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Caffeine and Weight Loss

Jane Slatton

October 5, 2009


What is Caffeine?

        The Oxford English Dictionary defines caffeine as a “vegetable alkaloid crystallizing in white silky needles, found in the leaves and seeds of the coffee and tea plants, the leaves of guarana, maté, etc.”   It is commonly found in coffee, tea, sodas, or other energizing products.  Caffeine is also a stimulant, acting on the body’s Central Nervous System, which is why large amounts of caffeine can make a person jittery or over-stimulated. 

        Because of its stimulant properties, caffeine has been hypothesized to help cause, increase, or maintain weight loss.  


Caffeine and Weight Loss on the Web

        There are many claims on the Internet that caffeine can enable weight loss.  Some good examples of these claims are:


Hydroxycut Advanced


Hydroxycut Advanced’s main ingredient is caffeine anhydrous (waterless caffeine).  It asserts that it will burn calories, boost metabolism, and increase energy.  Though it now calls itself a dietary supplement, hydroxycut mainly advertises its ability to burn calories and boost metabolism, which would cause weight loss, based on the main ingredient: caffeine. 


Holy Mountain Teas


This is a tea website that states that caffeine has positive effects on the mind and body.  It states: “the physical effects include stimulation of digestive juice, the kidneys, and the metabolism in ways that possibly help eliminate toxins. An increasing of mental alertness, shortening of reaction time, and improving efficiency of muscle action is brought about by caffeine's stimulation of the heart and respiratory system, bringing more oxygen to the brain.”  This website makes many claims about the benefits of caffeine, without actually citing any scientific sources.  The caffeine from Holy Mountain’s teas will apparently stimulate digestive juices, affect kidneys, and change metabolism to get rid of toxins.  These effects paired with improved muscle efficiency promise an effect that will change your body for the better, and possibly cause weight loss.




This site is promoting the WARP 9, a weight loss pill, which uses caffeine to stimulate your metabolism, help you burn fat, and stop the growth in tissues that store fat.  It states that caffeine helps you maintain Basal Metabolic Rate, even when going on extreme diets that cause your metabolism to slow down.  The site vaguely mentions many studies about the effect of caffeine on exercise and weight loss, while only citing four studies, some of which I could not find on the internet.  The site states, “WARP 9 contains just the right amount of caffeine (250 mg about the same amount as 14-16 oz of coffee) and provides synergistic nutrients to help increase metabolism, enhance athletic performance and induce weight loss through thermogenesis.”


What THEY want you to believe

        Products like the three examples above, use caffeine as the main ingredient to cause an improvement in body functioning, usually resulting in weight loss.  For this reason, they want you to believe that caffeine will boost your metabolism, increase your energy, help you work out better and longer, burn your fat stores, stimulate your digestive juices, and help you lose tons of weight.  It is in the best interest of each of these companies to promote their product at the easy, safe, effective way to lose weight or improve your body.  These products are moneymakers for companies, and the more people convinced that the product is the best solution, the more money each company will make.  


Will it work?

        Much research has been conducted about the true effects of caffeine on our bodies.  A study by Kovacs et al (2004) tested the ability of green tea to maintain weight loss in a group of participants who had recently loss 7.5% of their body weight.  To ensure external validity, the study did not alter the participants’ current food or drink intake, but rather added either green tea or a placebo into their diets.  Unfortunately, the study found that the group given green tea did not experience better weight loss maintenance than the placebo group.  It also found that those participants who already had a habitually higher caffeine intake experienced fewer effects, indicating that one can become habituated to the possible initial positive effects of caffeine. 


        Some products assert that caffeine improves one’s ability to perform athletically, indirectly enabling weight loss.  The evidence on caffeine’s effectiveness in athletic performance is mixed.  Jackman et al (1996) concluded that caffeine ingestion improved endurance for exercise even at 4-6 minute intervals.  They tested two groups of participants, one given a placebo capsule and one given a capsule with caffeine (6mg/kg body weight).  The group with the caffeinated capsules outperformed the group with placebo capsules.


