Guarana, made from the seeds of a plant grown in the Amazon region, finds its way into a number of energy drinks and weight loss supplements. Guarana’s effects come mostly from its high caffeine content; guarana naturally contains 2.5 to 7 percent caffeine, compared to 1 to 2 percent in coffee, the University of Salisbury Nursing Department reports. Guarana supplements, like all over-the-counter supplements, are not regulated by the United States Food and Drug Administration. Guarana also has a number of unpleasant and possibly dangerous side effects, so do not take this supplement without your doctor’s approval.
Typical over-the-counter supplements contain 800 milligrams of guarana, which is taken before each meal to decrease appetite. Since stimulants like guarana and caffeine can depress appetite, taking guarana before each meal may decrease your daily calorie intake. Guarana, like caffeine, also acts as a diuretic, so you urinate more, which can result in weight loss. Loss of water weight, while inspiring on the scale, doesn’t reduce fat stores. Stimulants like guarana also increase heart rate and may speed up your metabolism, resulting in more calories burned. The daily dose should not exceed 3 grams, the University of Salisbury Nursing Department states.
A study of weight and fat loss in 67 persons taking guarana and ma huang was conducted by the Obesity Research Center at St. Luke's-Roosevelt Hospital Center and Department of Medicine. Lead author C.N. Boozer reported the results in the March 2001 issue of “International Journal of Obesity and Related Metabolic Disorders.” Forty-eight people completed the study, which ran for eight weeks, during which eight out of 35 treated with the active drug dropped out due to side effects. The active group lost more weight and body fat than the placebo group.
Guarana, like other central nervous system stimulants, can cause unpleasant side effects, which may vary from person to person. For some people, 800 milligrams before each meal may be an excessive dose, since no safe dose has been established. Typical side effects include jitteriness, trouble sleeping, anxiety, restlessness, nervousness, irritability, shakiness, dry mouth, headache, heartburn, stomach upset, including nausea or vomiting, and constipation or diarrhea. Some people also experience a ringing in the ears known as tinnitus.
Guarana can cause irregular heartbeat, including an increased heart rate or skipped beats. Guarana can also raise your blood pressure. If you take drugs called MAO inhibitors, guarana can cause hypertensive crisis. MAO inhibitors, which stands for monoamine oxidase inhibitors, are a class of drugs used to treat depression. Guarana also raises blood glucose levels, so diabetics should monitor their blood sugars carefully. Pregnant women or people with heart conditions should not take this drug.