Yerba mate is an herb traditionally consumed in South America, where it’s known for its energy-boosting properties. In North America, Europe, and Asia Minor, its use as a tea is becoming increasingly common due to its antioxidant properties and effects on vasodilation. A recent Nutrition and Metabolism study investigated yerba mate’s fat-burning properties during exercise.
Many consumers use yerba mate to burn body fat. In addition to having many healthy ingredients, yerba mate also has caffeine levels comparable with tea. Caffeine is known to promote the burning of fat all on its own, so the practice is certainly reasonable.
However, until this study, there was no research that investigated the effects of yerba mate as a fat burner during exercise. While it may help to boost metabolism and thus increase fat burning while at rest, that doesn’t mean it will have the same effect during exercise. Because the use of fat for fuel during exercise is already heightened, it’s possible that yerba mate would simply have no effect at all when used during a workout.
In the study, a group of fourteen men and women were recruited to partake in two sessions on an exercise bike. Each time their test on the bike was the same and each time they received a pill one hour before cycling. The pills either contained one gram of yerba mate or a placebo. The pills were given in a random order. Half of the participants received the yerba mate first and the other half received the placebo first. The researchers switched the order during the second trial.
The participants rode on the bike at increasing intensities every three minutes until they reached the limits of their ability to intake oxygen. The researchers measured performance, drew blood to find metabolic waste products, and took breath samples to determine how much energy was consumed.
The power output and blood lactate content of each participant was statistically unchanged by taking the yerba mate pill, but energy expenditure increased. In fact, both fat burning and the percentage of total energy expenditure that came from fat instead of carbs or protein both increased by 24%, as long as the intensity levels were submaximal, or below seventy percent of VO2 peak. For most people, this intensity would be equivalent to a heart rate of between 150 and 160 beats per minute.
It’s likely the caffeine found in yerba mate played a major role here, but there are two things to consider. First, yerba mate has many other beneficial ingredients, and they may also work synergistically to create the observed effect.
Second, the participants were selected partly because they weren’t habitual caffeine users. In other words, they consumed less than an average of two small cups or one big cup of coffee a day. Habitual caffeine use can reduce the effect, so if you plan on reaping the benefits of yerba mate, don’t consume caffeine every day.
1. Ahmad Alkhatib, et. al., “Yerba Mate (Illex Paraguariensis) ingestion augments fat oxidation and energy expenditure during exercise at various submaximal intensities,” Nutrition and Metabolism 2014, 11:42
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