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Caffeine’s Effect on Body Fat


Bethany Gonzales


September 24, 2007


            The American dream is to do it all and have it all, from small beginnings to unimaginable success. With this dream has come a plethora of side effects. As America’s obesity rate increases so do the weight loss “miracles.” Over the last decades we have been in pursuit of a magic pill or drink that will enable us to continue to eat high calorie, low nutrition foods without having to do dreaded exercise that will cut into our leisure time. Besides our weight problems we are finding that we have less energy to put into our hectic, over planned schedules. Coffee and/or certain teas have been praised for meeting both these needs; giving us the burst of energy we need to do it all and helping us lose weight so we can have it all.

With many people already drinking coffee or tea, knowing how their consumption may effect weight is valuable in the way we drink coffee or tea. In the second chapter of Health Psychology: A Biopsychosocial Approach, Straub brings to light the uncertainty surrounding caffeine. Caffeine has been characterized as producing heart problems and putting people with high blood pressure or other existing heart diseases at a greater risk( Dullo, 1999.) However, in recent years it has been hailed as a protective agent against Parkinson’s disease, and in teenagers a protective agent against hypertension, and cardiovascular disease. (Straub, 28)

For example if only the caffeine effects only a small increase in metabolism than adding creamer, sugar and a scone will negate that effect and is likely to cause an increase in our body mass index (BMI.) Furthermore, if caffeine is added by the chemical compounds found in tea than switching from a cup of coffee with sugar to a cup of black or green tea may improve our weight status significantly. Upon further inquiry, how does tea or coffee aid in maintaining weight loss. What about the people that do not need to lose weight? If a person does not need to lose weight, is drinking coffee or tea detrimental to their health? These questions and more are important when assessing the cost and benefits of caffeine to our health. Assessing the risks of any weight loss regimen is important before beginning it. It is good to consider not only the short term advantages and risks, but also the long term costs and benefits.


Evidence for Caffeine’s Benefit

The Joy of Caffeine Consumption


·         Short Term Effects – Maintaining Weight Loss

Westerterp-Plantenga et al investigated the effect of caffeine on people who had recently lost weight. Caffeine appears to aid people in keeping the weight off long term or at least for the 3 month follow up that they conducted. This randomized double blind placebo-drug study, began by having all the participants lose 7% +/- 2.1% of their body weight then beginning a 150mg dose of caffeine per day or a placebo. Westerterp-Plantenga et al propose that caffeine increases energy expenditure resulting in thermogenesis and that caffeine enters into the “fight or flight” system activating the production of glycogen and using up the cyclic AMP to oxidize fat cells, which makes them more available for consumption during thermogenesis.

This is supported by the previously mentioned fact that caffeine is an antagonist drug that inhibits adenosine, which is implicated in the “fight of flight” response with its association to epinephrine, norepinephrine, and noradrenaline release (Bell, 2002; Dulloo, 1999.) One readily available consequence of caffeine is that there are other drugs that are considered antagonist and caffeine is like them in that you can develop a dependency and you will go through withdrawals if you discontinue consumption abruptly. Withdrawals include, but are not limited to, headaches, nauseous, and irritability.

However the argument concerning the level of a hormone, leptin, that is released by adipose (fat) tissue has been seen to change with caffeine intake as a result of the regulation of adrenoceptors. This is once again part of the same “fight or flight” system, the sympathetic nervous system. Leptin levels were measured and the theory raised in this study about caffeine’s efficacy seemed to be centered around the regulation of leptin in the body. They offered the findings that long term use of caffeine resulted in lower leptin levels, which may be misleading. (Westerterp-Plantenga, 2005)

Leptin is a hormone that has been implicated in hunger regulation (Straub, 199)  Leptin levels cannot be understood with a simple linear relationship between hunger and obesity because, just like many other hormones in the body, it feeds back into the system that produces it to create more (or less) of the hormone. Therefore, you see both heightened levels of Leptin when you lose fat at the beginning of a diet and when you are gaining fat. In the first case of higher Leptin levels causes hunger to increase and slow down metabolism in contrast to these findings we see that in the second case the higher levels of Leptin occur as fat increases to actually suppresses hunger. One explanation for the differences in Leptin's function is that Leptin is a hormone of  evolutionary survival. Thus, if you are in the middle of a famine (analogous to a diet) your chances of survival increase if you are eating more (increase of hunger) and you store fat (metabolism slows) until more food is available. This works for the latter as well, if you have enough fat cells stored the Leptin feeds back into the system to stop the hunger signal because too many fat cells can raise the risk of heart disease, blood pressure, and diabetes as well as making it difficult to run from a predator if we think in a strictly evolutionary mindset.

