Thermogenics And Calorie Burning: Is It The Caffeine?

Pick up any thermogenic product and I am willing to bet that it contains caffeine. Caffeine or caffeine-containing botanicals, are often formulated into weight loss products. Here's the latest...

Thermogenics & Calorie Burning: Is It The Caffeine?

Pick up any thermogenic product and I am willing to bet that it contains caffeine. Or maybe it contains mate, guarana, kola nut, cacao or green, black or white tea, or a combination of any of these ingredients (all of which are botanical sources of caffeine)1.

Caffeine (naturally occurring or added synthetic caffeine2,3,4) or caffeine-containing botanicals, are often formulated into weight loss products because caffeine increases both lipolysis (the breakdown of fat) and thermogenesis (calorie burning) for a period of time after ingestion.

Back in the day when ephedra dawned supplement store shelves, figure competitors and bodybuilders quickly discovered that the research-backed combination of ephedra + caffeine5 helped them shed any fat hiding their muscles prior to competition. Now that ephedra is pretty much out of the picture we are left with caffeine.

Caffeine plus a wide array of other ingredients that haven't been shown to do a whole lot by themselves but they sound good on the back of a bottle and may work synergistically with caffeine. And, there are a plethora of acute studies, indicating that immediately post-consumption, caffeine containing products temporarily increase thermogenesis6,7,8,9,10,11.

However, there are also a few studies that have been recently published or presented as abstracts indicating that products containing caffeine may also augment weight loss efforts if consumed daily. That's huge. And it's new research.

EliteFx's Celsius Vs Diet Coke

EliteFx, the makers of the CelsiusTM have dumped some money into research trials examining whether it can hold it's own next to the various weight loss supplements on store shelves. This product contains approximately 200mg caffeine in the form of guarana, green tea leaf (containing 10% ECGC) and ginger root along with B vitamins, vitamin C and calcium.

In one of the first studies on this beverage, they compared it to Diet Coke® (about 45 mg caffeine). Twenty college students came into the lab, drank either the Diet Coke® or CelsiusTM and the researchers measured the change in their metabolism over a 3-hour period. Then they did the exact same study again and switched the groups so the college kids drinking the CelsiusTM got the Diet Coke® and vice versa.

After looking at the results from both trials, the researchers found that Diet Coke® did raise metabolism just a little but, CelsiusTM significantly raised metabolism for the three hours post-consumption12. It could be the caffeine or it could be the caffeine + green tea, either way, it seems to work.

Green tea has two thermogenic components, caffeine and EGCG. Though researchers aren't completely sure how green tea works, they know the catechin polyphenols (like EGCG), help boost circulating norepinephrine which increases the breakdown of stored fat and stored carbohydrates13.

After the first few studies looking at what affect CelsiusTM had on metabolism right after consumption, they examined whether it would help increase weight and fat loss over time (28 days).

In this study they took sedentary, slightly overweight men and women and put them on a supervised endurance and resistance training program. One group consumed the new product 15 minutes prior to working out on training days and whenever they wanted to on non-training days.

The endurance and resistance training program worked because both groups lost fat (that's a good thing). However, only the CelsiusTM group saw a significant change in fat free mass (muscle) and this group also lost a significantly greater amount of fat mass14. So it seems that consuming this beverage daily may augment the positive physique changes associated with an endurance and resistance training program.

Caffeine From Coffee

If you prefer coffee, a coffee company called Javalution has created functional coffees including JavaFit Diet and JavaFit Energy Extreme. The first version of JavaFit Energy Extreme (450 mg caffeine, 360 mg citrus aurantium, 1200 mg garcinia cambogia, 225 mcg chromium polynicotinate) may have had you jumping through the roof if you were not used to consuming that much caffeine (a Starbucks venti Caffe Mocha made with espresso has 180 mg caffeine by comparison), but it did increase calorie burn post consumption and in comparison to regular coffee15.

