Updated: 01/14/2018

Diet products either work or they don’t. Period. Let’s find out which one Stacker 2 is. We looked at the ingredients, side effects, customer service and clinical research. Furthermore, we examined hundreds of user reviews and comments. Then, we summarized and condensed to give you the bottom line.

Stacker 2 Readers: Click here to find out why we're giving away samples of our product, Burn HD.

What is Stacker 2?

First off, Stacker 2 is a fat burner using the principles of the infamous ECA Stack. [1] The ingredients are yerba mate, green tea, guggulsterone, cassia mimosoides, white willow bark [2] and caffeine 200mg. You’ll take one to three per day after meals. The blister pack makes it easy to take with you on-the-go. Supposedly, this formula promotes weight-loss by boosting energy levels and metabolism. [3]

Stacker 2 was brought to the market more than 20 years ago by NVE Pharmaceuticals. It’s available in at local stores and through the official website. We like it contains a few natural ingredients and it appears to be affordable, but read on…

Stacker 2 Side Effects – “Look Out?”

The first concern was the intensity of Stacker 2 side effects. “This one contains multiple fat burners,” said our Research Editor.  “While they’re supposed to boost metabolism, there’s a chance you could experience adverse reactions.” [4]

“I noticed it also made me jittery and sometimes gave me a headache,” said one user.

“Even after doing intensive workouts I still had too much energy. I had to stop taking them, because occasionally I had caffeine crashes. [5] They are not fun at all,” offered another.

Side effects are rare, so we found some users that didn’t experience adverse reactions.

“No headache, jitters or anxiety like other caffeine pills,” commented a dieter. [6]

Stacker 2 Customer Testimonials

Results – “No Weight-Loss!”

Based on some Stacker 2 reviews, there’s were customers that didn’t notice results. “I did not experience any weight loss on this product. I did have more energy but I was looking for a fat burner,” said one customer online.

“The pill does give a great amount of energy, but the claim of it being a fat burner is bogus,” said a user.

Upon reading further reviews, some customers noticed results. “I tried them again and they helped me lose weight [7],” explained a customer.

“After the first one, I felt warm and could tell my metabolism was increasing,” stated another.

Our research has shown if there is some particular part of a diet supplement that’s troublesome, like not producing results, the likelihood of long-term success is slim. If Stacker 2 doesn’t help you lose weight or burn fat, is it really worth it?

The Science – “Legitimate?”

Some of the Stacker 2 ingredients have been clinically verified to work. The white willow bark extract [8], green tea extract and kola nut [9] are common ones that have been shown to be mildly effective. However, the any results aren’t connected to this formula. We at DietSpotlight find clinical research to be important to the review process. When there’s no solid-science used to support the claims, we have concerns.

What Users Are Saying

“I love this product. It gives me energy and helps to suppress my appetite.”

“Just like normal stackers from the packs they mostly help for people trying to stay away from the fizzy energy drinks.”

“I did not experience any weight loss on this product. I did have more energy but I was looking for a fat burner. Decent product though for energy but I’d rather have just caffeine.”

Also: read our Burn HD Weight-Loss Kit review »Stacker 2 Ingredients

The Bottom Line – Does Stacker 2 Work?

Will Stacker 2 help you lose weight? Well, we like that it contains  few natural ingredients and that we found some positive customer comments, but the lack of research showing it works is concerning. Also, reports of negative side effects and no real results leaves us a bit skeptical about giving it the thumbs up.

If you are still in the market for an effective fat burner, we suggest going with one that’s clinically proven to work, without any mentions of harmful side effects.

Among the best products we’ve seen this year is our product called Burn HD. The formula contains four ingredients, clinically-tested, with results often located in The American Journal of Clinical Nutrition and the Journal of Medicine.

We’re so confident in our supplement, that we’re offering a 2-Week Sample, which is a good sign.

Learn More About Burn HD »
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Stacker 2

What are the side effects of Stack 2?

According to user comments, Stacker 2 side effects may include anxiety, nervousness, jitteriness, increased heartrate, irritability, sleeplessness, upset stomach, headaches and shortness of breath.

What are the ingredients in Stacker 2?

Stacker 2 ingredients are yerba mate, caffeine, green tea leaves, guggulsterone, cassia mimosoides extract and white willow bark.

How do I know if Stacker 2 is right for me?

Choosing the right product is the #1 question asked by DietSpotlight readers. We recommend trying any product before buying it and know that finding a product with a sample offer is near impossible - so we created our own product, Burn HD, with scientifically backed ingredients.

