Benefits
Resting energy expenditure after a single dose
In an open-label crossover study in 40 healthy adults, run with scientists from the maker and published as a conference abstract, one 100 mg dose raised resting energy expenditure about 6% compared with placebo, which trade press reports as roughly 100 extra calories a day. It was a single-dose measurement and has not been published as a full peer-reviewed paper.
Fat breakdown markers around exercise
In a randomized crossover trial in 20 healthy adults, partly funded by the maker, blood free fatty acids and glycerol, markers of fat breakdown, did not differ overall from placebo, but their percent rise from baseline was larger after a single 2 mg capsaicinoid dose at some time points around a 30-minute workout. Adrenaline, noradrenaline, heart rate and blood pressure did not differ from placebo.
Body composition over 12 weeks
In a 12-week placebo-controlled trial in 77 overweight adults, neither 2 nor 4 mg a day significantly changed body composition measured by DEXA, though waist-to-hip ratio fell in the 2 mg group at 6 weeks. A later post hoc analysis that adjusted for diet and body build found less body fat and fat mass at 4 mg than placebo.
Appetite and calorie intake
In the 12-week trial, people taking 4 mg a day reported eating about 257 fewer calories a day than the placebo group by week 12, based on their own intake reports. A pooled analysis of capsaicinoid studies, mostly not using Capsimax, found about 74 fewer calories eaten at a meal after a dose, with widely varying results.
Mechanism of action
TRPV1 receptor activation
Capsaicinoids bind TRPV1, the heat-sensing receptor behind the burn of chili peppers. A systematic review describes this receptor as widely accepted to drive much of capsaicinoids' effects on energy use, fat burning and appetite, though the full mechanism is not settled.
Fat breakdown without an adrenaline rise
With Capsimax, the percent rise in blood free fatty acids and glycerol was larger than with placebo at some time points after a dose, but adrenaline and noradrenaline did not differ from placebo. So the small rise in fat breakdown markers seen in that trial was not explained by a measurable stress hormone surge.
Coated beadlet delivery
Capsimax places the capsicum extract in a coated beadlet to reduce the burning feel of hot pepper. In a small tolerability study, doses up to 10 mg capsaicinoids a day were tolerated, but 23% of people starting 4 mg a day in the 12-week trial reported stomach upset.
Clinical trials
Randomized, double-blind, placebo-controlled trial; 2 mg or 4 mg capsaicinoids a day from Capsimax or placebo for 12 weeks (Urbina et al. 2017, Appetite)
77 healthy overweight adults, average BMI 27.5
Neither dose significantly changed body composition by DEXA. Waist-to-hip ratio fell in the 2 mg group by week 6. The 4 mg group reported eating 257 fewer calories a day than placebo at week 12. 23% of those starting 4 mg reported stomach upset, and the 4 mg group had a rise in fasting insulin and a fall in HDL cholesterol.
Post hoc analysis of a randomized, double-blind, placebo-controlled exploratory study, adjusting for lean mass, fat mass, diet and cholesterol; placebo, 2 mg or 4 mg capsaicinoids for 12 weeks (Rogers et al. 2018, BMC Obes)
75 healthy men and women aged 18 to 56
After statistical adjustment, percent change in body fat was 5.91 percentage units lower and change in fat mass 6.68 units lower at 4 mg than placebo (p = 0.040 and 0.049). One author worked for the maker and another consulted for it. The maker funded the analysis.
Randomized, placebo-controlled, double-blind crossover trial; single 2 mg capsaicinoid Capsimax dose or placebo, with 30 minutes of exercise (Bloomer et al. 2010, Lipids Health Dis)
20 healthy adults
Blood free fatty acids, glycerol, adrenaline and noradrenaline did not differ overall from placebo. In percent change from baseline, free fatty acids were higher than placebo at 2 and 2.5 hours and glycerol at 4 hours. Heart rate and blood pressure did not differ. Partly funded by the maker.
Open-label, placebo-controlled acute crossover study with a portable metabolic device; single 100 mg Capsimax dose (Deng et al. 2017, Adv Nutr)
40 healthy adults, average age 28
Resting energy expenditure was about 6% higher than with placebo, with no difference in heart rate or blood pressure, according to a trade press report of this conference abstract. Scientists from the maker ran the study with Arizona State University.