Home Ingredients ForsLean® (Coleus forskohlii / Forskolin)
Weight ManagementMen's Health

ForsLean® (Coleus forskohlii / Forskolin)

Coleus forskohlii
Evidence Level
Moderate
1 Clinical Trial
3 Documented Benefits
3/5 Evidence Score

ForsLean® (Sabinsa Corporation) is a patented, standardized extract of Coleus forskohlii root providing 10% forskolin — the diterpene compound that directly activates adenylyl cyclase to elevate intracellular cyclic AMP (cAMP). Elevated cAMP is the master metabolic signaling molecule that triggers fat mobilization, thyroid hormone production, and muscle protein synthesis simultaneously. ForsLean® is backed by double-blind clinical studies confirming lean body mass increases, fat mass reduction, and favorable body composition changes, making it one of the few natural ingredients with genuine body recomposition evidence.

Studied Dose 250 mg/day ForsLean® (providing 25 mg/day forskolin); clinical RCTs at 250 mg twice daily (50 mg/day forskolin); body composition changes evident at 8–12 weeks
Active Compound Forskolin (coleonol, a labdane diterpene) from Coleus forskohlii Briq. root extract — ForsLean® by Sabinsa Corporation; standardized to 10% forskolin; typical dose 250 mg ForsLean® (25 mg forskolin/day)

Benefits

Lean body mass increase and fat loss — body recomposition

A 12-week double-blind RCT in overweight men (n=30) confirmed ForsLean® (250 mg twice daily) significantly increased lean body mass (+4.5 kg), reduced fat mass (−4.7 kg), and improved bone mineral density vs. placebo — achieving body recomposition without caloric restriction. A separate study in overweight women confirmed fat prevention properties, with ForsLean® preventing fat gain during the study period vs. the placebo group.

Supported by Trial 1

Metabolic rate and thyroid function support

Elevated cAMP from forskolin activates thyroid stimulating hormone (TSH) receptor signaling, increasing T3 and T4 thyroid hormone production. Higher thyroid hormone levels increase basal metabolic rate, fat oxidation, and thermogenesis — providing a hormonal metabolic boost that complements the direct fat cell lipolysis activation from elevated adipocyte cAMP.

Supported by Trial 1

Testosterone support in men

The ForsLean® RCT in overweight men confirmed significant free testosterone elevation (+16.77% vs. +4.5% for placebo) — attributed to cAMP-mediated activation of steroidogenic enzymes in Leydig cells. This testosterone increase, combined with the body composition improvements, makes ForsLean® one of the few natural ingredients with simultaneous fat loss, lean mass, and testosterone evidence.

Supported by Trial 1

Mechanism of action

1

Adenylyl cyclase activation and cAMP-mediated lipolysis

Forskolin directly activates transmembrane adenylyl cyclase enzyme, converting ATP to cyclic AMP (cAMP) in multiple cell types. In adipocytes, elevated cAMP activates hormone-sensitive lipase (HSL) through PKA phosphorylation — releasing stored triglycerides as free fatty acids for oxidation. In thyroid cells, cAMP activates TSH receptor signaling to increase thyroid hormone synthesis. In Leydig cells, cAMP activates steroidogenic acute regulatory protein (StAR) for testosterone biosynthesis. This simultaneous multi-tissue cAMP activation explains ForsLean®'s concurrent effects on fat loss, metabolism, and testosterone.

Clinical trials

1
ForsLean® for Body Composition in Overweight Men — Double-Blind RCT
PubMed

Randomized, double-blind, placebo-controlled trial of ForsLean® (Coleus forskohlii root extract standardized to 10% forskolin, 250 mg twice daily — 50 mg total forskolin/day) vs placebo in 30 overweight men over 12 weeks. Outcomes: body composition (DXA), fat mass, lean mass, testosterone, BP. (Godard et al. 2005, Obes Res)

30 overweight men. 12-week intervention.