Click here to get your sample of our powerful fat burner today.

Does Stacker 2 work?

There’s no scientific research backing the effectiveness of Stacker 2. We found studies linking green tea and caffeine to weight-loss, but nothing specific to this formula.

How much does Stacker 2 cost?

Stacker 2 costs $19.99 on the official website.

How should I take Stacker 2?

You should take one Stacker 2 capsule, three times per day. Each bottle contains 100 capsules or about a 30-day supply. The company recommends not exceeding three pills per day.

If I take more Stacker 2, will I improve results?

No, you will not improve results if you take more Stacker 2.

How much caffeine is in Stacker 2?

Each serving of Stacker 2 contains 200mg of caffeine.

Does Stacker 2 come with a guarantee?

There’s no mention of a guarantee with Stacker 2.

Stacker 2 Ingredients

Stacker 2 carries one of those names that's been around for more than a decade. Stacker was once a popular ephedra supplement, but has since expanded the line and eliminated ephedra. You can choose from energy shots, Swarm, Yellow Hornet, Black Jax, and more.

Stacker 2 Ingredients and Supplement Facts

Serving Size: 1 Capsule
Serving Per Container: 100
Amount per Serving% DV
Proprietary Blend267mg*
- Yerba Mate**
- Green Tea Leaves**
- Guggulsterone**
- Cassia Mimosoides Extract**
- White Willow Bark**

Other Ingredients: Gelatin, stearic acid, magnesium stearate, titanium dioxide, dibasic calcium phosphate, microcrystalline cellulose

We really researched Stacker 2 ingredients to help you fully understand the specifics.

Yerba Mate (leaves)

Sometimes called green mate or hervea, yerba mate is a plant that’s often used to make beverages. It’s quite popular in certain parts of South America. It’s also used in various energy drinks sold in the US. It provides some caffeine, as well as vitamins and antioxidants.

What is it Supposed to Do?

Well, yerba mate[1] is found in a number of weight-loss products. It’s typically claimed to boost energy levels, stimulate metabolism, enhance focus and elevate mood. These benefits are all linked to the caffeine in this herb.

Clinical Research

According to the National Institutes of Health, yerba mate has shown some promise in mice. One study revealed, “Yerba Mate has the ability to decrease the differentiation of pre-adipocytes and to reduce the accumulation of lipids in adipocytes, both of which contribute to a lower growth rate of adipose tissue, lower body weight gain, and obesity.” Therefore, “Yerba Mate can potentially be used to treat obesity and diabetes.”

Green Tea (leaves)

Herbal teas are commonly consumed around the world. This is especially true in Asia. Green tea is a variety that grows in regions such as China and Japan. It differs from black tea[2] because it’s unfermented.

What is it Supposed to Do?

First off, green tea contains both caffeine and EGCG (epigallocatechin gallate). Therefore it provides a stimulant and polyphenol. Together these components can help boost thermogenesis.

Clinical Research

Some clinical studies have shown the benefits of green tea on weight-loss. One study from the University of Maryland Medical Center says, “Clinical studies suggest that green tea extract may boost metabolism and help burn fat.” In fact, one study revealed, “The combination of green tea and caffeine improved weight-loss and maintenance in people who were overweight and moderately obese.”

Guggulsterone (whole plant)

Also called guggul or devadhupa, guggulsterone is actually made from tree sap. Specifically, it comes from the Commiphora mukul tree, which grows in India. Sometimes this ingredient is used to treat acne blemishes.

What is it Supposed to Do?

Guggulsterone is often claimed to stimulate the thyroid gland. It’s found in many weight-loss supplements. By causing the thyroid to produce more hormones, this can potentially increase the metabolism of fatty tissue.

Clinical Research

Unfortunately studies have shown that guggulsterone does not have much of an impact on weight-loss. For instance, WebMD states, “Research suggests that guggul does not affect body weight in overweight or obese people.” However, this plant extract has been shown to help treat acne breakouts.

One that’s caught our attention is one called Dietspotlight Burn. It contains clinically-tested ingredients and have been shown to work. Want to learn more about it; click above.

