ECA Stack For Weight Loss

Nutrition Coach Weighs In Dosage, Safety, and Efficacy

By: Jeremy Fox, CNC, CPTPublished: May 5, 2021

The weight loss supplement industry is big business. And I’m sure you see ads for weight loss products every day. But the honest truth is that the vast majority simply don’t work.

On the other hand, the ECA stack is arguably the most effective fat-burning compound ever discovered. Yet, it’s not widely advertised or marketed. The reason has to do with controversy around its ingredients.

In this article, I break down what the ECA stack is and how it can help you burn fat. More importantly, I shed some light on its side effects and safety concerns so you can decide if it’s worth adding to your weight loss plan.

ECA Stack

Please keep in mind, this article is not medical or weight loss advice. It is for information purposes only. Talk to your doctor before taking any new medications or supplements.

What Is The ECA Stack?

ECA stands for ephedrine, caffeine, and aspirin. When used together, the combination is called a stack. The main reason people use the ECA stack is to increase the rate of fat burning during a diet.

Before we get into how it works, let me explain a little more about each ingredient.


Ephedrine is a potent stimulant of the central nervous (CNS) derived from the Ephedra plant. It’s primarily used in medicine as a decongestant and to treat breathing problems.

As a stimulant, ephedrine works by increasing norepinephrine1. A hormone that activates the sympathetic nervous system, also known as the fight or flight response. Therefore it mobilizes the brain and body for action. 

It may also stimulate brown fat thermogenesis2, which is associated with an increased metabolic rate.

Ephedra vs Ephedrine

Ephedra sinica is a shrub native to China and Mongolia that contains compounds referred to as ephedra alkaloids. Of which ephedrine is the alkaloid most responsible for the thermogenic effects.

Supplements containing ephedra herbs have been banned due to issues regulating the amount of ephedrine contained in them. But pharmaceutical-grade ephedrine is still widely available. 

I’ll cover this in more detail in the section on the legal status of ephedrine.

ECA Stack Ephedrine Molecule


Caffeine is another CNS stimulant most commonly found in coffee and tea. It’s mainly used to make you feel more awake.

As a stimulant, caffeine works by inhibiting the degradation of intracellular cyclic AMP (cAMP) and delaying fatigue1.


Aspirin is a common nonsteroidal anti-inflammatory drug (NSAID) and blood thinner. It can treat pain, fever, headache, and inflammation. Sometimes used to reduce the risk of a heart attack.

The role of aspirin in the ECA stack is to prolong the rise in norepinephrine. But this may not be necessary and aspirin is not needed to burn fat.

In addition, it is not recommended to take aspirin on a daily basis unless directed by your doctor. Even low-dose aspirin can have unwanted side effects.

ECA Stack Dosage

In clinical studies, the dosage of ephedrine and caffeine is 20-30 mg and 100-200 mg respectively. Very few studies used aspirin at all. The ephedrine and caffeine were taken 3 times daily about 3-4 hours apart.

It’s best to start taking it first thing in the morning and stop taking it at least 4 hours before bedtime to avoid restless sleep. Also, taking it with food helps prevent jittery feelings.

For smaller individuals or those sensitive to stimulants, it’s wise to start with half the recommended dose. So 10-15 mg ephedrine and 50-100 mg caffeine. And limit doses to 1-2 per day to test the effects.

How Does The ECA Stack Work?

Separately, each ingredient has little to no effect on weight loss. But there is an apparent synergistic effect, particularly with ephedrine and caffeine.

While the exact mechanisms of action are quite complicated, researchers believe ephedrine and caffeine increase energy expenditure, decrease appetite, and spare lean muscle.

Increases Metabolic Rate

One way the ECA stack promotes weight loss is through thermogenesis. This is the process of heat production that results in burning more calories at rest. In other words, it increases your resting metabolic rate (RMR).

Researchers found that a combination of ephedrine and caffeine resulted in an 8% increase in 24-hour energy expenditure in obese adults3. That may not sound like much, but it could equate to 100-200 calories that you otherwise wouldn’t burn.

A separate study showed that aspirin did not further increase the thermogenic effect of ephedrine and caffeine4. Although the measurement ended after about 3 hours.

Prevents Loss Of Lean Mass

Another way the ECA stack may help you lose weight is by mitigating the muscle loss that occurs with calorie-restricted diets. Studies show that participants taking ephedrine and caffeine lose less muscle while dieting compared to the control groups5.

