For decades, studies have shown that caffeine, a stimulant found in coffee, tea and many soft drinks, increases resting metabolic rate. Your resting metabolic rate, also known as your basal metabolic rate, or BMR, determines the number of calories you burn each day through daily functions.
Increased Metabolic Rate
A 1989 study published in the "American Journal of Clinical Nutrition" found that a single, 100-mg dose of caffeine increased the resting metabolic rate of lean and obese subjects by 3 to 4 percent over 150 minutes. The same dose of caffeine provided every two hours over a 12-hour period increased the energy expenditure of lean and obese subjects by 8 to 11 percent, resulting in an additional 150 calories burned in lean subjects and an additional 79 burned in obese subjects. In a 2003 study, researchers at the Agricultural Research Service's Diet and Human Performance Laboratory found that volunteers who drank caffeinated water or tea experienced a 3 percent increase in energy expenditure, burning an average of 67 calories more than subjects who drank only water.
Fat Oxidation
In addition to boosting your metabolism, caffeine may also cause you to burn more fat. A 1980 study published in the "American Journal of Clinical Nutrition" found that consumption of caffeinated coffee increased fat oxidation to a greater extent in normal weight individuals than in obese individuals. A 1995 study published in the "American Journal of Physiology" found that, while the effect of coffee on metabolic rate had ceased by the day after caffeine consumption, lipid oxidation remained higher in both lean and obese women. Lean women experienced a 29 percent increase in lipid oxidation, and obese women experienced a 10 percent increase. In 2003, researchers at the Agricultural Research Service's Diet and Human Performance Laboratory found that tea had a similar effect on fat oxidation. Caffeinated tea boosted fat oxidation 12 percent more than mere caffeinated water, leading researchers to hypothesize that the combination of caffeine and catechins active in tea may cause a higher increase in fat oxidation than caffeine alone.
Other Possible Health Benefits
Research has suggested that consumption of caffeinated coffee may help prevent Parkinson's disease, liver cancer, liver cirrhosis, cardiovascular disease and Type 2 diabetes, according to Dr. Rob van Dam of the Harvard School of Public Health. More studies need to be done in this area, however, suggests van Dam.
Warning
Pregnant women and individuals struggling to control blood pressure or blood sugar should choose decaffeinated coffee and tea and avoid caffeine. Caffeine can decrease insulin sensitivity and increase blood glucose levels in diabetics.
References
- "American Journal of Clinical Nutrition"; Caffeine and Coffee: Their Influence on Metabolic Rate and Substrate Utilization in Normal Weight and Obese Individuals; KJ Acheson, et al.; May 1980
- "American Journal of Clinical Nutrition"; Normal Caffeine Consumption: Influence on Thermogenesis and Daily Energy Expenditure in Lean and Postobese Human Volunteers
- USDA Agricultural Research Service; Brewing Up the Latest Tea Research; September 2003
- "American Journal of Physiology"; Effects of Caffeine on Energy Metabolism, Heart Rate, and Methylxanthine Metabolism in Lean and Obese Women; D. Bracco, et al.; October 1995
- Harvard School of Public Health; Ask the Expert: Coffee and Health; Dr. Rob van Dam; 2008
- MayoClinic.com: Metabolism and Weight Loss
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