Stacker 2 Scientific Abstracts

Yerba Mate

Data taken from in vivo studies showed that Yerba Mate has the ability to affect intake of food, resulting in elevated levels of energy expenditure, most likely an outcome of increased basal metabolism within mice given Yerba Mate. In vivo results from Yerba Mate treatment on lipid metabolism included decreases in serum triglycerides, serum cholesterol and glucose concentrations within test mice that were given a high-fat diet. It was concluded that Yerba Mate could possibly be a helpful tool in the treatment of obesity as well as diabetes. [1]

Green Tea

There is well documented evidence from animal and in vitro studies which outline the underlying mechanisms and biological actions of green tea and its catechins. There are human studies showing that green tea can be utilized to treat metabolic syndrome like obesity, type 2 diabetes, and cardio vascular conditions. When consumed long-term, green tea catechins may be helpful in fighting against high-fat diet induced obesity as well as type 2 diabetes. This could, in turn, significantly decrease risks of cardiovascular disease. There needs to be further studies which conform to the international standards that focus on the clinical and pharmacological effects of the tea and its catechins in order to confirm its mechanisms of action. [2]


Guggulsterone blocked TNF-alpha-induced endothelial tissue factor protein expression as well as surface activity. This occurred in a concentration-dependant manner and dexamethasone failed to have an effect on TNF-alpha-induced tissue factor expression. Guggulsterone was found to improve the endothelial tissue factor pathway inhibitor, weakening plasminogen activator inhibitor-1 and impairing vascular cell adhesion molecule-1 protein. Guggulsterone was found to suppress TNF-alpha-induced tissue factor mRNA expression, even more so, it weakened the activation of p38 and MAP kinases JNK. In vivo studies showed guggulsterone suppressing tissue factor activity as well as photochemical injury induced thrombotic occlusion in the carotid arteries of mice. It was concluded that guggulsterone, in vivo, blocked tissue factor expression in vascular cells and thrombus formation. It weakened vascular smooth muscle cell activation, thus making it a novel therapeutic tool for treating inflammatory diseases linked with an elevated risk of thrombosis. [3]

White Willow Bark

Salicin is found within white willow bark. Salicin is a chemical which resembles aspirin (acetylsalicylic acid). This, mixed with the plant’s anti-inflammatory activities (flavanoids), makes the plant responsible for delivering pain-relief along with anti-inflammation. White willow seems to trigger a relief in pain a little slower than aspirin; however, its effects can last much longer. [4]


Previous Stacker 2 Review (Updated March 19, 2014):

What You Should Know about Stacker 2

Stacker 2 derives its name from the term "stack" or "ECA stack". ECA is an acronym for ephedrine, caffeine and aspirin. When "stacked" or combined correctly it is said to be a fat burner and energy booster. Originally, this product contained ephedrine. The ephedrine has been substituted with a combination of ingredients, called a Proprietary Formula, that supposed to work similar to ephedrine. The official website of NVE Pharmaceuticals, the maker of the product, sells only the ephedrine free version. Be aware that Stacker 2 with the ephedrine formula is still being sold on online stores all over the web.

The official NVE Pharmaceuticals website is attractive if you like flash and sexy videos. The company manufactures and markets a variety of weight loss products and energy drinks. To obtain product information much beyond an ingredients list one has to go elsewhere. The product is inexpensive, less than $20 for a hundred tabs, and available at discounts and in a variety of quantities. If it's a caffeine and energy you seek, you may want to take a look at Hydroxycut, known for it's fat burning ingredients, it's claimed to boost metabolism, endurance, energy levels, and best of all, weight loss.

List of Stacker 2 Ingredients

Kola Nut - The usual source of caffeine in stack formulas.

Yerba Mate - Rumored to help in weight loss, no quality evidence.

Cassia Mimosoides - As a lipase inhibitor it theoretically prevents the body from absorbing and storing fat.

White Willow Bark - The usual source of aspirin in stack formulas.

Caffeine Anhydrous - Mild thermogenic benefit and energy booster.

Green Tea - Proven fat burning and thermogenic benefits in sufficient quantities.

Guggulsterones - Stimulates thyroid and thereby may increase metabolism.

Gymnema - Historically used to treat diabetes. May inhibit taste for sweets.

Product Features

Stacker 2 claims to be "The World's Strongest Fat Burner". If fat burner is what you seek, GNC Burn 60 is exclusively used for weight loss and can be taken on the go. The formula, called a "Proprietary Blend", is designed to increase your metabolism and therefore your body heat. Be it a proprietary blend or not, many of these ingredients are common in fat burners like Instant Knockout. This stimulates your brain and raises your heart rate. White willow bark is essentially aspirin and the caffeine completes the stack. In addition to weight loss, benefits claimed are a decrease in appetite and an increase in energy.

Advantages of Stacker 2

  • Inexpensive.
  • Ephedrine free.
  • Contains ingredients proven to be helpful in weight loss.

