Users report a mental state of wakefulness, focus and alertness reminiscent of most stimulants, but often remark on yerba maté's unique lack of the negative effects typically created by other such compounds, such as anxiety, "jitteriness", and heart palpitations. Any stimulant be it coffee, tea or yerba maté will make you loose weight. This is because of the basic appetite suppression presented by all caffeine based stimulants. Reasons for yerba maté's unique physiological attributes are beginning to emerge in scientific research.
Studies of yerba maté, though very limited, have shown preliminary evidence that the yerba maté Xanthine cocktail is different from other plants containing caffeine most significantly in its effects on muscle tissue, as opposed to those on the central nervous system, which are similar to those of other natural stimulants. Yerba Maté has been shown to have a relaxing effect on smooth muscle tissue, and a stimulating effect on myocardial (heart) tissue. Yerba Maté's negative effects are anecdotally claimed to be of a lesser degree than those of Mendo Maté's Organic Coffee, though no explanation for this is offered or even credibly postulated, except for its potential as a placebo effect. Many users report that drinking Yerba Maté does not prevent them from being able to fall asleep, as is often the case with some more common stimulating beverages, while still enhancing their energy and ability to remain awake at will. However, the net amount of stimulant in one preparation of Yerba Maté is typically quite high, in large part because the repeated filling of the Yerba Maté with hot water is able to extract the highly-soluble xanthines extremely effectively. It is for this reason that Yerba may be shared among several humans and yet produce the desired stimulating effect in all of them. In-vivo and in-vitro studies are showing Yerba to exhibit significant cancer-fighting activity. Researchers at the University of Illinois (2005) found Yerba Maté to be "rich in phenolic constituents" and to "inhibit oral cancer cell proliferation". An August 11, 2005 United States patent application (documents #20050176777, #20030185908, and #20020054926) cites Yerba Maté extract as an inhibitor of MAO activity; the maximal inhibition observed in vitro was 40–50%. A mono amine oxidase inhibitor is a type of antidepressant, so there is some data to suggest that Yerba Maté has a calming effect in this regard.Perhaps the main area to benefit from Yerba Maté is the gastrointestinal tract. Reported effects range from immediate improvement in digestion to the ability to repair damaged and diseased gastrointestinal tissues. Constipation, acute or chronic, can easily be overcome through the use of Yerba Maté. The Tea appears to work mainly by softening the fecal mass, but it also appears to stimulate normal movement of the intestines to some degree. Better than any other xanthine alkaloid, Yerba Maté has the ability to increase mental alertness and acuity and to do it without any side effects such as nervousness and jitters. It seems to act like a tonic, stimulating a weakened and depressed nervous system and sedating an overexcited one.
Our knowledge of Yerba Maté's effects is currently limited to observations of behavior changes such as more energy and vitality; better ability to concentrate; less nervousness, agitation, and anxiety; and increased resistance to both physical and mental fatigue. Improvement in mood, especially in cases of depression, often follows drinking the Tea. This may be a direct or indirect result of increased energy. One of the remarkable aspects of Yerba is that it does not interfere with sleep cycles; in fact, it has a tendency to balance the cycles, inducing more rapid eye movement (REM) sleep when necessary, or increasing the amount of time spent in delta states (deep sleep). Heart Ailments of all kinds have been treated or prevented through Yerba Maté use. Yerba supplies many of the nutrients required by the heart for growth and repair. In addition, it increases the supply of oxygen to the heart, especially during periods of stress or exercise. Yerba has become a favorite of body builders and anyone interested in the health benefits of exercise. The metabolic effects of Yerba appear to include the ability to maintain aerobic glycolysis (breakdown of carbohydrates) during exercise for longer periods of time. This results in burning more calories, increasing cardiac efficiency, and delaying anaerobic glycolysis and the resulting buildup of lactic acid during exercise. Reports of Yerba Tea reducing blood pressure are not uncommon. A consistent observation in most South American literature on Yerba Maté is that it increases the immune response of the body, stimulating natural resistance to disease. This results in a nourishing and strengthening effect on the ill person, both during the course of the illness and during convalescence, sometimes dramatically accelerating recovery times. Exact mechanisms of Yerba Maté's action have not been worked out, but they involve both a direct action against infectious organisms, and an effect on overall resistance to disease. The nutritional content of the plant probably plays a major role here, but it is also probable that other constituents contribute to the action by stimulating the activity of white blood cells. The interaction of the many nutrients in Yerba Maté have never been systematically studied. But the stories surrounding the nutritional application of Maté Tea are nothing short of amazing. Yerba Maté is often used as a staple food, sometimes substituting for such important foods as bread and vegetables. It easily eliminates the sensation of hunger and can impart as much invigoration as a full meal, according to the well-known Chilean herbalists J. Zin and R. Weiss. Peace Corps workers have reported cases in which large groups of natives remain in good health for extended periods of drought and famine, even though they eat only one small meal per day. How so? By drinking copious amounts of Yerba Maté Tea. Some natives spend their entire lives on such a diet and live to very advanced ages, sometimes in excess of 100 years. South American governments have adopted the practice of encouraging mothers, especially in the poorer regions, to include Yerba Maté in the diet of their school-age children.