This study also did a comparison of low caffeine or nonusers to high caffeine or users in both caffeine and placebo groups. The users may not have a response to the caffeine with regard to increased weight loss because they have lost the “sensitivity” to caffeine as a drug. Meaning their body is use to caffeine in the system and its effects are dampened. However, it should be noted that high caffeine users in the experimental (150 mg of caffeine per day) group still kept more weight off than the low caffeine users in the placebo group. (Westerterp-Plantenga, 2005)

The short falls of this study was the amount of caffeine administered. Other studies have shown that people that are classified as “users” or people that intake caffeine on a regular basis have a different response to caffeine in their system (Bell, 2002.) This study saw the effects of that interaction through the higher weight gain after weight loss of the caffeine users on a regimen of only 150mg. Another problem addressed in many other studies was the use of mg per kg of body weight. This would allow a more analogous concentration for the participants in either group. As it stands in this study the quantity of caffeine administered may be a confound as the concentration is likely to be different in users and non-users when both groups are given the same amount and therefore causes an effect that was unexpected and uncontrolled. Another problem to consider is that this group of participants were on a weight loss program. While the caffeine group outperformed the placebo group it should be warned that results of caffeine’s effect may only be in addition to eating right and exercising and it is not clear that caffeine acts alone. This means that if you eat right and exercise caffeine can add an effect or work synergistically, but if you only begin a caffeine regimen without any change to diet or exercise you may see no benefit.

·         Short Term Effects – Reducing Weight Gain

Shimoda et al findings support the idea that caffeine can decrease the amount of fat a body absorbs when fat is being laid down, but the other ingredients in coffee beans, for example chlorogenic acid, aid in the metabolism of fat in other organs in the body like the liver. This study used 20 mg/kg and 40 mg/kg of caffeine to body weight for the experimental group for a total of 14 days. They had two control groups, one was a “positive control” group because they were given an anti-obesity drug (Orlistat) for comparison and the other group was a given neither treatment. The Orlistat group did not show any suppression of body weight but did show a small suppression of fat accumulation. Caffeine on the other hand showed improvements in body weight compared to the no treatment group and suppression of both epididymal and perirenal fat storage (Shimoda, 2006.)

It would be easy to criticize the findings from an animal study (using male mice) as not applicable to humans and our caffeine intake. However, coffee’s components (caffeine and chlorogenic acid) did cause decreased weight gain in the male mice. Furthermore, there are certain advantages that human studies do not have. For example all the mice were fed the same diet and could be monitored closely, while humans are assuredly on different diets and activity schedules and often falsify their reports of food consumption or actual body weight, when it is allowed to be self report.

In another rat study, caffeine was among several chemicals that were administered while observing weight gain due to fat storage. Xanthine, trimethylxanthine (caffeine), 1,3 dimethylxanthine (theophylline), and 3,7 dimethylxanthine (theobromine) were given to rats that had lard added to their diet. Inoue et al. found that the rats in the theobromine group had a higher body weight than the rats in the caffeine and theophylline groups. All of the experimental (methylxanthine derivatives) groups showed lower body fat percentages than the control group. (Inoue, 2006)


Caffeine Molecule (trimethylxanthine) made using ACD ChemSketch


            An interesting finding in this study was the lower levels of cholesterol and triglycerides in the caffeine group compared to the other experimental groups and the control. Many strokes and heart attacks can be prevented by lowering these two levels and Inoue and colleagues believe that their data shows caffeine is able to help lower them. This would make caffeine’s benefit from mere fat reducer to a protective factor regarding heart disease. Of course reducing your total body fat percentage is also a protective factor concerning heart disease. However, systolic blood pressure raises in a positive linear pattern with the increase of the amount of caffeine administered (Roberts, 2005.)

It is clear that more research in the future should focus on the causal relationship that caffeine has on heart disease. Some research has explored the effect of coffee on “acute coronary syndromes” (Panagiotakos, 2003), but this was a retrospective case-matched study. It suffered from relying on the ability of their participants to remember accurately the amount of coffee they drank per day on average, as well as the exclusion of other caffeine containing beverages and foods (coca-cola and chocolate) from their calculations. Shortcomings aside, Panagiotakos and colleagues have supported the hypothesis that a moderate amount of caffeine in your diet will protect against heart disease when compared to no caffeine, but caffeine increases your risk for heart diseases when you become classified as a “heavy drinker.”

Two sad “Heavy Coffee Drinkers”


·         Long Term Effects – Reducing Weight Gain

While the previous studies have shown compelling evidence for caffeine’s ability to make losing weight easier through chemical and neurological processes none of that data proves that the effect will last more than a year. Most people struggling to lose weight are not looking for several months of miniscule weight loss. Instead, they are looking for something that will continue to work and be effective over the years. 

Over a 12 year period, researchers found a small difference between groups of people that increased the amount of caffeine in their daily diet when compared to those that decreased their amount of caffeine. The differences were around a total loss of 0.40 kg of weight, while the difference in caffeine intake between groups ranged from an increase of 211 mg/day to reducing caffeine intake by 294 mg/day. (Lopez-Garcia, 2006)

            The long term effects of caffeine were monitored in 58,157 participants over the course of twelve years from 1986 to 1999. There is a tremendous amount of strength associated with the sample size and duration of this study. However, it is merely a correlational study not an experimental study in the sense that no variable was manipulated by the experimenter. Therefore a causal relationship should not be established due to the many uncontrolled and possibly confounding variables. For instance people that use caffeine more frequently and/or at greater quantities may have busier lifestyles or simply substitute high calorie meals with low calorie drinks (coffee or tea) that would be implicit in their weight loss or lower BMI than none caffeine users. The researchers could not control the diet that the participants were on or the other substances that they were using that could interact with caffeine, such as smokers and caffeine’s combined “synergistic” effect with nicotine to reduce fat storage (Lopez-Garcia, 2006.) Short falls aside, this study is still very valuable in assessing the possible influences that caffeine has on weight gain due to increased fat storage.