However, another study by Greer et al (1998) found that caffeine did not affect participants performing a series of Wingate sprints.  The study gave two groups either a placebo or a capsule of caffeine (6mk/kg body weight).  After four short-term intense sprints, the study found that anaerobic metabolism was not increased in participants given caffeine.  The study also found that caffeine did not improve performance on the short-term intense exercise.

        The varied results from research lead to inconclusive findings.  Caffeine may enable people to perform at a higher level for less intense exercise and not affect intense exercise, or caffeine could influence each person differently.  From the body of research available, it seems unlikely that caffeine will produce a certain improvement in athletic performance.


        Caffeine might actually cause a person negative effects.  A study done by Lovalloa et al (2006) found that caffeine consumption could raise cortisol levels in the body.  The study examined the physiological effects of caffeine when given to participants throughout the day.  Data were taken on a normal day with no extra stress and on days in which the participants experienced either a mental stressor or did physical exercise.  Cortisol levels after caffeine were found to be higher in women after a mental stress and higher in men after physical exercise, but in a significant amount of cases over all situations, caffeine produced more cortisol.  Because cortisol can slow down digestion and therefore lead to weight gain (Andrew et al, 1998), this finding indicates that a dosage of caffeine might inhibit weight loss and even promote weight gain.


Is it all bad?

        Even though the research about caffeine’s effects on weight loss is not positive, some studies have reported positive effects of caffeine on overall health.  A review of literature by van Dam and Hu (2005) suggests that, “participants who drank 4 to 6 cups and more than 6 to 7 cups of coffee per day had a 28% and 35% lower risk of type 2 diabetes compared with those who drank less than 2 cups per day.”  This meta-analysis suggests that coffee drinking may actually help a person’s overall health by preventing Type II diabetes, a disease associated with obesity.  Some of the mechanisms attributed to coffee’s ability to prevent diabetes including the high levels of magnesium, which contribute to insulin sensitivity.  Coffee also contains chlorogenic acid, which decreases glucose concentration and can increase insulin sensitivity.




        After a thorough search of the available research on caffeine and weight loss, one can conclude that caffeine alone cannot cause, prevent, or maintain weight loss.  The literature on exercise performance enhancement is mixed, and therefore weight loss caused indirectly by caffeine is not certain.  In studies that showed reduced weight in participants, counseling was provided about eating a balanced diet and exercising regularly.  The available literature suggesting that coffee can prevent Type II diabetes suggests that while caffeine may not be positive for weight loss, as suggested by products like Hydroxycut, it may help with other health aspects. 

        Therefore, products that assert that they will boost metabolism and burn calories cannot be resoundingly trusted.  Weight loss is only guaranteed through a change in diet and an increase in exercise.  The addition of caffeine is not necessarily a negative addition, but caffeine alone cannot guarantee weight loss.




Andrew, R., Phillips, D. I. W., & Walker, B. (1998). Obesity and Gender Influence Cortisol Secretion and Metabolism in Man, The Journal of Clinical Endocrinology & Metabolism, 83, 1806


Caffeine. (1989). In Oxford English Dictionary Online. Retrieved from


Greer, F., McLean, C., & Graham, T. E. (1998). Caffeine, performance, and metabolism during repeated Wingate exercise tests. Journal of Applied Physiology, 85 (4),1502-1508.


Jackman, M., P. Wendling, D. Friars, & T. E. Graham. (1996). Metabolic, catecholamine, and endurance responses to caffeine during intense exercise. Journal of Applied Physiology, 81: 1658-1663, 1996


Kovacs, E. M. R., Lejeune, M. P. G. M., Nijs, I., & Westerterp-Plantegna, M. S. (2004). Effects of green tea on weight maintenance after body-weight loss. The Netherlands British Journal of Nutrition, 91, 431-437.


Lovalloa, W. R., Faragb, N. H., Vincentc, A. S., Thomas T. L., & Wilson M. F. (2006). Cortisol responses to mental stress, exercise, and meals following caffeine intake in men and women. Pharmacology Biochemistry and Behavior, 83 (3), 441-447.


Van Dam, R. M. & Hu, F. B., (2005). Coffee Consumption and Risk of Type 2 Diabetes:

A Systematic Review. Journal of the American Medical Association, 294: 97-104.