Researchers at herbal extract manufacturer Star Hi Herbs and Adichunchanagiri Hospital and Research Centre in India assessed the anti-obesity effects of a Coleus forskohlii extract marketed as Forcslim.
They observed reductions of 1.83cm in waist circumference and 1.93 kg in body weight and improvements in lipid profiles in overweight subjects who took the supplement for 12 weeks.
“These findings suggest that C. forskohlii extract supplementation may serve as a safe and effective alternative to synthetic anti-obesity drugs,” they wrote in the Journal of the International Society of Sports Nutrition.
cAMP activation
C. forskohlii is part of the mint family and has a long history of use in Ayurvedic medicine. The plant’s main bioactive compound is forskolin, which can increase the intracellular messenger cyclic adenosine monophosphate (cAMP).
cAMP activates pathways that accelerate fat breakdown, energy release, and thermogenesis, enabling fat to be burned as energy and acting as a cellular on-switch for fat metabolism.
According to a 2025 review of Coleus forskohlii’s role in weight management, preclinical obesity models suggest that it reduces weight, adiposity, and dyslipidemia, and clinical trials point to its potential to prevent weight gain and improve body composition.
Higher levels of cAMP drive lipolysis (fat breakdown), and the released fatty acids also increase thermogenesis and lean tissue mass.
“Overall, forskolin may have the potential to reduce fat without reducing muscle mass,” the study noted.
Study details
The study was a quasi-randomized, double-blind, placebo-controlled trial conducted in 60 overweight adults aged 20 to 70 over 12 weeks. The researchers allocated them to two daily capsules of either Forcslim (250 mg of 10% ethanolic Coleus forskohlii extract per capsule) or placebo. The participants maintained their usual diet and physical activity throughout the trial and completed a food intake diary. The researchers assessed anthropometrics, biochemical parameters, and appetite at the start of the study and at weeks 4, 8 and 12.
Compared with placebo, the researchers observed a significant 1.8 cm reduction in waist circumference in the supplement group after the study, which they noted was clinically significant. The experimental group also showed a 1.93 kg reduction in body weight.
There was also a significant reduction in triglyceride levels and an increase in high-density lipoprotein (HDL) levels. Analysis of metabolic and physiological markers indicated a favorable safety profile.
The researchers acknowledged the study limitations, such as small sample size. They recommended larger follow-up trials over longer periods to understand the mechanisms and long-term effects of the herbal supplement.
Source: Journal of the International Society of Sports Nutrition; doi: 10.1080/15502783.2026.2725137; “A 12-week, double-blind, quasi-randomized, placebo-controlled study to evaluate the efficacy and safety of Coleus forskohlii (Forcslim) on body weight loss.” Authors: Channangihalli Thimmegowda, S., et al.