ECA Stack Fat Loss

Two groups of obese women following a 1,000 calorie per day diet both lost 20 lbs in 8 weeks. But the group that took ephedrine and caffeine lost 10 lbs more fat and 6 lbs less lean mass. Adapted from Astrup, Arne, et al.

Furthermore, preserving lean mass while dieting also maintains your metabolic rate. This means you continue to burn more calories at rest, helps you lose additional weight and keep it off.

Decreases Appetite

Finally, the appetite suppressing effect of ephedrine and caffeine could be a third way in which it can help you lose weight. When you don’t feel as hungry during a diet, it’s easier to stick to your plan and get results.

ECA Stack Results

The ECA stack has multiple potential benefits including weight loss, increased exercise capacity, and even a cognitive boost. But I know you’re most interested in weight loss, so I’ll start with that.

Weight Loss

A review of dozens of studies showed that, on average, ephedrine plus caffeine was associated with a statistically significant weight loss of 2.2 pounds/month more than the placebo6.

One such study involved two groups of young obese people eating 500 fewer calories than they burned each day. After 20 weeks, the ephedrine and caffeine group lost nearly 18 lbs while the placebo group lost less than 1 lb7.

ECA Stack Fat Loss

The difference in weight loss between two groups of young people following the same diet. Adapted from Molnar, et al.

Another study did not restrict the participant’s calorie intake at all. Still, the group that took EC lost an average of 6 lbs in 8 weeks compared to 2 lbs for the placebo group8. Of course, you will get better results when combined with optimal diet and exercise.

Athletic Performance

In addition to weight loss, some athletes use the ECA stack as an ergogenic aid. Ephedrine is a bronchodilator, which means it opens airways and makes it easier to breathe. This should help improve aerobic exercise performance.

Also, the stimulatory effects of ephedrine and caffeine could boost anaerobic performance. One study reported significant increases in the number of repetitions weight lifters completed for both the leg press and bench press exercises9

Researchers concluded that this performance boost is likely a result of both the stimulation of the CNS by ephedrine and of the skeletal muscle by caffeine10.

Mental Focus

Lastly, ephedrine and caffeine are sometimes used by college students and people trying to improve mental concentration. While there are limited studies, the alpha-agonist properties of ephedrine are associated with increased mental focus.

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Is The ECA Stack Safe?

If you’re wondering how the ECA stack can be so effective yet not be widely acknowledged or promoted, the main reason is concerns regarding its safety.

Again, it’s important to realize, ephedrine is a powerful stimulant that temporarily increases heart rate and blood pressure. Therefore if you have a pre-existing risk for cardiac issues or an irregular heartbeat, you shouldn’t take it.

In addition, ephedrine and caffeine stimulate the sympathetic nervous system’s fight or flight response. So if you have anxiety or panic attacks, it could make that worse.

However, no serious adverse events (death, heart attack, stroke, seizure, or serious psychiatric events) were reported in any clinical trials8. While mild side effects were temporary or subsided after a few weeks.

ECA Stack Side Effects
  • Elevated heart rate
  • Increased systolic blood pressure (top number)
  • Dizziness
  • Tremor
  • Insomnia

For healthy individuals, ephedrine and caffeine are considered relatively safe. While there are no studies in which ephedrine/caffeine directly caused cardiac or psychiatric events, it does increase the risk, particularly if used incorrectly.

So use common sense. And as with any drug or medication, you should always consult your doctor before using ephedrine.

Is Ephedrine Legal?

Another issue with the ECA stack, and ephedrine, in particular, is the legality. In 2004, the US Food & Drug Administration (FDA) banned ephedra-containing dietary supplements due to reports of adverse effects.

In addition, many major sports organizations ban the use of ephedra and ephedrine. Including the MLB, NBA, NFL, NCAA, and Olympics.

However, ephedrine is still legal in many applications outside of dietary supplements. And can be sold as an over-the-counter nasal decongestant or bronchodilator where the dosages are more tightly controlled.

To add to the confusion, the US passed an amendment further restricting the sale of ephedrine-containing products in 2005. This was due to the fact that it can be used as an ingredient to make methamphetamines.

For this reason, ephedrine must be stored behind the pharmacy counter or in a locked cabinet and requires proof of identity to limit the quantity per person. Although these restrictions vary by state and country.

Related: Ibutamoren MK-677 Safety and Legality

How To Buy The ECA Stack

First, beware of any dietary supplements being marketed as ECA. Legally, they can’t contain ephedra or ephedrine. So they’re just trying to cash in and take advantage of people looking for the ECA stack.

Second, despite all the red tape, you can still purchase ephedrine at your local pharmacy in the form of a bronchodilator. Two of the most common brands are Bronkaid and Primatene.

