Dr. Oz recently gave some air time to a supplement called Raspberry Ketone (RK), promoting it as an effective agent for aiding weight loss. The segment of the show was titled “Miracle Fat-Burner in a Bottle“. Search around the internet and you’ll find plenty of sites hyping the product. Let’s find out what the scientific evidence says about RK.

First, let me point out that fat loss expert Lisa Lynn says, when asked how she found out about raspberry ketone, “Research, research, research.” Not so fast, Lisa! I can find only 3 papers specific to raspberry ketone: 1 study performed on mice (Morimoto), 1 paper regarding RK’s effects on lipolysis through modulation of adiponectin (Park), and 1 abstract from a presentation given regarding RK’s effects on rats (Wang). Human studies? Not one. Proof that raspberry ketone is a safe, effective fat burner? Not a chance!

Now, since I pride myself on being impartial and giving fair reviews of weight loss products, I will say that the evidence so far is intriguing. This compound should definitely be put through rigorous scientific testing to assure its safety and efficacy. Then, and only then, should it be recommended by the likes of Dr. Oz and Miss Lynn.

The Evidence


First, let’s discuss the Morimoto study. They fed mice a diet high in fat (beef tallow) in an effort to induce obesity. It worked – the mice gained weight. They also gave groups of mice varying amounts of RK. The group given the highest level of RK gained less weight than mice given the fat-inducing diet only. This isn’t exactly a weight loss study – it’s more like a weight gain study. The researchers also determined that RK reduced absorption of dietary fat in the small intestine through a blunted pancreatic lipase activity. This could mean the wonderful fat-blocker side effect: loose stool (what aisle are the adult diapers in).

One more thing about the Morimoto study: they never, ever say how much RK they gave the mice, except as a percentage of food weight. The mice were fed RK as .5, 1 or 2% gram weight of the diet and we’re never told how many grams of food/day the mice eat, so we don’t know how much RK they consumed. We might be able to figure it out, though. The weight-inducing food breaks down like this:

beef tallow 40%, casein 34–36%, corn starch 10%, sugar 9%, vitamin mixture (AIN-93G) 1% and mineral mixture (AIN-93G) 4% (w/w per 100 g diet)

In other words, for the ingredients that will yield energy content: 40 grams beef tallow (360 calories), 35 grams casein (140), 10 grams corn starch (40 calorie), 9 grams sugar (36 calories). This totals 576 calories for every 100 grams. Stay with me, this math gets fun in a second.

The researchers tell us the mice fed the high-fat diet ate about 800 KJ per week, or about 191 calories. This is about 1/3 of the 100 gram mixture we saw up above, which means the 2% RK group ate about .6 grams of RK/week, or 86 mg/day. The 1% group consumed about half that, or .3 grams/week or 42 mg/day. This is for a 35 gram animal. This means for a human who weighs about 155 lbs (70 kg), a dose of 17.2 grams/day for the 2% group or 8.5 grams/day for the 1% group. On Dr. Oz, Lisa recommends a couple hundred milligrams/day. Not even close to the effective dose used on mice in the Morimoto study. Apparently, neither Dr. Oz or Lisa Lynn can do simple math.

At a typical dose of 150 mg per capsule, you’d be consuming 57 capsules/day to reach the smaller effective dose of the Morimoto mice . Do you think this sounds like fun? Me neither. And at $15/bottle with 180 capsules in each bottle, you’re talking about spending  $142.50 every 30 days. You’ve been meaning to cancel your cable and cell phone service anyway, right?


The Wang presentation is unavailable to me in full text, but they also used .5, 1 and 2% dosages, this time in rats. The same argument applies.


The Park paper gives us insight into the possible mechanisms by which RK might elicit its fat-burning effect. This means nothing until it’s shown to be effective in humans at a tolerable, safe dose.

How is it that a health professional like Dr Oz, along with his staff and probably a few bucks, end up giving such high praise to this supplement? “Miracle Fat Burner” Really!? At this time it is clear, from the evidence, that RK is NOT a useful weight loss supplement.



Morimoto, C., Satoh, Y., Hara, M., Inoue, S., Tsujita, T., & Okuda, H. (2005). Anti-obese action of raspberry ketone. Life sciences, 77(2), 194-204. doi:10.1016/j.lfs.2004.12.029

Park KS. Raspberry ketone increases both lipolysis and fatty acid oxidation in 3T3-L1 adipocytes. Planta Med. 2010 Oct:76(15):1654-8. Epub 2010 Apr 27

Schoeneberger MS, Thiboutot JR. Nobody ever reads references: If you see this, email us to receive 10 SPEED bonus points. Int J of SPEED. 89(2) 101-1001. 

Wang Lili, Meng Xianjun, Zhang Yan, Zhao Wei. Experimental study on the mechanism of raspberry ketone on simple obesity and insulin resistance relevant to obesity. http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=6027896


Raspberry Ketone for Weight Loss: A Review
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