Dr. Oz doesn't know it but he’s responsible for a lot of the emails I get. For example, in a recent segment of the Dr Oz Show, an herb called Coleus forskohlii (also called forskolin) was said to be one of the secrets to weight loss. I first reviewed Coleus forskohlii in my book a few years ago, but in case you missed that chapter, let’s take a look at this herb and see if I can help you make sense of it. Does it help people lose weight? Let's look at the research and see what we can discover.
What is Coleus Forskohlii?
Coleus forskohlii, is a member of the mint family of herbs. Its technical name is Plectranthus barbatus. The roots of the plant contain a compound called forskolin. As such, coleus forskohlii and forskolin are often used interchangeably. Traditionally used in Ayurvedic medicine to treat asthma and other ailments, for the last several years, it’s the claims that forskolin helps weight loss that has sparked peoples interest the most. I've even seen Dr. Oz say “it works” when talking about forskoiln
Supplement Tip. There are many weight loss supplements that contain Coleus forskohlii. My rule of thumb is that any supplement that contains the prefix “fors” or forsk” (or something similar) in their name, probably contains coleus forskohlii.
Coleus forskohlii has been in some products I've reviewed on this site. Some of those have included
Among others. See those reviews for additional information.
Coleus Forskohlii And Weight Loss
How does Coleus forskohlii help weight loss? Or rather, what is the theory behind how it’s supposed to work? This will get a little technical but bear with me, I promise to bring it home at the end.
Coleus forskohlii stimulates the production of a molecule called cyclic AMP (cAMP). In our body, cyclic AMP helps our cells talk to each other. When an increase or decrease in cAMP is detected, it acts as a signal that causes the body to do something.
One of the things that cAMP does is tell our cells to increase in an enzyme called hormone sensitive lipase—which burns fat. cAMP might also seems to stimulate the release of thyroid hormone which also helps burn fat and calories.
Translation: Coleus forskohlii (Forskolin) stimulates fat-burning enzymes and hormones which, in turn, causes weight loss.
The theory sounds good but is there any proof? It turns out there are a couple of Coleus forskohlii weight loss studies. Let’s take a look at them now.
Coleus Forskohlii Weight Loss Research
One study from 2005, titled Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men was published in the journal, Obesity Research.
This study looked at 30 overweight and obese men. Half of these men received Coleus forskohlii and half received a placebo. The people in this study took 250 mg of a supplement – called Called ForsLean – that had 10 % Coleus forskohlii. They took the supplement twice a day (so 500 mg total per day). The study lasted 12 weeks.
ForceLean is a patented extract from the Sabinsa Corporation. It's in many coleus forskohlii products.
Body fat was determined via DEXA, a very accurate body fat measurement technique that uses x rays.
Those people getting Coleus forskohlii showed a reduction in body fat as well as an increase in testosterone.
Lean body mass (I take this to mean muscle) increased as well– but lean body mass also increased in the placebo group too. This could be a
problem with the study.
While lean body mass did increase more in those getting the Coleus forskohlii extract, how did the placebo (which should, in theory, do nothing) also increase lean body mass? This is a problem. The people in this study did not exercise. So if exercise didn’t cause the increase in lean body mass what did?
Another problem is that the people in the Coleus forskohlii group had higher testosterone levels at the start of the study than those in the placebo group. If the people were randomly divided into two groups, one would think that testosterone levels would be pretty much the same between the groups. But they were not.
This doesn't make sense.
As such, I'm not sure if coleus forskohlii raises testosterone or not.
Another observation was that Coleus forskohlii did not increase metabolic rate. This contracts “experts” on the Dr Oz Show who have said that forskolin raises metabolic rate.
This particular study gets mentioned a lot on bodybuilding websites, however given the problems I just listed, I’d like to see another study to confirm these findings.
Another study, titled Effects of coleus forskohlii supplementation on body composition and hematological profiles in mildly overweight women was published in 2005 in the International Journal of the Society of Sports Nutrition.