Disadvantages of Stacker 2

  • Claims to be free of side effects while containing ingredients commonly known for its side effects, such as caffeine.
  • Does not break down the quantities for individual ingredients making it difficult to judge whether sufficient amounts are present to be effective.
  • Without ephedrine, there is no evidence that the product will work like a traditional "stack" or "ECA stack" product.
  • The importance of diet and exercised is not highlighted.
  • No before and after photos or testimonials.
  • No guarantee.


Stacker 2 has a few quality positive weight loss ingredients combined with ingredients that are not likely to do anything at all. It is assumed that the Proprietary Blend is greater than the sum of its parts. There is no evidence whatsoever to support that claim. When fad ingredients are involved, like in Batch 5, dieters often report ineffectiveness. It's impossible to measure the potency of the product or determine if there is enough of the ingredients to be effective. If you have had success with traditional "stack" products in the past, you will be disappointed with Stacker 2.

Summer Banks Dietspotlight Author
About the Author:

Summer Banks, Director of Content at Dietspotlight, has researched over 5000 weight-loss programs, pills, shakes and diet plans. Previously, she managed 15 supplement brands, worked with doctors specializing in weight loss and completed coursework in nutrition at Stanford University. full bio.

36 Stacker 2 Reviews

  • Imran

    Today is my first day on stacker, iv took 1 pill after breakfast and ran on treadmill for like 15 min, and I feel like iv got plenty of boost to go to work and make it happen!!! I’ll post back in few days for further updates…

  • Any hair side effects?

    Can it make hair thin

    • Stephen (Editor)

      Hi. Laurie. It is quite possible, since hair loss can be a common side effect with products that contain ephedrine. But, if you continue to have side effects, it’s best to consult with your physician. If you are worried about this, maybe you could sample Dietspotlight Burn instead (haven’t seen those side-effects with it).

  • Your Name

    These freaking stacker 2 pills is what killed my husband. Everytime I see them in a store I want to clear the counter!!!!! I love and miss my husband very much

  • paul

    Great energy boost for working out, but a but of jitters and a bit of stomach discomfort but not that bad. Hunger suppression is great. restless sleep though. on and off mild headache. will not burn fat alone but helps increase the intensity of my workouts and kill hunger. i pretty much use it as a pre-workout. i have dropped 40 pounds in 3 months.

  • Your Name

    I just need to know if it can make your skin itch? I started taking it about a month ago and then the itching started. It was my husband that figured out the itching started about the same time as when I started Stackers 2. I also take a thyroid pill but have for years. Could they conflict with one another?

    • Jessica (Editor)

      Hello. Consult with your physician before continuing this product to make sure its safe and effective for you to use. One you do, perhaps you can try Dietspotlight Burn for proven weight-loss results.

  • Michelle

    I took one pill at 6 am. I feel jittery and my heart is racing. It’s almost 2 pm now and my pulse is 130. I don’t like this pill.

    • Mimi

      I went to the emergency room almost unconscious and committing for hours. I am lucky to be alive

  • Nola

    I was size 20 and 240 pounds before I start on stacker 2 ,when I took stacker 2 I love it ,it boost my energy to go the whole day ,it help me not to want food all the time but most of all it drop me down to a size 14 and 195 pounds,I stop using it when me and my boyfriend tried for a baby and we did have one 2 months ago I gain up to 249 and back up to size 18 now I just start on stacker 2 today had to loose all that weight before work and …..yes ….it may not work for everyone but it definitely work for me !!

  •  Jessica (Verified User)

    Stackers 2s put me in the hospital last night.. I took 2 and it caused me to OD on caffeine .. I was diagnosed with accidental caffiene overdose.. I thought i was dying!!

  • carol king

    stacker 2 was horrible for me I have been sick to Stomach throwing up for 6 hours now extremely jittery chills not safe very scary feeling

    • Bella

      These folks with their back killing them, throwing up for days at a time, having to go to the ER for their legs being ‘jelly’…..I’m no doctor, but I would bet that it’s not the ‘stackers’ that are making your THAT ill. Find out what is really going on before you blame them. Seems to me, you didn’t wash your hands well after going out and you caught a stomach bug or the flu. Some major dramatics going on. It’s probably safe to say, those are the ones who are going to sue the company for millions when you probably just had too much dairy.


    I tried the 4 pack pills, could not tell I even had taken one at all… I want my 5 hour energy drinks back… NOW!!!
    These things DO NOT WORK!!!!

