What's the Deal With Raspberry Ketones?

Pills and potions promising effortless weight loss never seem to go out of style. Jump online and you'll find raspberry ketones touted as a natural supplement to help you burn off pounds. However, before spending money on raspberry ketone drops, powders or other products, here's what you should know.


Ketone Hype

Raspberry ketones are aromatic compounds found within red fruits and berries. These compounds, which contribute to the fruity smell, also occur in other fruits such as kiwis, peaches and apples; and vegetables like rhubarb, explains Ginger Hultin, a registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics. Raspberry ketones are common ingredients used to flavor food and drinks.

But what does the smell of raspberries have to do with weight loss? Some laboratory research on rats and mice suggests that consuming super-high doses of raspberry ketones may help rodents stave off weight gain. However, that's a big jump to marketing claims that people who consume raspberry ketones will boost their fat metabolism and lose weight. Frequently, results from animal research fail to translate to women and men.


"Right now, there is no reliable scientific evidence that raspberry ketone improves weight loss when taken by people," Hultin says. "Importantly, there is insufficient reliable information available about the safety of raspberry ketone."

Kristin Kirkpatrick, a registered dietitian at Cleveland Clinic's Wellness Institute, would not recommended raspberry ketones, either: "Even though it's regarded as a fat-burning supplement, there is really no strong evidence that it does that." Overall, she says, "The scientific data in humans does not exist and has not caught up with the enthusiasm. I'd rather just suggest my patients eat actual raspberries, which are a whole food."

Whole-food diets may be the most important factor related to weight-loss success, Kirkpatrick adds, citing a new study in the latest issue of the Journal of the American Medical Association.

Ketone Confusion

It's easy to confuse several trendy but separate concepts related to ketones and weight loss. Raspberry ketones are just one type of ketone supplement. Other supplements containing what are called "exogenous" ketones are also available. Moreover, the controversial ketogenic diet, or keto diet, is becoming increasingly popular. Here's a quick breakdown of terms:

Ketosis. Within the body, ketosis is a process in which the body uses, or metabolizes, stored fat for energy. That results in byproducts known as "endogenous" ketones.

Exogenous ketones. Ketones that originate outside the body are called "exogenous" ketones. Used as ingredients in some weight-loss supplements, exogenous ketones include ketone salts (naturally made) and ketone esters (synthetic). Early research includes a small study on 20 participants who showed improvements in their blood sugar levels after consuming ketone ester-containing drinks.

"Ketones are a fuel source that may help maintain blood sugar levels and stave off hunger, which may ultimately help with weight loss," Maleah Holland, an assistant professor at Augusta University in Georgia, writes in an email. Holland, who studies the effects of the ketogenic diet and ketone supplementation, is currently conducting research on ketone salts.

Holland has found the ketone salt she is testing to be safe, according to blood work results from young, healthy adults. Ketones may affect each individual differently in terms of weight loss, she notes. Determining the specific mechanism behind potential weight loss – such as suppressed appetite or increased metabolism – will require more research, she says.


We’ve named some standouts, but you have to decide for yourself which diet is the best fit for you.

Ketogenic diet. With the keto diet, the theory is that by eating fewer carbs while taking in unusually high levels of fat, your body enters a state of ketosis. As a result, it burns down both dietary fat and stored body fat into ketones, ultimately causing you to lose weight.

However, the keto diet is difficult to follow. Many nutrition experts criticize the diet's lack of balance and call its high fat content unhealthy.

Raspberry ketones. The term "raspberry ketones" is a misnomer, according to Holland. "They are not ketone bodies and do not raise ketone levels in the body," she says. "Exogenous ketones, on the other hand, mimic ketone bodies produced in the [human] body and can raise your ketone levels."

It's a common misconception, Holland says: "People hear positive findings on exogenous ketones or a ketogenic diet, and purchase raspberry ketones thinking that is the same thing."


Evidence to Date

A 2010 study found that giving high doses of raspberry ketones to rodents increased the release of adiponectin, a hormone involved in fat metabolism. That built on a 2005 study of mice fed a high-fat diet that found increased fat breakdown and less weight gain among the mice who received raspberry ketones.

A 2016 study, funded by the National Raspberry Council and published in the Journal of Berry Research, found that high-fat fed mice given a variety of raspberry products, including ketones, appeared to have gained less weight than their raspberry-deprived peers.

In humans, so far, a single randomized controlled trial has analyzed the effects of a dietary supplement containing raspberry ketones on weight loss, according to the Office of Dietary Supplements, part of the National Institutes of Health.

A group of 70 overweight adults received either a weight-loss product containing multiple ingredients – including raspberry ketones – or a placebo, in the study published in April 2013 in the Journal of the International Society of Sports Nutrition. All participants followed a low-calorie diet and moderate exercise routine.

At the end of the eight-week trial, those taking the supplement lost nearly 4.2 pounds, compared with less than 1 pound for the placebo group. However, the results are considered inconclusive. Because only 45 participants completed the study, and because the supplement contained many other ingredients, it was impossible to sort out the effects from raspberry ketone alone, according to the NIH website.

Safety is another unknown. Typical diets only contain a few milligrams of raspberry ketones a day, the NIH summary points out. By contrast, dietary supplements provide anywhere from 100 to 1,400 mgs of raspberry ketones. "The safety of such doses has never been evaluated in humans," summary authors note.