The main difference is that Bronkaid contains ephedrine sulfate in single 25 mg tablets. Whereas Primatene contains ephedrine HCL in 12.5 mg tablets.

Sulfate and HCL contain slightly different concentrations at 77% and 82% respectively. Which comes out to 19.25 and 20.5 mg of pure ephedrine per 25 mg dose. So if you want more potent ephedrine, go with Primatene.

ECA Stack Ephedrine

Simply walk up to the counter and ask for it by name and be prepared to show your driver’s license. In some states, you are limited to two boxes at a time. But that lasts for 3 weeks when taking the recommended dosage.

Caffeine can also be purchased at the pharmacy in the form of 200 mg tablets. This is nice if you plan on taking that amount because it’s precisely measured out. Although caffeine from other sources, such as coffee, works just as well.

ECA Stack Caffeine

In terms of cost, ephedrine runs about $10 per box and caffeine is a few bucks a bottle. So that adds up to about $30 per month, which is the same or less than typical weight loss supplements.

But compared to other fat burners, ephedrine and caffeine actually produce significant results. So the cost to result ratio is much better in favor of EC.

Final Thoughts

Over the years, I’ve read hundreds of medical studies evaluating dozens of weight loss supplements. And I’ve not come across something with more definitive and significant effects than the combination of ephedrine and caffeine.

In my opinion, the controversy regarding its safety has been overblown by the media, which has led to bans and restrictions. Most incidents are the result of either misuse or a combination of other significant medical conditions.

That being said, the risks are still real. And, as I’ve said numerous times, it’s always a good idea to talk to your doctor before taking any new supplements or medications. Particularly if you’re already taking other medications or have underlying health issues.

At the end of the day, I am not advising you to take or avoid the ECA stack. I’m simply providing you with the most complete information. It’s up to you to weigh the risks and benefits based on your health and situation.

If you do choose to use the ECA stack, make sure you read and follow instructions on the labels. And don’t rely on supplements and drugs to get results. Approach weight loss from a holistic point of view and include proper diet and exercise.

For more helpful information on all things related to supplements, diet, and exercise, check out my related content below!

1) Diepvens, Kristel, Klaas R. Westerterp, and Margriet S. Westerterp-Plantenga. “Obesity and thermogenesis related to the consumption of caffeine, ephedrine, capsaicin, and green tea.” American journal of physiology-Regulatory, integrative and comparative physiology (2007).
2) Bukowiecki, L., L. Jahjah, and N. Follea. “Ephedrine, a potential slimming drug, directly stimulates thermogenesis in brown adipocytes via beta-adrenoreceptors.” International journal of obesity 6.4 (1982): 343-350.
3) Dulloo, A. G., and D. S. Miller. “The thermogenic properties of ephedrine/methylxanthine mixtures: human studies.” International journal of obesity 10.6 (1986): 467-481.
4) Horton, T. J., and C. A. Geissler. “Post-prandial thermogenesis with ephedrine, caffeine and aspirin in lean, pre-disposed obese and obese women.” International journal of obesity and related metabolic disorders: journal of the International Association for the Study of Obesity 20.2 (1996): 91-97.
5) Astrup, Arne, et al. “The effect of ephedrine/caffeine mixture on energy expenditure and body composition in obese women.” Metabolism 41.7 (1992): 686-688.
6) Shekelle, Paul, et al. “Ephedra and ephedrine for weight loss and athletic performance enhancement: clinical efficacy and side effects.” Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. Centre for Reviews and Dissemination (UK), 2003.
7) Molnar, D., et al. “Safety and efficacy of treatment with an ephedrine/caffeine mixture. The first double-blind placebo-controlled pilot study in adolescents.” International Journal of Obesity 24.12 (2000): 1573-1578.
8) Daly, Patricia Ann, et al. “Ephedrine, caffeine and aspirin: safety and efficacy for treatment of human obesity.” International journal of obesity and related metabolic disorders: journal of the International Association for the Study of Obesity 17 (1993): S73-8.
9) Jacobs, Ira, H. A. R. L. E. Y. Pasternak, and Douglas G. Bell. “Effects of ephedrine, caffeine, and their combination on muscular endurance.” Medicine and science in sports and exercise 35.6 (2003): 987-994.
10) Bell, Douglas G., I. R. A. Jacobs, and K. R. I. S. T. I. N. A. Ellerington. “Effect of caffeine and ephedrine ingestion on anaerobic exercise performance.” Medicine and science in sports and exercise 33.8 (2001): 1399-1403.

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