  •  It gives me tons of energy !
    raymond (Verified User)

    Tell us your thoughts about Stacker 2. i have been taking it for about 4 days. just one in the morning. yes it gives me tons of energy, but remindes me of speed. or what i think it would be like. but, its doing what i wanted which is keeping me from getting hungry. it cheeper than red bull, but will it be addictive well see. this product i know will not burn fat unless you use it with excercis. but im very lean as it is and walk a lot each day.

  • It made me lose craving not fat !!
    Ylolaour Name (Verified User)

    i started using rhis product two weeks ago it just made me lose the craving not the fat

  •  Stacker 2
    Your Nalol sme (Verified User)

    its great i just started taking the stacker 2 and it gave me energy and less cravings. I recommend to those who are trying to lose the late eating crash

  • Stacker 2
    Your Nadonnarachieleme (Verified User)

    Gave me a headache made me nauseated

  •  it did work for me
    Tina (Verified User)

    I took stacker 2 many years ago. I believe it was in the 80’s and it gave me an incredible amount of energy and it was like it melted the fat away without diet and exercise. I swear by stackers 2. I couldn’t believe how it melted the fat away without even cutting out any of the food I normally eat and I had lost 90 pounds but once you stop with any diet pill you gain back the weight you lost and then some. Don’t get me wrong it did work for me but to keep the weight off you must continue to take the diet pill no matter what one it is that you’re taking.

    • Your Name

      Ya but you don’t always wana depend on a pill to make u loose weight , once u stop taking the pill u could start exercising more often or even on a simple duet such as fruits and veggies and if u love meat just watch how much your eating plus breads or anything along that line can lead to weight gain….?

  • New formula did nor worked for me !
    David Baker (Verified User)

    I used the original stacker 2 when it had the ephedrine and it was awesome !! lost 80+ lbs but when they changed the formula it just did not work for me anymore. now years later I have regained the weight and am still searching for something that works !!

    • joanadaur

      Me too!!’m

  • Stacker 2
    Kimberly (Verified User)

    Stacker 2 may not burn fat alone but it definitely gives your workout a boost!

  •  They gave me energy !
    Veronica (Verified User)

    I took two stacker 2 pills and they gave me energy but I got jittery and nauseated and I couldn’t sleep that night. I tried them again next day but only took about a 1/3 of a pill and I got better results.

  •  Hope this works for me
    Your Name (Verified User)

    I just got some to day I’m gonna try them be cause I hear their its good energy boost. So hope it works for me

  •  Loved the product.
    mike (Verified User)

    stacker works great for energy made it through a long day at work which usually drags on and on heart rate does go up a little but not bad as for the weight loss part not sure just started taking them today i took 1 after breakfest and 1 after lunch and no problems it delivers a big boost in energy

  •  This works for me
    shawn williams (Verified User)

    stacker work for me i have energy all day long i try others diet pills but i didnt have energy….for me i have to stick with stackers.

    • Marisol

      I agree! I only take one pill in am and that’s it. It gives me energy to work out and no side effects!

  •  Good energy booster in small amounts
    keith (Verified User)

    I use stacker 2 everyday. I only take 1/3rd of a cap,you dont need to take a lot to make it work.Small amounts will give you a boost without making you feel sick, your weight loss will come from diet and exercise not from pills.

  •  Product is not good for my health
    donna davis (Verified User)

    i been takin stackers2 for 1 week i felt like my heart was gonna bust my back hurts my stomac hurts my leggs feels like there jelly im so exculsted all i wanta do is sleep im soo sick i wanna die that i cant stand the pain im going to the er tommorow and get help i may end up sueing for this pain n suffring i have kids that i need to focuse on i trusted this diet pill all it did was put me in pain ill never take3 this trash agean thanks for this sevier pain i hope they take this junk off marketmarche

    • isaac

      Not for you you may have allergic reaction works great for me

      • Jerrod Walker

        You took 3 stacker 2 capsules at once? Jw cause the only way I get a boost is by taking 1 every couple of hrs

    • Your Name

      Tou should not take three at once and you can but not sue,you should know he risk and need to realize being smart and not overdosing is wise!

    • Your Name

      I’m sorry, but i guarantee you……you being that sick had nothing to do with Stackers.

  •  Product caused sickness
    joseph hyde (Verified User)

    well stacker made me feel really bad and i got sick and my heart had pain in it so i dont know whats going on but i dont like it im not buy stacker no more bye

  •  i was going to die
    cindy shippy (Verified User)

    i thought i was going to die after taking stacker 3. they shouldnt be sold. my whole boby inside and out shook .