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Does Caffeine Slow Down the Metabolism?

Caffeine, a stimulant found in most coffee, tea and sodas, actually boosts the metabolism, studies show. Caffeine’s effect on the metabolism causes only a minimal increase in the number of calories burned, and probably does not contribute to weight loss. Still, research has shown that caffeine may benefit your health in several other ways.

A study published in the “American Journal of Clinical Nutrition” showed that 100 mg doses of caffeine caused a 3 to 4 percent increase in resting metabolic rate in both lean and obese subjects. This increased metabolism lasted for about 150 minutes after consumption of caffeine. When subjects consumed 100 mg of caffeine every two hours for a 12-hour period, they experienced 8 to 11 percent higher energy expenditure. Obese subjects burned an average of 79 additional calories and lean subjects burned an average of 150 additional calories. A 2003 study performed by scientists at the Agricultural Research Service’s Diet and Human Performance Laboratory showed that consumption of caffeinated water or tea caused a 3 percent increase in energy expenditure.

Your BMR, or basal metabolic rate, determines the number of calories you burn at rest and through daily functions. The speed of your metabolism depends on a variety of factors, including your age, gender and the percentage of fat and muscle in your body. Basal metabolic rate accounts for up to 75 percent of the calories you burn each day. Thermogenesis, or food processing, accounts for 10 percent of the calories you burn each day. Caffeine increases the number of calories you burn through thermogenesis, according to a study in the “American Journal of Clinical Nutrition.”

Caffeine not only boosts your metabolism, it also increases the amount of fat you burn, studies show. A study in the “American Journal of Physiology” found that consumption of caffeinated coffee increased lipid oxidation in lean and obese women, and that this increase persisted the day after caffeine consumption. Caffeine caused a 29 percent increase in lipid oxidation in lean women and a 10 percent increase in obese women. In a 2003 study performed by the Agricultural Research Service’s Diet and Human Performance Laboratory, participants who drank caffeinated tea experienced a 12 percent greater increase in fat oxidation than those who drank caffeinated water. When combined with catechins found in tea, caffeine may cause an even greater increase in fat oxidation, the researchers hypothesized.

Daily consumption of caffeinated coffee may have some health benefits. These benefits include a reduction in your risk of several diseases, including Type 2 diabetes, cardiovascular disease, Parkinson’s disease, liver cancer and liver cirrhosis, according to Dr. Rob van Dam of the Harvard School of Public Health. More studies need to be conducted to confirm these health benefits.

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This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.