Forskolin
Forskolin, labdane diterpene from Coleus forskohlii
Written by Aaron CuhaReviewed Sep 2026
Also known as: Coleonol, Coleus forskohlii extract, ForsLean
No lifespan benefit in either sex in the 2021 mouse cohort where epicatechin, halofuginone and mitoglitazone all extended male lifespan. The human evidence is two 12-week trials totalling 53 people, one showing fat loss in men and one showing none in women.
Overview
Forskolin is a diterpene from the root of Coleus forskohlii, and it is a genuinely important laboratory reagent: it activates adenylyl cyclase directly, bypassing G protein-coupled receptors, which makes it the standard tool for raising cyclic AMP in a cell. That pharmacological reliability is a large part of why it was worth testing and a large part of why it is oversold.
The Interventions Testing Program tested it in mice born in 2021, fed from 7 months of age, alongside 2BAct, dichloroacetate, epicatechin, halofuginone and mitoglitazone. Three of those six worked in males: epicatechin raised median lifespan by about 5 percent, halofuginone and mitoglitazone by about 9 percent each, with epicatechin and halofuginone also raising 90 percent survival. Forskolin was not among them. The report notes that this cohort continues the strong male bias seen across the programme's positives.
The human record is two small trials of a standardised 10 percent extract. In 30 overweight and obese men over 12 weeks, forskolin significantly reduced body fat percentage and fat mass on DXA against placebo, increased bone mass, and raised serum free testosterone. In 23 mildly overweight women on the same protocol, the same product did not promote weight loss; it produced non-significant trends toward mitigating weight gain, with no significant differences in fat mass, fat-free mass or body fat percentage, and the treated group reported less hunger.
That is a positive trial in 15 treated men and a negative trial in 7 treated women, which is the honest summary of the human evidence for one of the most heavily marketed fat-loss supplements.
Mechanism of action
A labdane diterpene that binds and activates adenylyl cyclase directly at the catalytic subunit, raising intracellular cyclic AMP without needing a receptor. Elevated cAMP activates protein kinase A, which phosphorylates hormone-sensitive lipase and perilipin and therefore promotes lipolysis in adipocytes, which is the entire basis of the fat-loss claim. cAMP also sits upstream of CREB-dependent transcription and of thyroid and steroidogenic signalling, which is the proposed route to the testosterone finding. The problem for oral use is that a compound which raises cAMP in every cell it reaches has no tissue selectivity, and oral bioavailability of the extract is poor enough that systemic exposure from a capsule cannot be assumed to resemble a cell culture experiment.
Human evidence
Two randomised 12-week trials from 2005 totalling 53 participants, one positive in men and one negative in women. Nothing since at any scale, and nothing on ageing.
- 30 overweight and obese men, 12 weeks: significant reductions in body fat percentage and fat mass on DXA, and a significant rise in serum free testosterone.
- 23 mildly overweight women, 12 weeks, same product and dose: no significant change in fat mass, fat-free mass or body fat percentage.
- The women's trial had 7 participants in the treatment arm, which is too few to detect anything but a large effect.
- Neither trial reported clinically significant changes in blood lipids, liver enzymes, thyroid hormones, heart rate or blood pressure.
- No human study has examined lifespan, healthspan or any geroscience endpoint.
What this does not tell you: Fifty-three people across two decades-old trials, with results that point in different directions in the two sexes, is not a basis for a confident claim about body composition. The testosterone finding comes from one arm of one trial of 15 men and has not been independently replicated. The mechanism is not in doubt, since forskolin raises cyclic AMP in any cell it reaches, but whether an oral capsule delivers enough to adipose tissue to matter has never been directly demonstrated in people.
Reading the research record
A lifespan null from this programme is a real, expensive, well-powered finding, and it is narrower than it sounds. What was tested was one concentration in the diet, started at one age, in one mouse strain, with death as the endpoint. A null tells you that this dose, in these animals, did not move that endpoint. It does not tell you the compound is inert, that a different dose would also fail, that the mechanism is wrong, or that the reason people actually take it has been refuted. Those are separate questions and most of them were never asked. The failure mode this site is trying to avoid runs in both directions: treating a mouse lifespan positive as proof that a supplement works, and treating a mouse lifespan null as proof that it does nothing.
Forskolin is worth having in this batch because its cohort makes the point better than any commentary could. Six compounds went into the 2021 mouse cohort. Three of them extended male lifespan by 5 to 9 percent. Forskolin did not. Same three laboratories, same strain, same diet-delivery method, same starting age, same statistical plan, published in the same paper.
