Benefits
Appetite regulation and satiety
In a placebo-controlled trial in 54 overweight adults, 2 months of Metabolaid® raised the fullness hormone GLP-1 and lowered the hunger hormone ghrelin. In a crossover trial in 33 overweight adults, people felt fuller and ate about 75 fewer calories at a test meal (774 versus 850 kcal) after 2 months on the blend.
Body weight and fat mass reduction
In an 84-day placebo-controlled trial in 84 adults with a BMI of 25 to 35 on their usual diet, average weight fell from 87.4 to 86.2 kg with the blend and barely changed with placebo, and trunk fat fell. In a 2-month trial in 56 people on a balanced diet, waist size and body fat fell more than with placebo in the overweight group, with smaller changes in obese people.
Blood pressure support
In an 84-day placebo-controlled trial in 80 adults with high-normal or stage 1 high blood pressure, Metabolaid® lowered daytime blood pressure readings on 24-hour monitors, mostly systolic, by about 3%. Two weight trials also reported lower blood pressure or heart rate. The maker funded these trials or had staff among the authors.
AMPK and fat use in animal studies
In high-fat-fed mice, Metabolaid® reduced weight gain and fat tissue and raised AMPK activity and fat burning in the liver. In fat cells grown in a dish, the blend lowered fat content and raised AMPK activity. No human trial has measured AMPK or fat burning with this blend.
Mechanism of action
AMPK activation in cell and animal models
AMPK is an enzyme that helps cells switch between burning sugar and fat. The blend raised AMPK activity in mouse liver and in lab-grown fat cells. The human trial authors propose AMPK as a possible explanation, but none of them measured it in people.
Appetite hormone changes
In the 2-month trial in overweight adults, GLP-1 rose and ghrelin fell with the blend, and in the crossover trial leptin and GLP-1 shifted. These hormone changes are one proposed reason for the lower appetite ratings in the crossover trial.
Clinical trials
Randomized, double-blind, placebo-controlled trial; lemon verbena and hibiscus extract blend for 2 months (Boix-Castejón et al. 2018, Food Funct)
54 overweight adults
Body measurements, blood pressure, heart rate and overall health ratings improved, GLP-1 rose and ghrelin fell. The abstract does not give effect sizes.
Randomized, double-blind, placebo-controlled crossover trial; two 60-day periods separated by a 30-day washout (Serna et al. 2022, Eur J Nutr)
33 overweight or obese adults, average BMI 28.2
Appetite ratings were lower and the satiety quotient higher with the blend, and people ate 774 versus 850 kcal at an all-you-can-eat meal (p < 0.004). GLP-1 during the test meal was higher with the blend than with placebo, but GLP-1 in the blend period was lower at the end than at the start (4.34 to 3.23 ng/mL); leptin also changed. Funded by an EU research program, with maker staff credited for project administration and supplies.
Randomized, double-blind, placebo-controlled trial; 500 mg a day or placebo for 84 days (Marhuenda et al. 2020, Foods)
84 sedentary, healthy adults with BMI 25 to 35, 42 per group
Weight fell from 87.4 to 86.2 kg with the blend and from 87.5 to 87.3 kg with placebo (p = 0.014 between groups), BMI fell more than with placebo, and trunk fat fell. Blood lipids and glucose did not improve. Two authors worked for the maker.
Randomized, double-blind, placebo-controlled trial; 500 mg a day with an isocaloric diet for 2 months (Herranz-López et al. 2019, Sci Rep)
56 overweight or obese adults
In overweight participants, waist size fell 6.79 cm versus 1.85 cm with placebo and body fat 1.33% versus 0.66%, and heart rate and systolic blood pressure improved. Changes were smaller in obese participants. Partly funded by the maker.
Randomized, double-blind, placebo-controlled trial; 500 mg a day or placebo for 84 days with 24-hour ambulatory monitoring (Marhuenda et al. 2021, Molecules)
80 sedentary adults with high-normal or stage 1 high blood pressure
Daytime blood pressure readings fell with the blend but not with placebo, most clearly systolic pressure, which dropped about 3%. Funded by the maker and an EU research program.