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.
[See: 7 Diet Mistakes Sabotaging Your Weight Loss.]
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.
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.”
[See: 15 Best Weight-Loss Diets at a Glance.]
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.
Natural Advantage?
In February 2012, television personality Dr. Oz began promoting raspberry ketones as a weight-loss aid on his show, instantly provoking public interest.
People frequently ask Hultin for advice about using these and other weight-loss supplements. “Everyone wants it to be a little easier,” she says. “Because weight loss is really hard.” People are particularly interested in natural products to boost weight loss, she adds.
Along with raspberry ketones, popular natural products include garcinia cambogia extract (from the skin of the fruit), Hydroxycut (mixed plant and caffeine extract), green coffee bean extract, glucomannan (plant fiber), green tea extract and bitter orange.
Bitter orange, which contains a stimulant called synephrine, has been linked to individual cases of symptoms like fainting. However, evidence on side effects on the heart and cardiovascular system are inconclusive, according to the National Center for Complementary and Integrative Health.
The molecular structure of raspberry ketones resembles that of synephrine, Hultin says, noting that stimulant medications and supplements can interact with drugs used to treat diabetes or blood-thinning medications. “Always talk to your doctor before trying a product like this, in case it may interact with a medication or condition that you have,” she advises.
As with any of the dietary supplements flooding the market, quality and purity are hard to verify. Just how “natural” supplements really are is another issue. According to the website of USDA’s Agricultural Research Service, “While raspberry ketone occurs naturally, and is found in raspberry fruit, most is synthetically produced for use in commercial products as flavorings, fragrances, or dietary supplements.”
[See: What Not to Say When Someone Loses Major Weight.]
Consumers should understand that not all ketone-based weight-loss products are created equal, Holland cautions. “Some products undergo research to determine the product’s efficacy, making them more costly,” she says. “Before trying a product, do your own research on the company to determine if the product has been put through research trials. Claims on product labels are often written without any scientific backing.”
Hultin says it’s not necessarily that weight-loss supplements don’t work, but that much more evidence on safety and effectiveness is needed. From her professional perspective, she says, “In any human study I’m seeing, they’re combining [supplements] with diet and exercise. Diet and exercise is well-studied and proven that it works. Raspberry ketones are not well-studied and not proven that they work.”
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What’s the Deal With Raspberry Ketones? originally appeared on usnews.com