The current version of JavaFit Energy Extreme (a different formula than the aforementioned study; it contains just 62 mg added caffeine, green tea extracts, niacin, garcinia cambogia) has also been found to increase calorie burn, for up to 3 hours, post consumption16. Look for additional research coming out soon on JavaFit Diet Plus and weight and fat loss over time.

Caffeine From Supplements

As far as supplements, a particular supplement containing tyrosine, capsaicin, catechines and caffeine (unknown quantity) was found to slightly increase fat loss in obese subjects on a low caloric diet over a period of 8 weeks17. All of these studies mentioned here show promise for caffeine and thermogenic supplements to enhance weight loss and fat loss.

A few interesting tidbits about caffeine:

  • Within 45 minutes after ingestion, caffeine is completely absorbed by the body18.
  • The total time it takes to eliminate caffeine completely depends upon many factors such as age and various aspects of one's health. In healthy individuals at least half of the total caffeine consumed at a given time is eliminated in approximately 3 to 4 hours19.
  • We adapt to the amount of caffeine we regularly consume by increasing the number of receptor sites that caffeine binds to in our central nervous system so we end up needing more caffeine over time to achieve the same stimulatory affect we felt when we initially started taking caffeine20.

The Central Nervous System

The human central nervous system consists of the brain and spinal cord. These lie in the midline of the body and are protected by the skull and vertebrae respectively.

This collection of billions of neurons is arguably the most complex object known.

The central nervous system along with the peripheral nervous system comprise a primary division of controls that command all physical activities of a human.

Neurons of the central nervous system affect consciousness and mental activity while spinal extensions of central nervous system neuron pathways affect skeletal muscles and organs in the body.

  • If habitual caffeine consumers reduce their caffeine intake, they get headaches, may be irritable and may initially feel like they aren't concentrating as well. Once the number of receptor sites decreases, these withdrawal symptoms will decrease as well20.

There are a number of caffeine containing products on the market including drinks such as CelsiusTM (approximately 200 mg caffeine in a 12 oz bottle) and JavaFit coffee and, if you prefer to take your caffeine on the run in pill form, Lean System 7 by Isatori, Hot-Rox Extreme and Hydroxycut are just a few of the choices you have.


Though caffeine may help augment your weight loss efforts, don't expect to go from a size 22 to a size 4 by increasing your caffeine intake alone. And, though caffeine is considered Generally Recognized as Safe (GRAS)21 and has been consumed for hundreds of years, every person's tolerance to caffeine differs, and, caffeine may be unsafe for some people when consumed in high doses, especially over long periods of time.

Those with any particular health problems should talk to their physician first before bumping up their caffeine intake. And if you are on any particular medicine that may interact with caffeine (such as diethylpropion, phentermine, pseudoephedrine, epinephrine26,27, clozapine28, riluzole29) also talk to your doctor first.

Doses of 250 to 300 mg or more per day may result in other unwelcome health problems. Pregnant women should definitely keep their caffeine consumption below 300 mg per day30,31. And like anything (including water in the absence of adequate electrolytes), too much isn't good.

Ingesting approximately 10 to 14 grams of caffeine (150-200 mg/kg body weight) can cause death.32 But again, normal caffeine consumption shouldn't harm a healthy person, and it make even make you concentrate better, stay awake during a boring meeting and possibly, help you show off those abs you've worked so hard for.

