Updated: 01/09/2018

GNC X12 Review - 5 Things You Need to Know


A diet product’s worth depends on whether it actually helps people lose weight. Let’s find out if GNC X12 really works. We took the time to create a comprehensive review, focusing closely on the ingredients, side effects, customer-service quality and scientific studies. We additionally scrutinized various user comments from all over the internet. At last, we compressed all of the data we collected to give you the facts.

GNC X12 Readers: Click here to find out why we're giving away samples of our product, Burn HD.

What is GNC X12?

To begin with, GNC X12 was a popular weight-loss supplement that supposedly worked by increasing an individual’s metabolism. The ingredients included caffeine, black pepper extract, and capsicum fruit extract. It is specifically aimed at pushing calorie burn to 12 times the normal rate.

GNC X12 was made by GNC Holdings Inc. located in Pennsylvania. The company was established in 1935 and is well known for dietary and weight-loss supplements, but read on…

Products Similar to GNC X12

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Burn HD (Sample offer)read

Availability– “No Longer at Stores”

The first issue we have is that the company no longer sells GNC X12 through their official retail outlets. While it may still be possible to obtain a bottle of the supplements through secondary sources, it is concerning when a business stops supporting one of their products. According to our Research Editor, “If they don’t have enough faith to continue producing it and supporting it, that is a good indicator that consumers should skip it.

According to one consumer, “I had a bottle from ages ago and I wanted to try it again but I couldn’t find it.”

Another claimed, “I called their customer service department to try to find out where I could get a bottle but the rep I talked to didn’t even know what it was.”

Others didn’t have an issue and said, “It use to work great for me and I’d be willing to buy it from a third party.”

One reviewer stated, “I had an extra bottle from the last time I needed to lose weight so I just used it.”

Another claimed, “I went into the store and they said they were selling something similar so I went with it instead.”

Side Effects– “This Was a Problem.”

There’s some evidence that GNC X12 side effects are an issue that could have contributed to the supplement’s failure.

One unhappy dieter said, “I was so anxious when I took this I had to stop.”

Another experienced worrisome symptoms and said, “My blood pressure went way up so I had to stop.”

Other dieters had minimal problems. According to one, “It’s been awhile but I don’t remember anything more bothersome than a headache.”

Some had no memory of any side effects like this reviewer, “It always worked great for me with no problems at all!”

Another said, “Weight-loss supplements all seem to have side effects but as long as it makes me lose the weight I don’t care.”

According to our research, availability and side effects are major factors in choosing a weight-loss supplement. If the GNC X12 causes significant negative reactions and isn’t readily available, people will look elsewhere.

The Science – “No Proof”

At DietSpotlight, we need to see the proof behind the claims. At this point, GNC X12 isn’t even supported by the manufacturer and the company does not make any proof of efficacy available for review.

The Bottom Line – Does GNC X12 Work?

Should I race out for the last bottle of GNC X12? Even if you are able to find the product, we weren’t able to find enough supporting evidence that it would work as intended which is why we are hesitant to give it our endorsement.

If you are ready to drop those extra pounds why not try a product with ingredients that have been backed by scientific research. The company that makes the supplement should be willing to stand behind it and offer high quality customer service to their clients.

Among the best weight-loss products we’ve seen this year is one called Dietspotlight Burn. It contains four key ingredients, which have been shown in documented clinical testing to help boost fat loss and kick-start metabolism. We didn’t pinpoint any negative user reviews online, and the overall customer response indicated people were seeing positive results. It’s also readily available and supported by the company behind it.

The manufacturer of Dietspotlight Burn is so sure of their product they’re offering a Special Trial Offer, for those who want to give it a try.

Learn More About Burn HD »
GNC X12 Review
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What are the side effects of GNC X12?

GNC X12 side effects, reported by some customers, include jitteriness, anxiety, nervousness, headache and sleeplessness.

What are the ingredients in GNC X12?

GNC X12 ingredients include caffeine, capsicum and Bioperine.

How do I know if GNC X12 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 GNC X12 work?

There are no studies showing GNC X12 will help you lose weight, although there’s research showing the effectiveness of caffeine and Bioperine. Unfortunately, the findings don’t point toward this supplement.

How much does GNC X12 cost?

GNC X12 costs $45.99 for 45 capsules.

How should I take GNC X12?

You should take three GNC X12 capsules per day. One bottle lasts 15 days.

Will I need to diet and exercise while taking GNC X12?

No, you don’t need to diet or exercise while taking GNC X12, but the company recommends eating healthy and adding fitness to better results.

Does GNC X12 come with a guarantee?

GNC X12 doesn’t come with a guarantee.

You may want to think about what you long-term weight-loss goals are, think about what GNC X12 offers and then consider a supplement like Dietspotlight Burn, which contains some clinically-tested ingredients and has been shown to work.


Previous GNC X12 Review (Updated August 29, 2014):

What You Should Know

GNC is a supplement company with a long reputation for quality products. The GNC X12 product is designed as a metabolism booster with a thermogenic blend that will help dieters burn calories more efficiently. While thermogenics are a benefit in a weight loss supplement, we will look at the GNC X12 formula more closely to see if it can deliver on its promises. This product claims to help you burn twelve times more calories than you would burn without a supplement. GNC also promises that their X12 formula will support improved endurance and performance. Unfortunately, the company does not appear to provide any scientific evidence or clinical research to support these claims. The lack of information makes us wonder if this formula really is as good as it says or if the company is luring consumers into purchasing their product based on unsupported claims. We are pleased to find that GNC provides a complete ingredient list for products so customers can decide for themselves if the formula is really as potent as it says.


The GNC website includes a complete listing of product ingredients, which includes Caffeine, Black Pepper Extract, Capsicum Fruit Extract Bioperine, Cellulose, Titanium Dioxide (Natural Mineral Whitener), Gelatin, Artificial Colors (Blue 1, Red 40). The company states that there are no artificial flavors, starch, sodium, wheat, gluten, corn, soy dairy or yeast in the formula. This means that the supplement is appropriate for many consumers, even those with dietary restrictions. Caffeine is a standard ingredient in thermogenic formulas because it can boost the metabolism and increase energy. However, there are safe and unsafe levels of this substance and too much of a good thing can result in nervousness, jitters, irritability and insomnia. Black pepper extract and capsicum may have some thermogenic properties, but we believe there are more effective products available for this purpose.

Product Features

We are disappointed in the fact that GNC does not appear to offer any sort of money back guarantee on their products. We believe that this policy shows confidence in the product by the manufacturer and offers consumers the chance to try new formulas risk free. The product sells in GNC stores and on the company website for about $25 at the time of this review. This is a significant savings over the original price of almost $50 per bottle.


  • GNC X14 is a thermogenic that can boost the metabolism and burn calories.
  • The product is currently offered at a discounted price on the company website.


  • The thermogenic ingredients may not be the most effective.
  • There isn't anything in the formula to act as an appetite suppressant.
  • The company does not appear to offer a money back guarantee.


While we like the ideas of thermogenics in a weight loss supplement, we are not convinced that the substances in GNC X14 are the most potent ones available. We would urge consumers to look for top quality products and ingredients to get the biggest bang from their weight loss buck.
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.

23 GNC X12 Reviews

  • I wanna know how long would it take for me to lose 20 pounds using this product?

    I wanna know how long would it take for me to lose 20 pounds using this product?

    • Maribel (Editor)

      Hello Diane. All users are different and can experience different weight-loss results.

  • Where could i purchase the x12 fatburns product?
    Trent Forney

    Were could i purchase the x12 fatburns product separately store or website on hand

    • Maribel (Editor)

      Hi Trent! For more information on where to purchase this product, please refer to the GNX X12 official website.

  • Where can i find x12?
    shalisa walker

    Were can i find x12 at

  • do the x12 wrok i need to loss about 55 pounds
    tywonna griffin

    do the x12 wrok i need to loss about 55 pounds

    • Maribel (Editor)

      Hello Tywonna. All users are different and can experience different weight-loss results.

  • How long does X12 stay in your system once administered?
    Ttacy Ross

    How long does X12 stay in your system once administered?

    • Maribel (Editor)

      Hi Ttacy! Please make sure to consult with your physician for more information.

  • Stephanie h

    So, my first time raking x 12..but not my first time taking a thermogenic. Horrible. So about 25 min into my workout I thought I had to throw up. So I walked outside and then proceeded to sit on the ground because the cramps that camp a few minutes after we’re unbearable. I literally though I was dying. It took about 10 min for the pain to go away. Following hours later came headaches and I couldn’t get cool. I took this pill with a doughnut, of course not a full meal. So apparently if you take with a meal this wouldn’t have happend. Anyways, I’m going to try it again but with food. If this happens agains, I will more than likely return.

  • caffeine is actually in x12
    Amanda (Verified User)

    My boyfriend had me try it out. I misread the directions, and I ended up taking two pills instead of one. It made me really jittery and it made me get sick twice and it felt like my heart was going to beat out of my chest….Does anybody know exactly how much caffeine is actually in x12?

  • I think its going to be great
    Lynzer (Verified User)

    just started taking this and I think its going to be great it gives me extra energy to push through my 3 miles quicker and I am just going to take it on the days I work out so I don’t get too dependent on it, I am not trying to lose weight, just a little baby fat.

  • Diet pill

    im taking lipofuze now but it doesn t seem 2 work … can i take x12 while on other diet pill?

  •  Hydoxycut
    Crystal (Verified User)

    My sister and I took it at the same time. I didn’t have any adverse effects aside from mild stomache cramps…probably from all the pepper.She did get really flushed(red,itchy) but was fine after an hour,she did a little bit the next time,but hasn’t had a problem with it since. It’s actually really common and nothing to worry about,you shouldn’t have a problem after 2 or 3 times. There’s nothing unusual in there,it’s not too strong. It’s not like hydoxycut or xenadrine which zaps your appetite and makes you jittery. It’s more like an aid to your workout. You HAVE to workout to lose weight on this product but it does work if YOU work too. For example,if you run a mile,it’s like you ran 2 or 3. And the good thing about it is when you stop taking it,you won’t gain the weight back like on a strong diet pill.

    KYLE (Verified User)


    • tommy

      most of them are not. it really is flushing from the niacin. for most of them

  •  I am LOVING this product!
    Sandy (Verified User)

    I am LOVING this product! It totally helped me blow through my plateau, and I lost 7 pounds in the first week!

    Do not take it on an empty stomach. If you are taking it before breakfast on the non-exercise day, then you definitely need to eat something right after. It gives stomach pains, nausea, etc if you do take it on an empty stomach. Obviously really easy to avoid….just take it with food and water!!

    Reviewers state that this is a mild product, and make it seem like that’s a bad thing, but to me that’s a perk! If you can’t handle a lot of caffeine, then this is a good fat burner for you.

    When exercising, the sweat just drips off and you can totally tell it’s working. Yep, two thumbs up for this one!

    PS. Check the ingredients. Google each one. If you’re allergic to any of them, do not take the product. With any product or food, don’t consume it if you might possibly have an allergic reaction to it.

    • SCalvin

      I agree I have only been taking it for 2 days and so far I am down 4.5lbs… This pill with exercise is good! And you really don’t have the jitters or shakes. I like it!

      • Evelyn

        Are you guys taking only one pill? the box recommends one but the lady at GNC told me to start with one the up to two.

  • I had the same allergic reaction
    Kevin smith (Verified User)

    I had the same allergic reaction, minus the throat swelling. I got red in the face first, than blotches on neck back chest and shoulders. It felt like I had a fever. I immediately to Benadryl, which helped within an hour.

  •  Hated the product
    beachblonde2986 (Verified User)

    Horrible!!! I took X12 one time and it made me have a severe allergic reaction to it. It made my whole body feel like it was on fire and it made me red and itchy all over, then it closed up my airway (very scary) and it gave me extremely painful cramps in my stomach. I was laying on the floor in the fetal position crying for about an hour before the cramps subsided a little. It made me throw up as well, but even after that, I still felt the after math of it. Please stay away from this product. I have read many other reviews on this and almost everyone has had the same experience as me. Dont so it!

    • george

      It’s a side effect called flushing, not an allergic reaction. google it

  •  Result coming very slow.
    hardik (Verified User)

    i tok X12 but it hardly shows ant difference its very light but its very safe