Obesity has become a global health concern and can lead to metabolic syndrome, a group of conditions that includes high blood pressure, LDL cholesterol and triglycerides. The rise in obesity has led to an interest in potential medications and functional foods for treatment and prevention. Coffee and its components, including caffeine, currently are being studied for their role in weight management.
Caffeine Metabolism
Caffeine is absorbed through the gut and metabolized in the liver. Although caffeine can be detected in the blood as soon as 15 to 45 minutes after ingestion, its peak level is seen at about an hour after consumption. Caffeine affects both the central and peripheral nervous systems, decreases reliance on glucose in the bloodstream and increases fat utilization. Coffee is the most widely consumed form of caffeine, but its effect on human metabolism has not been decisively determined because many studies use animal models and caffeine in the form of capsules rather than in regular coffee.
Coffee, Caffeine, and Energy Expenditure
A 2007 study published in "Obesity" found that a beverage containing caffeine, green tea catechins and calcium increased metabolism by 4.6 percent up to 24 hours after ingestion. However, it was not clear whether the increase in metabolism stemmed directly from caffeine or the other ingredients in the beverage. According to a 2011 study published in the "American Journal of Physiology, Endocrinology and Metabolism," coffee polyphenols, which are compounds, might increase metabolism and reduce body fat accumulation. However, this study was performed on mice and cannot be generalized to humans.
Caffeine and Sports Performance
When caffeine is consumed in low to moderate doses -- about two to three cups of regular coffee, for example -- it can improve sports performance by increasing endurance, according to a 2010 position stand from the "International Journal of Sports Nutrition." Additionally, according to a 2008 study published in the "Journal of Applied Physiology," endurance athletes who consume caffeine in combination with a carbohydrate source can experience better post-workout recovery, possibly by increasing the synthesis of glycogen, the storage form of glucose. However, in this study caffeine was added to a sports drink and was not consumed in the form of regular coffee.
Considerations
It still is too early to say whether drinking coffee increases metabolism in humans. However, you can feel good about drinking your morning cup of Joe because of its proven ability to increase alertness, the body's ability to burn fat during exercise and performance in endurance athletes.
References
- "Journal of the International Society of Sports Nutrition"; International Society of Sports Nutrition Position Stand: Caffeine and Performance; Erica Goldstein et al.; January 2010
- "The Journal of Applied Physiology"; High Rates of Muscle Glycogen Resynthesis After Exhaustive Exercise when Carbohydrate is Co-Ingested with Caffeine; David Pedersen et al.; April 2008
- "Obesity"; Effect of a Thermogenic Beverage on 24-Hour Energy Metabolism in Humans; Servane Rudelle et al.; 2007
- "The American Journal of Physiology, Endocrinology and Metabolism"; Coffee Polyphenols Suppress Diet-Induced Body Fat Accumulation By Downregulating SREBP-1c and Related Molecules in C57BL/6J Mice; Takatoshi Murase et al.; January 2011
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