Updated: 02/02/2016 - Sponsored by Leptigen

Stacker 2 Review - Does This Dietary Supplement Work? Are side effects and questionable results deal breakers?

Editor's Review: 3.5 / 5.0

stacker-2-product-imageDiet 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. We finished off our study by reading hundreds of reviews. We summarized and condensed to give you the bottom line.

EDITOR'S TIP: Substitute Stacker 2 with a proven fat burner such as Leptigen for better results.

What You Need to Know

First off, the name “Stacker 2” is inspired by a common supplement composition called an “ECA Stack,” which is made with ephedrine, caffeine and aspirin. Fortunately, it no longer uses ephedrine, but the name remains. The complete list of ingredients is kola nut, yerba mate, cassia mimosoides, white willow bark, caffeine anhydrous, green tea, guggulsterones and gymnema.

According to Stacker 2’s website, it was engineered 20 years ago by NVE Pharmaceuticals to give weightlifters an herbal alternative to many fat burners at the time. It’s available in health stores and on its official website. We like the fact that Stacker 2 ditched ephedrine as an ingredient and the focus on herbals is a plus, but read on…

Side-Effects – “Look Out?”

The first concern we had with Stacker 2 is the potential for side effects. “If you regularly take Stacker 2 pills, you may experience some significant adverse reactions,” said our Research Editor.  “Especially for people who are sensitive to caffeine.” If you take Stacker 2 alongside your regular servings of coffee or other caffeine sources, you might have a problem.

“Gave me a boost of energy but 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. They are not fun at all,” offered another.

Scroll below for one of the best products we’ve seen over the last year.

Questionable Results – “Another Concern”

According to many reviews online, the fat-burning qualities alluded to in the description were not often realized. “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 another.

Upon reading further reviews, we realized that the issue of fat burning was a common one: “I tried them again but they didn’t really do much for me, nor did they help me lose any weight,” explained one person.

Our research has shown if there is some particular part of a diet program that is especially troublesome (a negative side effect like excess energy or the jitters, a  lack of fat-burning success, etc.), then the likelihood of long-term success is slim. If Stacker 2 does in fact cause adverse reactions and fail to help your body burn more fat, you should look elsewhere.

The Science – “Legitimate?”

Some of the ingredients in Stacker 2 have been clinically verified to work and some simply have not. The white willow bark extract, green tea extract and kola nut are common ones that have been proven to be mildly effective. However, the rest lack the same study and may or may not work at all. Furthermore, we have no way of knowing if the “stack” principal even works without ephedrine present in the formula. We at DietSpotlight find clinical reseaerch to be hugely important and we would like to see some for Stacker 2 before we consider recommending it.

The Bottom Line – Does Stacker 2 Work?

Ladies and gentlemen, what’s the take on this one? Stacker 2 looked like a decent fat burner at first. We were surprised to find out, however, that many people didn’t experience any fat loss when they used the product and some of the side effects looked downright unpleasant. It also concerns us that the effective ingredients can be purchased for less than $10.

If you are still in the market for an effective fat burner, you need a supplement that is clinically proven to work. A product that doesn’t have nasty side effects. You also need one that is worth your money.

Among the best products we’ve seen in 2016 is one called Leptigen. It’s a blend of four fantastic ingredients proven to help boost metabolism and burn fat. Thankfully, it has been tested in scientific studies and verified by clinical research. Upon reading user reviews online, we haven’t found any side effects, but we did find plenty of reports of dieters seeing fantastic results.

The makers of Leptigen are even offering a Special Trial Offer – always a good sign, in our opinion.

Learn More About Leptigen »
GD Star Rating

How Does Stacker 2 Compare?

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

What You Should Know

Click Here To See Our Highest Rated Review

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.

List of 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". 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.

See Our Featured


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


  • 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.

Stacker 2 FAQ:

We summarized hundreds of user comments about Stacker2 into this helpful FAQ.

What are the side effects of Stacker2?

Some side effects of Stacker2 include anxiety, nervousness, jitteriness, increased heartrate, irritability, sleeplessness, upset stomach, headaches and shortness of breath.

What are the ingredients in Stacker2?

The ingredients in Stacker2 are yerba mate, caffeine, green tea leaves, guggulsterone, cassia mimosoides extract, white willow bark, gelatin, stearic acid, magnesium stearate, titanium dioxide, dibasic calcium phosphate, microcrystalline cellulose, fd&c yellow #5, fd&c blue #1, fd&c red #3 and fd&c yellow #6.

Does Stacker2 work?

There’s no scientific research backing the effectiveness of Stacker2. We found studies linking green tea and caffeine to weight-loss, but nothing specific to this formula. You may want to take a long look at Stacker2 and replace it with a supplement like Leptigen, which contains ingredients clinically proven to work.

How much does Stacker2 cost?

Stacker2 costs $19.99 on the official website.

How should I take Stacker2?

You should take one Stacker2 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.

Can I take Stacker2 if I have a health condition?

Women who are pregnant or nursing, those with health conditions, anyone taking prescription medications of any kind or under 18 years of age should consult with a healthcare professional prior to using weight-loss supplements, including Stacker2.

What do users like about Stacker2?

Some users like that Stacker2 is a small capsule, making it easy to take and the affordability of the supplement.

What do users NOT like about Stacker2?

We found that some users didn’t like the side effects from Stacker2 and that the product didn’t help dieters lose weight.

How do I contact the Stacker2 customer service department?

You can contact the Stacker2 customer service department by emailing support@stacker2.com, mailing correspondence to NVE Pharmaceuticals 15 Whitehall Rd. Andover, NJ 07821 or by calling a representative at 1-973-786-7868.

If I take more Stacker2, will I improve results?

No, you will not improve results if you take more Stacker2.

How much caffeine is in Stacker2?

Each serving of Stacker2, one capsule, contains 200mg of caffeine.

Does Stacker2 come with a guarantee?

There’s no mention of a guarantee with Stacker2.

Do you know of any special deals or discounts on Stacker2?

There are special deals and discounts on Stacker2. You will receive free shipping on all orders of $50 or more. However, the last several months have been a whirlwind with our readers taking advantage of Leptigen’s Special Trial Offer, which is simply the cost of shipping and handling. Click here to give it a try.

12 User Reviews About Stacker 2

Leave comments below
  • 1

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


  • 2

    Can it make hair thin


    Stephen (Editor)

    Hi. Laurie. It is quite possible, though to be sure please consult with your doctor.


  • 3
    Your Name

    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


  • 4

    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


  • 5
    shawn williams

    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.



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


  • 6

    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.


  • 7
    donna davis

    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



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


  • 8
    joseph hyde

    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


  • 9
    cindy shippy

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


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