Raspberry ketone supplements have become increasingly popular as fat burners.

According to the supplement companies that sell them, they do this by enhancing fat burning and altering your body’s chemistry to limit fat gain and decrease food intake.

Many are leery of these claims, though.

Skeptics believe there’s no good evidence that raspberry ketones help humans lose weight and that we still know little about their safety.

Are supplement companies telling porkies, or are supplement stick-in-the-muds being unnecessarily pessimistic?

Get an evidence-based answer in this article.


What Are Raspberry Ketones?

Raspberry ketone is a compound found in raspberries that gives the fruit its smell. 

It’s been used in the cosmetics industry to create fragrances and as a flavoring in food manufacturing for decades.

In recent years, raspberry ketones have become a popular weight-loss supplement. Raspberry ketone supplements typically come in three forms: raspberry ketone pills, raspberry ketone drops, and raspberry ketone tea.

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Raspberry Ketones: Benefits & Fat Loss Effects

The most common reason people take raspberry ketones is to accelerate weight loss.

Raspberry ketone is chemically similar to other natural substances such as capsaicin, which is found in red peppers, and synephrine, which is abundant in bitter orange.

Studies show that capsaicin and synephrine can help increase metabolic rate in humans, leading some people to believe that raspberry ketone will have a similar effect.

This idea has some scientific basis, too.

Several rodent studies show that raspberry ketone enhances “fat mobilization,” which means it helps fat cells release their stored energy, and increases levels of adiponectin, a hormone released by fat cells that plays a role in fat burning, blood sugar regulation, and insulin sensitivity.

Other studies in rats show that raspberry ketone biases the expression of hormones, hormone receptors, and a host of other chemicals to decrease fat gain, fat cell size, and food intake and increase fat loss.

However, while these results are encouraging, it bears remembering that humans and rodents have very different physiologies. As such, it would be foolish to assume raspberry ketones will produce the same results in Homo sapien as Rattus rattus (yes, that’s the scientific name of a rat species) without testing it first.

And this is where the argument that raspberry ketones are an effective fat-loss supplement runs aground.

To date, no studies have investigated how raspberry ketones affect human metabolism—at least not in isolation.

The only study to examine raspberry ketones and fat loss in humans was conducted by scientists at ​​The Center for Applied Health Sciences. In it, overweight men and women took a fat-loss supplement containing raspberry ketone, caffeine, capsaicin, garlic, ginger, and bitter orange, followed a calorie-controlled diet, and exercised 3 days per week for 8 weeks.

The results showed that the people who took the fat-loss supplement lost significantly more body fat than those who took a placebo (-6.4 lb vs. -2 lb).

However, because the supplement contained compounds such as caffeine, capsaicin, and bitter orange (synephrine), which all increase fat burning in and of themselves, it’s impossible to know whether raspberry ketones contributed to the superior weight loss.

It’s also worth noting that the study was funded by the supplement company that makes the fat burner the participants used. While this doesn’t guarantee shenanigans, it makes it more likely that the results are colored by financial interest. 

Thus, raspberry ketone is an interesting molecule that shows potential as a fat-loss supplement in rodents . . . and that’s about all science shows at the moment.

There’s no reason to believe it has a similar effect in humans, though, which is why it’s not worth taking.

If you’d like specific advice about what science-backed supplements you should take to reach your fat-loss goals, take the Legion Supplement Finder Quiz, and in less than a minute, you’ll know exactly what supplements are right for you. Click here to check it out.

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Raspberry Ketones: Side Effects

Because of the lack of human studies, we don’t know much about the safety and side effects of raspberry ketones.

Studies show that taking large doses of raspberry ketone is toxic to rodents.

For example, one study showed that when researchers gave mice 291 mg of raspberry ketone per pound of body weight, 43% died.

Another study found that when researchers gave obese mice doses of ~150 and ~227 mg of raspberry ketone per pound of body weight, ~68% and 50% died, respectively. It’s strange that fewer mice died after taking the higher dose, but the point remains it’s quite lethal in excessively high doses, which is true of all substances.

Most over-the-counter raspberry ketone supplements contain 1,000-to-1,400 mg of raspberry ketone, which is far less than the doses used in these rodent studies.

That said, there’s no research to suggest this is a safe or effective dose for humans.

Based on our understanding of how raspberry ketones work in the body, they probably aren’t safe for . . .

  • Diabetics because they may reduce blood glucose, increase insulin, and alter insulin sensitivity
  • People taking anti-inflammatory medication because they may reduce the activity and expression of various inflammatory compounds
  • Cancer patients, particularly people receiving androgen deprivation therapy or those using antiandrogens or receiving hormone therapy, because they may inhibit androgen-receptor activity

Better Alternatives to Raspberry Ketones

There’s no evidence that raspberry ketones help humans lose weight. As such, there’s no reason to add them to your weight-loss regimen.

If you want to take science-backed fat-loss supplements, try these instead:

  • 3-to-6 mg of caffeine per kilogram of body weight per day. This will raise the number of calories you burn and also increases strength, muscle endurance, and anaerobic performance. If you want a clean, delicious source of caffeine that also contains five other ingredients that will boost your workout performance, try Pulse.
  • 0.1-to-0.2 milligrams of yohimbine per kilogram of body weight before fasted workouts (if you choose to train fasted). This increases fat loss when used in conjunction with fasted training, and is particularly helpful with losing “stubborn” fat. If you want a 100% natural source of yohimbine that also contains two other ingredients that will help you lose fat faster, preserve muscle, and maintain training intensity and mental sharpness, try Forge.
  • One serving of Phoenix per day. Phoenix is a 100% natural fat burner that speeds up your metabolism, enhances fat burning, and reduces hunger and cravings. You can also get Phoenix with caffeine or without.

(And again, if you’d like even more specific advice about which supplements you should take to reach your health and fitness goals, take the Legion Supplement Finder Quiz, and in less than a minute, you’ll know exactly what supplements are right for you. Click here to check it out.)

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FAQ #1: What do raspberry ketones do?

We don’t know.

Many people take raspberry ketones for weight loss because they believe doing so will enhance fat burning, limit fat gain, and decrease appetite.

There’s no evidence this is true in humans, though.

FAQ #2: Do raspberry ketones put you in ketosis?


Many people conflate the two because they sound similar, but raspberry ketones don’t trigger ketosis or support a keto diet.

FAQ #3: Should I believe the raspberry ketones before and after pictures online?

Probably not.

Most raspberry ketone before and after pictures are produced by supplement companies to sell their products, which means there’s a good chance the images have been doctored to appear more impressive than they are.

Or, they simply show people who lost weight following proven methods like calorie restriction, high-protein dieting, and strength training, and are attributing the benefits to raspberry ketones. 

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