  1. Newall CA, et al. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Politte J. How'd They Do That? Making Decaf Coffee. American Chemical Society.
  3. The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.
  4. M. Sittig. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd ed. Noyes Publications, Park Ridge, NJ. 1985.
  5. Boozer CN, et al. Herbal ephedra/caffeine for weight loss: a 6-month randomized safety and efficacy trial. Int J Obes Relat Metab Disord 2002;26(5):593-604.
  6. Dulloo AG, Geissler CA, Horton T et al. Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and postobese human volunteers. Am J Clin Nutr 1989;49(1):44-50.
  7. Astrup A, Toubro S, Cannon S et al. Caffeine: a double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers. Am J Clin Nutr 1990;51(5):759-67.
  8. Koot P, Deurenberg P. Comparison of changes in energy expenditure and body temperatures after caffeine consumption. Ann Nutr Metab. 1995;39(3):135-42.
  9. Dulloo AG, Duret C, Rohrer D et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr 1999;70(6):1040-5.
  10. Greenway FL, et al. Effect of a dietary herbal supplement containing caffeine and ephedra on weight, metabolic rate, and body composition. Obes Res 2004;12(7):1152-7.
  11. Belza A, Toubro S, Astrup A. The effect of caffeine, green tea and tyrosine on thermogenesis and energy intake. Eur J Clin Nutr. 2007 Sep 19; [Epub ahead of print]
  12. Mendel RW, Hofheins JE. Metabolic responses to the acute ingestion of two commercially available carbonated beverages: A pilot study. J Int Soc Sports Nutr 2007;4:7.
  13. Kao Y, Hiipakka R, Liao S. Modulation of endocrine Systems and Food Intake by Green Tea Epigallocatechin Gallate. Endocrinology 141(3):980-987; 1999.
  14. Jeffrey R. Stout, FISSN, Jordan R. Moon, Sarah E. Tobkin et al. Pre-workout consumption of Celsius? enhances the benefits of chronic exercise on body composition and cardiorespiratory fitness. Poster presentation, 5th Annual ISSN conference. June 2008.
  15. Hoffman JR, Kang J, Ratamess NA et al. Thermogenic Effect from Nutritionally Enriched Coffee Consumption. J ISSN 2006;3(1):35-41.
  16. Taylor LW, Wilborn CD, Harvey T et al. Acute effects of ingesting Java FitTM energy extreme functional coffee on resting energy expenditure and hemodynamic responses in male and female coffee drinkers. JISSN 2007;4:10.
  17. Belza A, Frandsen E, Kondrup J. Body fat loss achieved by stimulation of thermogenesis by a combination of bioactive food ingredients: a placebo-controlled, double-blind 8-week intervention in obese subjects. Int J Obes (Lond) 2007;31(1):121-30.
  18. Newton R, et al.Plasma and salivary pharmacokinetics of caffeine in man. Eur J Clin Pharm 1981;21(1): 45-52.
  19. Physician's Drug Handbook; 11th edition. Lippincott Williams & Wilkins. 2005, Philadelphia, PA
  20. Juliano LM. A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features. Psychopharmacology 2004;176(1):1-29.
  21. FDA. Center for Food Safety and Applied Nutrition, Office of Premarket Approval, EAFUS: A food additive database. Available at:
  22. Smith A. Effects of caffeine on human behavior. Food Chem Toxiocol 2002;40:1243-55.
  23. Cannon ME, et al. Caffeine-induced cardiac arrhythmia: an unrecognised danger of healthfood products. Med J Aust 2001;174:520-1.
  24. Avisar R, et al. Effect of coffee consumption on intraocular pressure. Ann Pharmacother 2002;36:992-5.
  25. Nurminen ML, et al. Coffee, caffeine and blood pressure: a critical review. Eur J Clin Nutr 1999;53:831-9.
  26. Haller CA, Benowitz NL. Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids. N Engl J Med 2000;343:1833-8.
  27. Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at:
  28. Hagg S, et al. Effect of caffeine on clozapine pharmacokinetics in healthy volunteers. Br J Clin Pharmacol 2000;49:59-63.
  29. Sanderink GJ, et al. Involvement of human CYP1A isoenzymes in the metabolism and drug interactions of riluzole in vitro. Pharmacol Exp Ther 1997;282:1465-72.
  30. Klebanoff MA, et al. Maternal serum paraxanthine, a caffeine metabolite, and the risk of spontaneous abortion. N Engl J Med 1999;341:1639-44.
  31. Fernandes O, et al. Moderate to heavy caffeine consumption during pregnancy and relationship to spontaneous abortion and abnormal fetal growth: a meta-analysis. Reprod Toxicol 1998;12:435-44.
  32. Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at: