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.
What is Stacker 2?
First off, Stacker 2 is a fat burner using the principles of the infamous ECA Stack.  The ingredients are yerba mate, green tea, guggulsterone, cassia mimosoides, white willow bark  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. 
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.” 
“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.
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. 
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 ,” 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 , green tea extract and kola nut  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.”
Also: read our Burn HD Weight-Loss Kit review »
“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.”
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 »