That is what a properly controlled null looks like, and it is why the programme's negatives carry weight that a single-laboratory negative would not. The experiment demonstrably could detect an effect of the size being looked for, because in the next arm it did, three times.
What it still does not tell you is whether the thing people buy forskolin for works. That was tested in 53 people in 2005 and the answer came back positive in men and negative in women, and nobody has run a larger trial since.
The Interventions Testing Program is funded by the National Institute on Aging and run in parallel at three independent laboratories, in Bar Harbor, Ann Arbor and San Antonio. It uses UM-HET3 mice, a four-way genetic cross, so no result can be an artefact of a single inbred background. Both sexes are studied, cohorts are sized to detect roughly a 10 percent shift in lifespan, compounds are fed in the diet from a stated starting age, and the programme commits in advance to publishing negative results alongside positive ones. That last commitment is why this batch can exist at all: almost no other part of ageing research reliably tells you what did not work.
The evidence, charted
Fig. 1 · evidence composition
2of 3 citations (67%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Citations here span just two years, 2005 and 2026.
Too few distinct publication years on this page to plot as a timeline.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 4 · dose response
No human dose response curve exists
We draw this figure where the data supports it. For this compound in humans it does not, so the panel stays empty rather than borrowing an animal curve and implying it transfers.
Key studies & citations
- Animal2026
Extension of lifespan by epicatechin, halofuginone and mitoglitazone in male but not female genetically heterogeneous mice
Interventions Testing Program, mice bred in 2021, all agents fed in the diet from 7 months of age. The cohort tested 2BAct, dichloroacetate, epicatechin, forskolin, halofuginone and mitoglitazone. In males, epicatechin increased median lifespan by about 5 percent and halofuginone and mitoglitazone by about 9 percent each, with epicatechin and halofuginone also increasing 90 percent survival. Forskolin was not among the agents reported to extend lifespan. The authors note the report continues the strong male bias among the programme's positive findings.
GeroScience - Human2005
Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men
30 men with BMI at or above 26, randomised double-blind to 250 mg of a 10 percent forskolin extract twice daily or placebo for 12 weeks. Body fat percentage and fat mass on DXA fell significantly against placebo, bone mass changed significantly, serum free testosterone rose significantly, and lean body mass showed a non-significant trend upward (p equals 0.097). Fifteen participants per arm.
Obesity Research - Human2005
Effects of coleus forskohlii supplementation on body composition and hematological profiles in mildly overweight women
23 women randomised double-blind to 250 mg of a 10 percent Coleus forskohlii extract twice daily (n equals 7) or placebo (n equals 12) for 12 weeks. No significant differences in fat mass, fat-free mass or body fat percentage. Non-significant trends toward mitigating gains in body mass (p equals 0.10) and scanned mass (p equals 0.08). Treated participants reported less hunger and fullness. No clinically significant changes in blood lipids, liver or muscle enzymes, thyroid hormones, insulin, heart rate or blood pressure. The authors concluded it does not appear to promote weight loss but may help mitigate weight gain.
Journal of the International Society of Sports Nutrition
Frequently asked questions
Does forskolin burn fat?
It activates adenylyl cyclase and raises cyclic AMP, which does drive lipolysis in fat cells. In people, the evidence is two 12-week trials from 2005: 30 overweight men lost significant body fat against placebo, and 23 mildly overweight women showed no significant change. Nobody has run a larger trial since.
Does it raise testosterone?
One trial in 30 men reported a significant rise in serum free testosterone over 12 weeks, with total testosterone not significantly different between groups. Fifteen men on treatment, one study, never independently replicated. That is not enough to rely on.
Did it extend lifespan in mice?
No. It was fed from 7 months of age in the National Institute on Aging's 2021 cohort and was not among the compounds reported to extend lifespan. Three other compounds in the same cohort, epicatechin, halofuginone and mitoglitazone, extended male median lifespan by 5 to 9 percent, so the experiment was clearly able to detect effects of that size.
Why is forskolin so widely used in laboratories?
Because it activates adenylyl cyclase directly, without a receptor, which makes it the standard way to raise cyclic AMP in a cell for an experiment. That reliability in a dish is often presented as though it implied a reliable effect in a person, and it does not: an oral extract with poor bioavailability reaching every tissue at once is a different situation entirely.