One of the best known fat burners available, raspberry ketone, is a natural substance that gives red raspberries their powerful aroma. Raspberry ketones cause the fat within cells to break down more effectively, helping the body burn fat faster. They also increase levels of adiponectin, a hormone that helps to regulate fat metabolism. Raising adiponectin levels helps people lose weight and lower the risk of many diseases like diabetes. The molecular structure of raspberry ketones is similar to the two well-known fat burning compounds, capsasin and synephrine.

Scientific studies have been performed to assess raspberry ketones as a weight loss aid in lab animals. Raspberry ketone supplements given to animals on a high-fat diet prevented the animals from gaining weight. The liver and visceral fat (“belly fat”) that surrounds organs was also less fatty, according to the paper published in the medical journal Life Sciences.

Another study showed raspberry ketones increased the breakdown of fat molecules within fat cells. The paper was published in the journal Planta Medica and reported that raspberry ketones stimulated fat cells to secrete more adiponectin (the fat regulating hormone).

Raspberry ketones cause changes in body fat and overall weight, and the U.S. Food and Drug Administration categorizes raspberry ketones as safe to use. In extremely high doses, a side effect of raspberry ketones can be inflammation, heart palpitations, and shakiness. Raspberry ketones may also interact with medicines such as those that regulate heart rate, cholesterol, and hormones. They can also lower blood sugar levels, so people taking drugs for diabetes should be monitored closely when taking raspberry ketones.