Yerba mate is a South American plant whose leaves are dried and made into tea or put into capsules. The herb contains vitamins A, B-complex, and C, and the minerals calcium, magnesium, and iron.
Yerba mate is usually touted as a natural upper. And for good reason: It is a central nervous system stimulant. But the herb's invigorating or fatigue-reducing effect is due mostly to its 2 percent caffeine content.
Yerba mate is found in some natural weight-loss supplements because it is believed to help control appetite, although there is no concrete proof of this. What is known, however, is that the herb has a mild diuretic effect. As with any diuretic, supplementing with it might produce temporary water weight loss.
Potential side effects of yerba mate may include confusion, excessive urination, irritability, nausea, nervousness, and rapid heartbeat. Consumed in very large amounts, yerba mate tea (also known as Paraguay tea) may be cancer-causing. However, medical experts say the herb is relatively safe when taken in small quantities for short periods of time.
Yohimbe is an herb derived from the bark of an evergreen grown in West Africa. It is best known for its aphrodisiac properties because it stimulates erection. An extract of the herb, yohimbine, is available as a prescription drug for treating erection problems.
Yohimbine is ail FDA-approved treatment for erection impairment, and it produces good results. What is less certain about the herb or its extract is its effect on fat loss. Yohimbine stimulates the release of noradrenaline (norepinephrine), a hormone that raises body temperature and helps liberate fatty acids from cells to be burned as fuel. When patients on a 1,000-calorie-a-day diet supplemented with yohimbine hydrochloride (a prescription medicine), they lost an average of 7.8 pounds in 3 weeks, compared with a control group who lost an average of 4.8 pounds. Whether or not the whole herb yohimbe produces the same effect is unclear. Still, the herb is included in some natural weight-loss formulas.
Yohimbe is considered a dangerous herb, even by herbalists' standards. It can cause anxiety, elevated blood pressure, irregular heartbeat, headaches, painful erections, flushing, hallucinations, kidney failure, seizures, and death. The prescription form of the herb produces fewer side effects. This is one of those rare exceptions in which the raw herb is more toxic than its pharmaceutical cousin. It's best to avoid any natural weight-loss formula containing yohimbe. In fact, the American Botanical Council, which promotes herbal supplements, has recommended that consumers avoid it. Further, the FDA considers it to be potentially unsafe.
The yucca plant is a member of the lily family that has been used by Native Americans in the southwestern United States to treat colds, flu, indigestion, and constipation.
A 1992 article published in Health News & Reviews related the story of an anthropology professor who went on a diet of desert herbs, including yucca blossoms, and lost 30 pounds in 3 months. The truth be told, there is no scientific evidence supporting yucca as a weight-loss agent, although you may find it listed as an ingredient in some natural weight-loss products.
Yucca is probably safe in the trace amounts found in natural weight-loss supplements.