GNC X Review

Editor's Review: 2.8 / 5.0

What You Should Know

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X-12 is GNC’s house brand fat burner. GNC is one of the largest health supplement companies in the country with stores everywhere. GNC claims that X-12 burns calories 12 times as fast after a workout and will burn 278 more calories along with exercise. We appreciate when a company uses specific measures and numbers in its claims but we were ultimately disappointed that GNC did not provide any support for the X-12 claims on its website. This prevents consumers from assessing the effectiveness of the product.

GNC X-12 is said to contain ingredients that increase the body’s thermogenic response. Thermogenesis is the increase in metabolism in the body’s adipose (fat) tissues and can be induced by thermogenics like caffeine, aspirin, ginger, capsicum and ephedra. These are common ingredients found in many diet aids, with the exception of ephedra, which has been banned in many countries for its dangerous side effects.

GNC X-12 can be purchased directly from the manufacturer’s website. The website description of X-12 is brief and does not provide any links to clinical research supporting the product’s claims, although it is said to be “clinically researched”. The regular price of GNC’s X-12 is around $50 for a one and a half month supply. This makes the product competitively priced.

List of Ingredients

According to the GNC website, the ingredients in X-12 are: niacin, caffeine, Capsimax capsicum fruit extract (red pepper), and black pepper extract. The non-active ingredients in X-12 are: cellulose, titanium dioxide, gelatin, and artificial colors.

Product Features

The ingredients in GNC’s X-12 are commonly found in diet aids that rely on a thermogenic response. It is unfortunate that GNC does not provide details of clinical research on this product or customer testimonials. Both would allow us a better understanding of the potential of X-12. There is nothing in the X-12 formulation that grabs our attention and we find that this is likely just an average product. This is common with companies that manufacture many products. They do not have the focus or time to ensure that each product is as effective as it can be.

So while the ingredients in GNC X-12 will definitely trigger a thermogenic response, we feel that there are other products on the market that are far more effective and produce more dramatic and long-lasting results. Those with allergies to red dyes should consult with their doctor before using this product.

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  • Consumers can purchase this product directly from the manufacturer’s website.
  • X-12 contains ingredients known to trigger a thermogenic response.
  • The product is competitively priced.


  • No clinical research is available for X-12 at this time.
  • No product samples are offered from GNC for X-12.
  • X-12 may not contain proven ingredients for long-term weight management.
  • X-12 contains known allergens.


While GNC is a well-established and trusted source of health supplements, that does not mean that every one of its products are stellar and we believe that to be the case with GNC X-12. While the ingredients are on the right track, we feel that there are better and more proven formulations on the market that are more likely to provide long-lasting and dramatic weight loss results.

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