This is from an article written by Stephen Schmitz, MD, MPH
and Bruce Kneller, BSN-RN. All credit should go to them
Aspirin
"Aspirin {salicyclic acid acetate} and it's naturally occurring methyl ester (methyl salicylate)-- found in the leaves of Gaultheria procumbrens and on the bark of Betula lenta-- have long been used as analgesics, anti-inflammatories, antipyretics and recently as anti-coagulants. The "A" portion of ECA, aspirin has been thought of potentiating the thermogenic and lipolytic properties of both ephedrine and caffeine. Recent research seems to contradict this however. At a study at The University of London's Department of Nutrition and Dietetics, 40 women (20 non-obese and 20 obese) were given either ephedrine and caffeine (30 mg and 100 mg) or ephedrine, caffeine and aspirin (30 mg, 100 mg, and 300 mg) post prandially (1050 kJ liquid meal). Using indirect calorimetry, observations were made in all groups every 30 minutes for 160 minutes. There was no significant differences between the groups that received aspirin and the groups that did not. We conclude that aspirin does not potentiate the acute thermic effect of ephedrine and caffeine.6
In another study conducted at King's College in London, it was demonstrated that aspirin does not potentiate the thermogenic response to ephedrine in lean women and only slightly so in obese women.7 The increase seen in this study represented a 1.2 kcal per hour increase in metabolism for lean women and a 2.4 kcal per hour increase in metabolism in obese women over use of ephedrine alone, which over an entire week, would represent less than one ounce of bodyweight. We feel that this is insignificant.7
Based on these two studies, we feel that aspirin and its analogs do not play a substantial role in inducing or increasing thermogenesis and/or lipolysis but they do have the potential to induce SAEs when consumed over long periods of time (e.g. ulceration of the stomach and increases in bleeding times). Therefore, we feel that aspirin and it's analogs should not be used in any thermogenic/lipolytic stack."
6) Horton TJ, Geissler CA. Post-prandial Thermogenesis with Ephedrine, Caffeine and Aspirin in Lean, Predisposed Obese and Non-obese women. Int J Obes Relat Metab Disorder, 1996 Feb;20(2):91-95.
7) Horton TJ, Geissler CA. Aspirin Potentiates the Effect of Ephedrine on the Thermogenic Response to a Meal in Obese but not Lean Women. Int J Obes, 1991 May;15(5):359-366.
Most of the arguements that people make for aspirin state that aspirin extends the thermogenic effects of ephedrine by inhibiting the enzyme cyclooxygenase and therefore decreasing prostaglandin synthesis (why aspirin is an anti-inflammatory). This helps combat one of ephedrine's effects. Ephedrine stimulates the release of norepinephrine, which stimulates the release of adenosine and the synthesis of prostaglandins by the activated tissue. Since aspirin inhibits the synthesis of prostaglandins (1), it is believed it enhances the effect of norepinephrine (the reason why caffeine is included in the stack to combat adenosine). By increasing the amount of norepinephrine one would expect to increase lipolysis. Caffeine achieves this, however in actual studies aspirin as yet to prove the same. One can only hypothesize on why aspirin's effect on prostaglandins does not effect lipolysis.
There have been no studies that I am aware of that show that an ECA stack is more effective than an EC stack. The only studies that have been proven to work are when an ECA stack has been done in a study against a placebo. Couple this information with the effects aspirin has on the stomach (nausea, heartburn, and sometimes bleeding ulcers) one could conclude that the most effective stack would be just Ephedrine and Caffeine.
1. Rawson ES, Clarkson PA. Ephedrine as an ergogenic aid. Performance-enhancing Substances in Sport and Exercise. Ed Bahrke MS, Yesalis CE. Human Kinetics. 2002.
Please Scroll Down to See Forums Below 
