Great question! Let me share what Pillser's research database shows about Coleus forskohlii (often standardized for its active compound forskolin).

What the Evidence Says

According to Pillser's research data, there is 1 study on coleus for reduced waist circumference, and it yielded a neutral result — meaning no statistically significant benefit was found¹.

Outcome	Studies	Beneficial	Neutral	Harmful
Reduced Waist Circumference	1	0	1	0

So, Is It Effective?

The short answer: Based on the available evidence in Pillser's database, coleus has not been shown to significantly reduce waist circumference. The single study on this outcome did not find a benefit.

That said, it's worth noting that some earlier small studies on Coleus forskohlii (forskolin) and body composition have been published in the broader literature — some suggesting modest effects on body fat, others showing no significant difference from placebo. The results have been mixed.

Was It Just a "Study Effect"?

The "study effect" you're referring to (people losing weight simply because they're enrolled in a study — due to increased attention, lifestyle tracking, or placebo effects) is a real phenomenon in clinical research. However, in the case of coleus for waist circumference, even that doesn't seem to apply here, as the one study on record was neutral — meaning participants didn't show significant waist reduction compared to controls.

Bottom Line

Current evidence from Pillser does not support coleus (Coleus forskohlii) as an effective supplement for reducing waist circumference¹. Other supplements like African mango, Lactobacillus gasseri BNR17, chia seed, and black cumin have more positive evidence for this outcome in Pillser's database.

Footnotes

1. Pillser research database, Coleus and Reduced Waist Circumference. ↩ ↩²