The use of the "ECA Stack" - ephedrine, caffeine and aspirin - has been common-place in body-building and weight-loss circles. (e.g. in 1999, 2% of the Danish population and 12 million US inhabitants were using some variant. [Ref]

It is purported to hasten the reduction of body fat and increase athletic performance. After doing some research I can't even find a consistent claim for how this could work.

I can see that ephedrine could could reduce body fat (because ephedrine behaves similarly to amphetamines in this regard), but I cannot see how it could increase athletic performance.

Is there any science behind this claim? Are there any suggestions about the mechanism?

2 Answers 2


It appears that the combination of ephedrine and caffeine may have a positive effect on athletic performance.

From this AMA study on ephedrine:

Efficacy: Athletic Performance

We found 8 published controlled trials of the effects of synthetic ephedrine on athletic performance; most were crossover designs and all but 1 also included caffeine. One study assessed the effect of ephedrine and exercise training on basal metabolic rate, did not report athletic performance outcomes, and is not described below.​ The remaining 7 trials were not appropriate for pooled analysis because they involved different types of exercise (power and endurance) and different outcome measures, so they are discussed here individually. We found no trials assessing the effects of herbal ephedra on athletic performance.

Six trials by Bell and colleagues assessed the exercise capacity of small groups of healthy male participants (all trials included 24 participants or fewer) and are summarized in Table 2. These trials reported that neither caffeine nor ephedrine alone had significant effects on parameters of exercise performance such as oxygen consumption, time to exhaustion, or carbon dioxide production, but the combination of ephedrine and caffeine consistently demonstrated a 20% to 30% increase in performance. The single trial of strength training did show an improvement in muscle endurance but only on the first of 3 repetitions. In the only trial to test the effects of ephedrine and caffeine on thermal regulation, no increase in temperature was reported. Nausea and vomiting were reported in a third of the participants given ephedrine at a dose of 1 mg/kg with 5 mg/kg of caffeine, but not in any of those given a lower dose of 0.8 mg/kg of ephedrine and 4 mg/kg of caffeine.

It should be noted that these trials had very low numbers of participants, and the results should be deemed plausible.


I first did a search for 'medical research search engine' and found several.

One of those was MedScape, which came up with the result:

Transient Blindness Due to Posterior Reversible Encephalopathy Syndrome Following Ephedra Overdose

Extreme used in the presented patient.1 Both supplements are based on the ECA stack containing ephedrine, caffeine and aspirin which are used for their ...

Reading the article, the reference to ECA stack states:

Both supplements are based on the ECA stack containing ephedrine, caffeine and aspirin which are used for their synergistic thermogenic properties.[4]

Which references the paper:

Daly PA, Krieger DR, Dulloo AG, et al. Ephedrine, caffeine and aspirin: safety and efficacy for treatment of human obesity. Int J Obes Relat Metab Disord 1993;17(suppl 1):S73-S78.

So, perhaps this paper would contain what you are looking for or you could even try contacting Krieger or Dulloo.

A search on pogofrog for 'ECA stack' turned at least one interesting result:

ISSN Exercise & Sport Nutrition Review: Research & Recommendations

J Int Soc Sports Nutr. 2004; 1(1): 1–44.

Published online 2004 May 10. doi: 10.1186/1550-2783-1-1-1.

PMCID: PMC2129137

Richard B Kreider,corresponding author1 Anthony L Almada,2 Jose Antonio,3 Craig Broeder,4 Conrad Earnest,5 Mike Greenwood,1 Thomas Incledon,6 Douglas S Kalman,7 Susan M Kleiner,8 Brian Leutholtz,1 Lonnie M Lowery,9 Ron Mendel,10 Jeffrey R Stout,11 Darryn S Willoughby,1 and Tim N Ziegenfuss10

which referenced several research papers on the ECA Stack which may provide a lead to a scientist who can provide the answer you seek.

This, perhaps, isn't the answer you want, but it may lead to you the answer.

  • That may not be the immaculate answer, as you say, but it's the closest I've ever seen to a useful lead on this topic. Thanks! Commented Mar 6, 2011 at 10:46

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