Amarasate is a purified extract from bitter hop flowers grown in New Zealand that has been shown in previous clinical studies to increase production of endogenous glucagon-like peptide-1 (GLP-1), cholecystokinin (CCK) and peptide tyrosine tyrosine (PYY) by 6.4, 6.0, and 1.7 times baseline, respectively.[1] These three hormones are released from enteroendocrine L-cells lining the gut, when bitter taste receptors (TAS2Rs) on their apical surface are activated by the bitter Amarasate. The subsequent increase in these gut hormones was associated with the participants consuming 18% fewer calories. In two separate 24-hour fasting studies, Amarasate use at hours 16 and 20 led to a 25% decrease in overall hunger in men, a 30% and 40% decrease in overall hunger and cravings in women, and a 14% decrease in calories consumed at the fast-breaking meal in women.[2],[3]
As a result of these first three clinical studies, Amarasate has been sold as the bioceutical Calocurb®, delayed release capsules designed to help with weight management and available for over 5 years in New Zealand and 3 years in the United States. Over that time, there have been numerous anecdotal reports and case histories of the beneficial effects users have experienced from taking Calocurb, but the question has remained about how effective it's proven to be with long-term use. The results of a recently published study have answered that question.
-4.3%
Mean body weight reduction in the Calocurb group over 24 weeks (vs. -0.5% placebo)
-32.5 cm²
Mean reduction in visceral fat area (vs. -9.1 cm² placebo)
+0.9 kg
Mean gain in muscle mass in the Calocurb group — preserved throughout
The Amarasate Weight Loss and Body Composition Study
In 2025, a six-month weight loss study was conducted in New Zealand in which 150 overweight or obese adults were randomized to receive either Calocurb or placebo in a double-blind parallel design, to compare its effectiveness in aiding weight loss (the primary endpoint).[4] Changes in body composition were also assessed. The participants were aged 18–45 years, with BMIs of 25–35 kg/m² and were excluded if they were currently taking weight loss medications, actively engaged in a weight loss program, had recently lost or gained 5kg weight, had a history of gastrointestinal disease, or were diabetic. Patients in the active arm received Calocurb 125 mg capsules, which was titrated up over three weeks to a maximum dose of 500 mg /day, taken as two capsules an hour before the two main meals of the day on an empty stomach. Every four weeks, all participants were seen for body weight and composition measurements (via the InBody S10 analyzer) and attended group seminars for lifestyle (diet and exercise) advice. Blood draws were taken prior to the beginning and end of the study for renal and liver function measurements, along with lipid profiles and HbA1c levels.
Results
Of the 150 participants, ~75% were female; the mean values for age, weight and BMI were 35 years, 85.8 kg, and 30 kg/m², respectively.[4] In total, 128 people completed the study (65 in the Calocurb group and 63 in the placebo group). One person from each arm left the study due to capsule side effects. Reduced treatment tolerability led to one person in the placebo arm taking half the study dose; in the active arm, five did so, while another took a quarter of the dose. In general, however, the dose was well tolerated, and most participants achieved the full dose after titration.
The primary and secondary endpoints at week 24 are summarized in Table 1. For all but the change in muscle mass, the differences from baseline to week 24 were significant in the treatment group but not the placebo group. In addition, the treatment group changes were significantly greater than those in the placebo group (except for the change in muscle mass). Figure 1 shows the results over time.
Table 1: Mean changes in body weight and composition: Calocurb vs. placebo, at 24 weeks.[4]
| Parameter | Calocurb (n=65) | Placebo (n=63) |
|---|---|---|
| Change in body weight (kg) | -3.8 | -0.4 |
| Change in body weight (%) | -4.3 | -0.5 |
| Change in fat mass (kg) | -4.5 | -0.7 |
| Change in visceral fat area (cm²) | -32.5 | -9.1 |
| Change in muscle mass (kg) | +0.9* | +0.2 |
| Change in muscle mass-adjusted body weight (%) | -5.3 | -0.7 |
*All between group differences were significant (p<0.05) except for the change in muscle mass, which was not significantly different.
Figure 1: Mean changes (Δ) in primary and secondary endpoints weeks 0–24, Calocurb vs. Placebo[4]
A: Muscle mass-adjusted body weight (%)
B: Fat mass (kg)
C: Visceral fat area (cm²)
D: Muscle mass (kg)
Discussion
Weight loss in the Calocurb group occurred steadily over the study period, culminating in a mean loss of 3.8 kg (4.3%).[4] In contrast, the placebo group participants initially dropped their weight for the first 12 weeks, but then regained it to within 0.5 kg of their baseline weight — as expected in the study design that mimicked a real world situation (with minimal dietary and exercise advice). This trend was repeated for fat mass and visceral fat values. Importantly — and in contrast to studies of prescription medications for weight loss — muscle mass was not only preserved but increased by almost a kilogram in the treatment group. Indeed, the total fat loss was 5.3% in the Calocurb group after adjusting for the gain in muscle mass (vs. 0.7% for the placebo group).[4]
Compared to real-world weight loss achieved with GLP-1 RAs after six months' use, Calocurb shows an effect that is close to that of liraglutide (5%)[5], almost half that of semaglutide (11%)[6], and a third that of tirzepatide (13%)[7]. Calocurb's weight loss is noteworthy, not only because it's an over-the-counter bioceutical rather than a prescription pharmaceutical, but also because it occurred while maintaining muscle mass.
Conclusion
For those practitioners who have been awaiting proof of Calocurb's efficacy in aiding weight loss in a real-world situation, this 6-month study has demonstrated it not only significantly reduces body mass compared to placebo (and baseline) but targets fat loss — especially visceral fat — and preserves muscle. Available as 125 mg or 250 mg capsules, Calocurb is a valuable and effective addition to (minimal) dietary and exercise advice that mimics real-world weight management programs.