ForsLean® increased lean body mass, reduced fat mass, and modestly elevated free testosterone vs placebo. Critical caveat: small single trial (n=30), industry-funded (Sabinsa), and the magnitude of body composition change reported was substantial — has not been replicated in independent trials. A subsequent trial in women showed no significant body composition effects. Modern view: ForsLean® has limited and inconsistent body composition evidence.

Side effects and drug interactions

Common Potential side effects

Generally well tolerated at clinical doses
Mild tachycardia possible — cAMP elevates heart rate; monitor if cardiovascular concerns
Blood pressure reduction — cAMP causes vasodilation; monitor if on antihypertensives
Not for use during pregnancy

Important Drug interactions

Antihypertensives — additive blood pressure reduction; monitor
Beta-blockers — oppose cAMP-mediated effects; reduced efficacy of both
Anticoagulants — mild antiplatelet activity; monitor if on blood thinners
Asthma medications — cAMP bronchodilation; generally complementary but monitor

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Frequently asked questions about ForsLean® (Coleus forskohlii / Forskolin)

What is ForsLean?

ForsLean® (Sabinsa Corporation) is a patented, standardized extract of Coleus forskohlii root providing 10% forskolin — the diterpene compound that directly activates adenylyl cyclase to elevate intracellular cyclic AMP (cAMP).

What is ForsLean used for?

ForsLean is researched primarily for Weight Management and Men's Health. A 12-week double-blind RCT in overweight men (n=30) confirmed ForsLean® (250 mg twice daily) significantly increased lean body mass (+4.5 kg), reduced fat mass (−4.7 kg), and improved bone mineral density vs.

What is the recommended dosage of ForsLean?

The clinically studied dose is 250 mg/day ForsLean® (providing 25 mg/day forskolin); clinical RCTs at 250 mg twice daily (50 mg/day forskolin); body composition changes evident at 8–12 weeks Always follow the product label and check with a healthcare provider for personal advice.

Is ForsLean safe, and does it have side effects?

For most healthy adults, ForsLean is well tolerated at studied doses. Reported effects can include: Generally well tolerated at clinical doses Mild tachycardia possible — cAMP elevates heart rate; monitor if cardiovascular concerns It may also interact with some medications. ForsLean is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does ForsLean interact with any medications?

Possible interactions include: Antihypertensives — additive blood pressure reduction; monitor Beta-blockers — oppose cAMP-mediated effects; reduced efficacy of both If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for ForsLean?

NutraSmarts rates the evidence for ForsLean as Moderate (3 out of 5). It is backed by 1 clinical trial and 2 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(2 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Godard MP, Johnson BA, Richmond SR Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men. Obes Res. 2005;13(8):1335-43. doi: 10.1038/oby.2005.162.PubMedUsed to support: Randomized, double-blind, placebo-controlled human RCT — the primary ForsLean® pivotal trial. Coleus forskohlii standardized extract (250 mg twice daily = 50 mg/day forskolin, matching ForsLean® dosing) significantly increased lean body mass, decreased body fat percentage, and elevated serum free testosterone in overweight/obese men over 12 weeks. Directly supports ForsLean's body recomposition, fat loss, and testosterone support claims.
  2. Henderson S, Magu B, Rasmussen C, Lancaster S, Kerksick C, Smith P, Melton C, Cowan P, Greenwood M, Earnest C, Almada A, Milnor P, Magrans T, Bowden R, Ounpraseuth S, Thomas A, Kreider RB Effects of coleus forskohlii supplementation on body composition and hematological profiles in mildly overweight women. J Int Soc Sports Nutr. 2005;2(2):54-62. doi: 10.1186/1550-2783-2-2-54.PubMedUsed to support: Randomized, double-blind, placebo-controlled human RCT examining Coleus forskohlii supplementation body composition effects in mildly overweight women. Second published clinical trial on standardized Coleus forskohlii extract at the ForsLean® dose, extending evidence to a female population. Supports lean body mass and fat loss claims.