only prevent but also improve obesity (Source: Life Sciences, 2005, 77(2), 194-204).

Conclusion

Since results of only one study could be found (and remember, it was conducted using mice), this review is staying with a neutral conclusion regarding the effectiveness of raspberry ketone on weight loss. Until studies are conducted in humans, there isn’t any conclusive evidence for raspberry ketone.