Caffeine and Your Metabolism

Does caffeine help you lose weight?

A commonly held belief related to caffeine and your metabolism is that drinking coffee will aid with weight loss. Caffeine does in fact increase the resting metabolic rate and helps your body burn fat through thermogenesis. However, many people don’t realize that over time this effect will wear off for the habitual coffee drinker as caffeine tolerance increases. 1

To continue to benefit from a caffeine-induced boost to the metabolism, a coffee drinker would have to consume more and more caffeine over time, putting their body in a constant state of stress and suffering the many negative side effects of caffeine. Additionally, we are not all created equal when it comes to our body’s ability to break down caffeine.

Genetic differences and caffeine metabolism

Newly identified genetic differences reveal that caffeine metabolism is mediated by genetics related to variations of a specific gene. Approximately 50% of the population possesses the slow metabolizing allele, or variation of the gene, meaning these people process caffeine in the liver at a much slower rate than those who are identified as fast metabolizers.2

In the slow metabolizers, caffeine has the potential to build up in the bloodstream before the liver is able to detoxify it (particularly when people are consuming multiple cups of coffee or other caffeinated drinks). Increased risk of hypertension is correlated with carriers of the slow variation of the gene. These people also have higher levels of epinephrine (adrenaline) in their urine. Caffeine is known to stimulate the release of hormones related to the sympathetic nervous system response, including epinephrine.3

Sensitivity to caffeine does not necessarily correlate with whether or not someone is a slow or a fast metabolizer of the chemical. Fast metabolizers can still be sensitive to and get the jitters from drinking coffee! Differences in caffeine metabolism can also provide an explanation as to why the research results related to the health effects of caffeine can be so divergent, as different people are dramatically differentially sensitive.

Prescription drugs compete with caffeine for processing time in the liver

Caffeine is metabolized by the cytochrome P450 pathways in liver. Most pharmaceutical drugs also utilize this same metabolic pathway, including oral contraceptives and antidepressants.4 When caffeine is consumed with other substances, the rate of clearance of both the caffeine and the drugs from the body is significantly reduced.5 Caffeine, therefore, remains in the body for much longer periods of time, increasing the effect of the morning cup of coffee.

Unless your doctor recommends that you drink coffee, we suggest those people taking prescription medications stay away from coffee to avoid unpleasant side effects of too much caffeine.



Ammon, H 1991; Westerterp-Plantenga, et al 2005
Cornelis, et al, JAMA, 2006
Cornelis, et al 2006; Palatini, et al 2009
Carillo and Benitez 2000
Labbe, et al 1999; Abernethy, et al 1985; Patwardhan, et al 1980; Rietveld, et al 1984


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Cornelis, M. C., El-Sohemy, A., Kabagambe, E.K., and Campos, H., 2006. Coffee, CYP1A2 Geontype, and Risk of Myocardial Infarction. Journal of the American Medical Association. 295(10):1135-1141.

Ferrini, R.L. and Barrett-Connor, E.. 1996. Caffeine intake and endogenous sex steroid levels in postmenopausal women. The Rancho Bernardo Study. American Journal of Epidemiology. 144(7):642-4.

JAMA, et al.March 8, 2006—Vol 295, No. 10

Labbe, L., Abolfathi, Z., Robitaille, N.M., St-Maurice, F., Gilbert, M. and Turgeon, J. 1999. Stereoselective disposition of the antiarrhythmic agent mexiletine during the concomitant administration of caffeine. Therapeutic Drug Monitor. 21(2):191-9.

Mathias, S., Garland, C., Barrett-Connor, E. and Wingard, D.L. 1985. Coffee, plasma cholesterol, and lipoproteins. A population study in an adult community. American Journal of Epidemiology. 121(6):896-905.

Patantini, P., Ceolotto, G., Ragazzo, R., Dorigatti, Fr., Saladini, F., Papparella, I., Mos, L., Zanata, G., Santonastaso, M. 2009. CYP1A2 genotype modifies the association between coffee intake and the risk of hypertension. Journal of Hypertension. 27(8): 1594-601.

Patwardhan, R.V., Desmond, P.V., Johnson, R.F. and Schenker, S. 1980. Impaired elimination of caffeine by oral contraceptive steroids The Journal of laboratory and clinical medicine. 95(4):603-8.

Rietveld, E.C., Broekman, M.M., Houben, J.J., Eskes, T.K. and van Rossum, J.M. 1984. Rapid onset of an increase in caffeine residence time in young women due to oral contraceptive steroids. European Journal of Clinical Pharmacology. 26(3):371-3.

Westerterp-Plantenga, et al. 2005. Body weight loss and weight maintenance in relation to habitual caffeine intake and green tea supplementation. Obesity Research and Clinical Practice. Jul 13(7):1195-204.