The incidence of obesity has increased significantly in the past decade, along with obesity-related illnesses such as diabetes and heart disease. According to the U.S. Centers for Disease Control and Prevention, the incidence of diabetes alone may triple by 2050. Medical experts are exhorting overweight individuals to change their eating habits and increase their activity levels. Scientists are earnestly examining specific dietary behaviors such as green tea consumption that may contribute to weight loss.
The concept of “functional foods” has been discussed in the scientific literature for at least two decades. In 1994, the Institute of Medicine defined a functional food as “any food or food ingredient that may provide a health benefit beyond the traditional nutrients it contains.” Examples of such health benefits include antioxidant, anti-inflammatory or anti-tumor properties. Thus, fish oil, red wine and green tea can be considered functional foods owing to their content of omega-3 fatty acids, resveratrol and polyphenols, respectively. America’s obesity epidemic has made the search for functional foods that improve weight control particularly relevant.
One notion that has captured the minds of scientists -- and the hearts of people who are trying to lose weight -- is a property called “thermogenesis,” which refers to a food’s innate ability to increase your metabolic rate. Caffeine serves as a prototypical thermogenic agent, due to its ability to increase the activity of your sympathetic nervous system. However, a study published in the October 1995 issue of the “American Journal of Physiology” showed that the thermogenic effect of caffeine was actually blunted in obese women. In addition to its tendency to raise your heart rate and blood pressure, this could make caffeine a poor choice for weight loss.
A clinical trial published in the December 1999 issue of “The American Journal of Clinical Nutrition” suggested that green tea possesses thermogenic properties beyond those that can be explained by its caffeine content alone, and that this functional effect of green tea could be useful for the management of obesity. This study used a green tea extract containing 90 milligrams of a flavonoid called epigallocatechin gallate, which the subjects consumed three times over one 24-hour period. Energy metabolism and fat burning activity were stimulated in subjects consuming the green tea extract, but not in subjects consuming an equivalent amount of caffeine alone.
Consult with your doctor before using green tea for weight management. The recommendation that overweight individuals reduce their caloric intake and increase their levels of physical activity is based on a consensus that these are the only known methods to effectively achieve and maintain weight loss. The addition of functional foods or supplements that reputedly increase your metabolic rate may provide additional benefits, but such measures cannot be expected to confer significant weight loss on their own.
- U.S. Centers for Disease Control and Prevention: Number of Americans with Diabetes Expected to Double or Triple by 2050
- Institute of Food Technologists: Functional Foods - Their Role in Disease Prevention and Health Promotion; Claire M. Hasler, Ph.D.
- American Journal of Physiology: Effects of Caffeine on Energy Metabolism, Heart Rate, and Methylxanthine Metabolism in Lean and Obese Women
- The American Journal of Clinical Nutrition: Efficacy of a Green Tea Extract Rich in Catechin Polyphenols and Caffeine in Increasing 24-Hour Energy Expenditure and Fat Oxidation in Humans
- American Family Physician: Green Tea - Potential Health Benefits
- green tea image by Maria Brzostowska from Fotolia.com
This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.