Updated: 04/18/2017 - Site operated by Leptigen
By Summer Banks Mar 31, 2017

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, Leptigen.

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]

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.

Also: read our Leptigen Weight-Loss Kit review »

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 Leptigen. 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 Special Trial Offer, which is a good sign.

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.

Stacker 2 Questions & Answers:

We summarized hundreds of user comments about Stacker 2 into this helpful FAQ.

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[1], caffeine, green tea leaves, guggulsterone, cassia mimosoides extract and white willow bark.

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.

Can I take Stacker 2 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 Stacker 2.

What do users like about Stacker 2?

Some users like that Stacker 2 is a small capsule, making it easy to take and the affordability of the supplement.

What do users NOT like about Stacker 2?

We found that some users didn’t like the side effects from Stacker 2 and that the product didn’t help dieters lose weight.

How do I contact the Stacker 2 customer service department?

You can contact the Stacker 2 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.

Can I contact Stacker 2 through social media?

Yes, you can contact Stacker 2 through Facebook and Twitter.

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?

According to the information on the official website, each serving of Stacker 2 contains 200mg of caffeine. [2]

Does Stacker 2 come with a guarantee?

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

Do you know of any special deals or discounts on Stacker 2?

There are special deals and discounts on Stacker 2. You will receive free shipping on all orders of $50 or more. However, the last seveal months have flown by, considering our readers have been taking advantage of Leptigen’s Special Trial Offer. Click above to learn more.

Stacker 2 User Tips:

7 Top User Tips

Over the years, we’ve noticed that Stacker2 users have something to say. After going over thousands of comments and reviews we chose these tips to help you learn even more about this product.


“I don’t take Stacker2 as it says to on the bottle, but do take on at a time, at three schedule times during the day in place of caffeine.” Maria


“Take no more than two a day or you will be up all night.” Jan


“You have to do this for a while before it really starts to work. Don’t give up.” Perry


“I only take 1 a day, that’s all you really need. It helps you burn fat IF you exercise. That’s the main key to this working.” Chuck


“I have to drink a lot of water with this or I get really bad headaches. As long as I stay really hydrated it’s not so bad.” Tina


“This definitely isn’t a magic weight loss solution. You have to be willing to change your diet and exercise if you want it to work.” Joe


“You can’t expect it to work overnight. You didn’t pack on the pounds in a week and you won’t lose them that fast either. ” Mark

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]

Stacker 2 Side Effects:

Nowadays, there are a lot of weight-loss supplements around every turn. With that said, it’s important to realize that taking a natural solution doesn’t necessarily mean it can’t cause a negative side effect. With every mixture, there’s a possibility for an adverse reaction, although Stacker2 side effects are fairly uncommon, it doesn’t mean they don’t happen to some users.


A headache is described as a pain in any area of the head or neck. They can be categorized as cluster, tension, and migraines, which are all primary headaches.

What causes a headache?

Primary headaches are caused by over activity in pain-sensitive areas of the head. External pressure and temperature can cause a headache, as well as any direct physical stimuli. Stress, anxiety, and caffeine intake can stimulate nerves in the head as well.


Nausea is an uncomfortable sensation of queasiness or sickness in the stomach, typically preceding vomiting. You may experience a bitter or sour taste in the mouth and throat. These usually accompany nausea.

What causes nausea?

Nausea isn’t a condition in itself, rather a symptom of another issue. There are several factors, including food poisoning or food allergies, which could contribute to this symptom. Parasites or bacteria in uncooked food could lead to an illness which would trigger a nauseous feeling. [1]


Fatigue is the feeling of being worn out or unrelenting exhaustion. This condition doesn’t seem to be remedied by sleep or rest, often times having a direct impact on daily routines due to lack of concentration and weariness. [2]

What causes fatigue?

Fatigue could be caused by lack of sleep, jet lag, stress, or diet. More serious conditions could be sleep apnea (frequent stopping and starting of breathing), concussion, or a major depression disorder.

Leg Cramps

Leg cramps (charley horse) are the involuntary contraction of one or more muscles in the leg. This symptom is fairly common, but could have negative effects on sleep and daily routine.

What causes leg cramps?

Holding a certain position for a prolonged amount of time could cause this effect, as well as dehydration. The narrowing of arteries to the leg could cut blood flow and increase chances of muscle cramps during strenuous activities such as exercise or sports.

Stacker2 side effects are few and far between, but there have been some reports of leg cramps, fatigue, nausea, and some others. In order to save yourself the potential negative reaction, it’s always a good idea to seek the advice of a doctor before taking any supplement, especially if you are under the age of 18, are taking prescription medications, have a pre-existing medical condition, or are pregnant or nursing.



Stacker 2 is a supplement that contains ingredients such as green tea, caffeine, and white willow bark to help boost metabolism and boost weight-loss. We know that they are uncommon, but we went out and found comments from users who experienced side effects.


“The third day I was waking up with mild headaches.”    Bailey


“Gave me a headache and sometimes nausea.”    Gregory


“I noticed it also made me jittery and sometimes gave me a headache.”    Thurston


“When I bought this product I was expecting to get a boost of energy instead I got headaches.”    Fredrick


“Makes me jittery, and actually got sick to my stomach.”    Dave


“I started getting weird pains in what seemed like my liver.”    Bryan


“I just started taking this product last week and now I’m having problems with cramps in my legs, my whole body is jittering, and I can’t sleep.”    Adam


“This product made me really sick!”    Lucy


“Made me feel like my heart would explode.”    Rachael


“I go to sleep and get around 7 hours of sleep (just right for me). I was barely able to wake up the last 2 or 3 mornings without feeling like I had no sleep at all.”    Stephanie


We’re keeping a close eye on one that’s not associated with harmful side effects, that’s backed by positive customer reviews. To learn more about Leptigen, click above.

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 Blend 267mg *
- Yerba Mate * *
- Green Tea Leaves * *
- Guggulsterone * *
- Cassia Mimosoides Extract * *
- White Willow Bark * *
Caffeine 200mg *

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 Leptigen. It contains clinically-tested ingredients and have been shown to work. Want to learn more about it; click above.

Get Your Sample Today »
Dietspotlight Author
About the Author:

Summer Banks, a content strategist at Leptigen, has researched over 5000 products in the past 10 years. She has years of nursing training, experience as a manager responsible for 15 supplement brands, and completed coursework on Food and Nutrition from Stanford University. full bio.

Rating: 3.3. From 71 votes.
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User Comments

35 Comments on "Stacker 2 Review"


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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


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?

Hello. All users are different and can experience different results; please make sure to consult with your physician before continuing this product to make sure its safe and effective for you to use.


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.


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


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 !!

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


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!!!!


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.

Ylolaour Name

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

Your Nalol sme

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

Your Nadonnarachieleme

Gave me a headache made me nauseated


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….?

David Baker

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 !!


Me too!!’m


Today is my first day on stacker, iv took 1 pill after bereakfast 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 furtthur updates…?


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


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.


Can it make hair thin

Stephen (Editor)

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

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


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

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!