Green tea (Camellia sinensis)

  • What it is: Researchers are finding that the antioxidant compounds (polyphenols) that make green tea a potent protector against cancer and heart disease also aid weight loss efforts. Although black, oolong, and green teas all come from the same evergreen shrub, green tea contains far more polyphenols because the leaves are not fermented before being steamed or dried.
  • How it works: A cornerstone of successful weight loss is to increase energy expenditure. Green tea contains a unique polyphenol called epigallocatechin gallate (EGCG) that increases calories burned by stimulating production of the hormone noradrenaline.
    In a recent study reported in the American Journal of Clinical Nutrition, Japanese researchers found that overweight men given oolong tea fortified with green tea extract containing 690 mg of catechins lost approximately two times more weight than those drinking plain oolong tea with only 22 mg of catechins (2005, vol. 81, no. 1). Unlike stimulant diet drugs, green tea doesn't increase heart rate or trigger dangerous heart rhythm disturbances. However, green tea does contain caffeine (about half the amount of coffee) and can cause nervousness, insomnia, irritability, and headaches in people who are sensitive to caffeine.
  • How to take it: Green tea is widely available as a tea, liquid extract, and in capsules. An average dose is four cups of tea daily. For standardized extracts, follow the manufacturer's dosage recommendations.

Garcinia cambogia (Garcinia cambogia)

  • What it is: Also known as Malabar tamarind, Garcinia cambogia is a small purple fruit native to Southeast Asia with a sweet-sour flavor. Concentrated extracts of the fruit are available as hydroxycitric acid (HCA). Research studies show that HCA inhibits enzymes that convert carbohydrates into fat and puts the brakes on appetite.
  • How it works: In a 2004 joint study by Georgetown University Medical Center in Washington, D.C., and Andhra University in India, researchers found that a highly soluble, standardized form of HCA reduced nearly three times as much body weight as diet and exercise alone. Participants taking HCA also showed increased excretion of fat metabolites (an indication of fat "burning") and higher serotonin levels, which help to regulate appetite (Nutrition Research, 2004, vol. 24, no. 1).
    Clinical studies haven't unequivocally proven HCA's effectiveness, but proponents of the supplement note that taking too little HCA or eating a high-fiber diet (which interferes with HCA's absorption) can impede results. Because it has been used for a long time as a traditional food and flavoring in Southeast Asia, Garcinia cambogia is considered safe.
  • How to take it: A typical dose of HCA is 250–1,500 mg three times daily. Best results are obtained when taken 30 to 60 minutes before meals. Products are often labeled Garcinia cambogia and are standardized for HCA content.

Glucomannan (Amorphophallus konjac)

  • What it is: A soluble fiber, glucomannan is derived from the root of the konjac plant (also called elephant yam), which is native to Asia. Researchers have found that glucomannan promotes weight loss and improves intestinal health and blood sugar control.
  • How it works: Because glucomannan can absorb up to 200 times its weight in water, it provides feelings of fullness that make sticking to a diet easier. Studies on glucomannan show that the fiber supplement reduces fat absorption, promotes blood sugar control, lowers cholesterol and triglyceride levels, and encourages the growth of beneficial intestinal bacteria.
    In a 1992 Italian study, researchers compared two groups of severely obese patients, both following a low-calorie diet, but one also taking 4 grams daily of glucomannan. They found that the group taking the glucomannan lost more weight and had improved cholesterol and triglyceride levels and better blood sugar control than those on only the diet. The glucomannan group also had an easier time adhering to the diet (Minerva Medica, 1992, vol. 83, no. 3).
  • How to take it: A typical dose of glucomannan is 1 gram consumed with 8 ounces of water approximately one hour before a meal, three times a day.

Herbalist and author Laurel Vukovic lives in Ashland, Oregon, and has published nine books, including Herbal Healing Secrets for Women (Prentice Hall, 2000).