·         Other Interesting Interactions

Caffeine’s effect on fat storage in the short term and long term has been explored, but caffeine is a drug that effects more systems than the few we have mentioned so far. For instance, Santalla et al used “endurance trained university students” to show that caffeine can cause muscle fatigue when expending a large amount of energy by reducing the supply of oxygen to the tissue. They administered caffeine, a dose of 5 mg per kg of body mass, prior to exercise and observed changes in the volume of oxygen that you consume during exercise. A difference around 80 milliliters of oxygen per minute of exercise is decreased by consuming this relatively small does of caffeine prior to the activity. (Santalla, 2001.)


Conclusion & Cautions

·         Unanswered Questions

This raises the question, “How much is necessary to receive the benefits and at what point do you start doing more damage than good?” With some studies finding a difference between people that have caffeine as a regular part of their diet and those who abstain from caffeine containing items, even if we found an optimal mg of caffeine per kg of body weight we would need to then determine the individual’s sensitivity to caffeine and the concentration in blood that was optimal to gain as a fat reducer and not push the limits of becoming a risk for heart disease (Bell, 2002.) It would be even better if we found a point at which the two intersected, thus granting the benefits of weight loss and lowering the risk of heart diseases.


Exercise & Healthy Diet

Caffeine may significantly aid in weight loss through the reduction of body fat, but one must carefully weigh the risks. Take cigarettes as an example, the nicotine in cigarettes also aids in weight loss, but smoking is known to cause serious damages to your health, high blood pressure or lung cancer are seemingly not worth the little help it gives in weight loss. In light of better options, mainly exercising and eating right, the choice would seem clear. In the mean time it appears as though drinking moderate amounts of caffeinated beverages, such as coffee or tea, can aid in weight loss and maintenance and future research may confirm it as a protective factor for heart disease. It is should be noted that lower BMI is associated with better health outcomes. Being overweight or obese is associated with developing type II diabetes, heart disease, and high blood pressure as well as changing the quality of your life. From this body of research, if you want to lose significant amounts of body fat the best choice is to exercise and maintain a diet that is high in nutrients and low in fat. Adding a moderate amount of caffeine to assist your pursuit of a healthier lifestyle appears to help you reach your short term and long term goals.





Bell, D.B., & McLellan, T.M. (2002). Exercise endurance 1,3, and 6 hours after caffeine ingestion in caffeine users and nonusers. Journal of Applied Physiology, 93, 1227-1234.


Dulloo, A.G., Duret, C., Rohrer, D., Girardier, L., Mensi, N., Fathi, M., Chantre, P., & Vandermander, J.(1999). The American Journal of Clinical Nutrition, 70, 1040 -1045.


Inoue, H., Kobayashi-Hattori, K., Horiuchi, Y., Oishi, Y. Arai, S., & Takita, T. (2006). Regulation of Body Fat Percentage in Developmental-Stage Rats by Methylxanthine Derivatives in a High-Fat Diet. Bioscience Biotechnology & Biochemistry, 70(5), 1134-1139.


Lopez-Garcia, E., van Dam, R. M., Rajpathak, S., Willett, W.C., Manson, J.E., & Hu, F.B. (2006). The American Journal of Clinical Nutrition, 83, 674-680.


Panagiotakos, D.B., Pitsavos, C., Chrysohoau, C., Kokkinos, P., Toutouzas, P., & Stefanadis, C. (2003). The J-shaped effect of coffee consumption on the risk of developing acute coronary syndromes: The CARDIO2000 case-control study. The Journal of Nutrition, 133, 3228-3232.


Roberts, A. T., de Jonge-Levitan, L., Parker, C.C., & Greenway, F. (2005). The Effect of an Herbal Supplement Containing Black Tea and Caffeine on Metabolic Parameters in Humans. Alternative Medicine Review, 10(4), 321-325.


Santalla, A., Lucia, A., & Perez, M. (2001). Caffeine Ingestion Attenuates the VO2 Slow Component During Intense Exercise. Japanese Journal of Physiology, 51(6), 761-764.


Shimoda, H., Seki, E., & Aitani, M. (2006). Inhibitory effect of green coffee bean extract on fat accumulation and body weight gain in mice. BMC Complementary and Alternative Medicine, 6(9),


Straub, Richard O. (2007). Health Psychology: A Biopsychosocial Approach Second Edition. Worth Publishers. New York, NY. 28;199;230.


Westerterp–Plantenga, M., Lejeune, M.P., & Kovacs, E.M.R. (2005). Obesity Research, 13(7), 1195-1204.



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