Raspberry ketones are said to be similar in structure to capsaicin (a natural chemical found to alter fat metabolism in several preliminary studies). Proponents claim that the compounds help trigger the breakdown of fat cells.
A study published in Planta Medica in 2010, found that raspberry ketones helped activate adiponectin (a hormone that regulates fat breakdown). In another study, mice were fed a high-fat diet for six weeks. Then, for the next five weeks, the mice were fed the same high-fat diet enriched with raspberry ketones. Results revealed that the addition of raspberry ketones help reverse the weight gain induced by the high-fat diet. Scientists who performed the study also found that raspberry ketones appeared to protect against the buildup of fat in the liver.