In this study, 19 women were either given a Coleus forskohlii supplement – called ForsLean – which contained 250 mg of a 10% Coleus forskohlii extract. The supplement was taken twice a day (so, 500 mg total per day was taken). The other group received a placebo and the study lasted 12 weeks.
Body fat was determined via DEXA scan which is a good indicator of body composition.
This study found that Coleus forskohlii did not promote any significant weight loss but it did seem to reduce the gaining of weight.
The forskolin extract did not seem to change thyroid hormone, liver enzymes, cholesterol, insulin, heart rate, blood pressure or red or white blood cells. This study unfortunately did not measure testosterone levels as the study above did.
So, while the Coleus forskohlii extract didn’t seem to help weight loss, it did appear to help people from gaining weight.
It is interesting that supplement used in this study (ForsLean) is the same as that tested in the previous study. So, two studies on the same supplement each finding different outcomes.
These two human studies of Coleus forskohlii and weight loss appear to contradict each other in terms of whether Coleus forskohlii helps weight loss or not.
Based on this, maybe forskolin helps weight loss or maybe it might reduce the rate at which people gain weight. So which is it? I don’t think anyone has the answer at this time. This is a far cry from the proclamation of Dr Oz who said on his TV show “it works”.
In a 2014 study coleus forskholii was shown to curb appetite in rats fed a “cafeteria diet (basically they fed rats a lot of junk food). That's interesting and in theory, by curbing appetite, it might reduce gaining weight, which the previous study mentioned above noted. Still, this should be shown in human studies to know better what's going on.
Which Coleus Forskohlii Supplement Is Best?
There are a LOT of coleus forskohlii supplements out there. As such finding what may be the “best” can be daunting. So let me see if I can make the process a wee bit easier for you.
Some products make vague claims such as “raising metabolism” or boosting testosterone levels. But, from this review, claims like these are on shaky ground. As such, I recommend avoiding products that make claims like these.
Remember also that coleus forskohlii and forskolin refer to the same thing. Different supplement companies call it either names. Some brands may even call it by its scientific name: Plectranthus barbatus. This is important because this might confuse some people.
All that said, when I looked at the research, the brand I saw tested was called ForsLean.
Forslean is found in various coleus forskolii supplements either alone or in combination with other ingredients. That said, If coleus is going to work, I think the ForsLean supplement is the only ingredient that should be needed. In other words, there should be no need to combine coleus with garcinia cambogia, raspberry ketones or any other “popular” ingredients.
While studies often use 500 mg per day, given the lack of human research, its hard to know if this is the “correct” amount. As such, start with less to see if that works with you.
Coleus Forskohlii Side Effects
Based on the human studies done so far, Coleus forskohlii (forskolin) seems to be pretty safe in healthy people for at least 3 months. Some research studies using mice has noted that coleus forskholii might alter an enzyme system called P450 which is involved in metabolizing a variety of medications. Because of this, people who take any medications should ask their pharmacist or doctor and specially ask questions relating to the P450 enzyme system. Your doctor /pharmacist will know exactly what you are talking about when you say “P450 enzyme.”
So far, there is no research on people who are not “healthy” and the herb may interact with medications like blood thinners. People with serious health issues like heart disease etc. should speak to their doctor before taking Coleus forskohlii.
Stop all supplements at least 2 weeks before surgery.
I'm not aware of any research on coleus forskohlii and pregnancy or breast feeding so avoid it during these times also. When in doubt, ask your doctor first if you have any health issues.
Does Coleus Forskohlii Work?
Despite the hype, I feel more research is needed to know if coleus forskohlii (forskolin) really works or not. As more research is done, we will have a better if it works. As I have tried to show here, the research on forskolin is interesting but it is far from conclusive. I do think coleus forskohlii is an interesting supplement but I can't yet say either way whether it helps people lose weight or not because I want to see a few more human studies. If you have tried it and its helped you or not, I hope you will leave a comment below. On my personal website, I've written more about weight loss supplements that have evidence, along with other ideas that can help too.