GNC GenetixHD Iso-Define Reviews

gnc genetixhd iso-define

GNC claims GenetixHD Iso-Define sets the standard for those in pursuit of physical perfection.

The company claims to have a revolutionary ultra pure whey isolate hyper defining matrix that builds muscle fast.

Is GNC Genetix Iso-Define really the best option for those wanting that perfect body? To find out, I researched the formula.

The Ingredients

Below is a list of the important ingredients contained in GNC GenetixHD Iso-Define. They were chosen to burn fat, build muscle, and enhance recovery.

Whey Protein Isolate

Whey protein isolate is a highly filtered cheese by-product that affects muscle mass when combined with exercise. However, whey protein isolate effects are varied, and experts agree more research needs to be conducted.

For example, one study tested whey protein effects with and without resistance exercise. Results show those taking whey protein without exercise saw no change in muscle mass or strength. On the other hand, those taking whey protein with resistance exercise experienced small change in muscle strength but no change in muscle mass. [1]

Another study conducted on elderly males suggests whey protein consumption builds and preserves skeletal muscle. [2]

Researchers also found young resistance trained men taking 10 g protein with carbs saw a significant increase in their muscle protein synthesis. [3]


CLA stands for conjugated linoleic acid, which is purported to induce weight loss.

However, researchers supplemented 26 rats with CLA. They concluded CLA doesn’t lower weight; in fact, they found it impairs insulin function. [4]

Furthermore, experts at WebMD say CLA supplements may decrease body fat but probably won’t lower BMI. [5]


MCTs are fatty acids that enter the mitochondria directly, instead of being broken down like other fats. This increases energy expenditure and weight loss potential with exercise.

A randomized, crossover, controlled-feeding trial on 19 overweight men shows a diet full of MCTs decreased body weight and promotes lean muscle gain. Specifically men with a lower initial body weight displayed best results in energy expenditure and fat oxidation after day 28 of the trial. [6]


L-carnitine is an amino acid that builds muscle.

Researchers conducted an experiment where they gave patients 2 g carnitine a day. The result was growth in muscle potential through an increase in oxidative metabolism. Researchers concluded carnitine has significant effect on muscle building. [7]

However, GNC GenetixHD Iso-Define only contains 500 mg carnitine, so the results won’t be the same as those found in the study.


L-leucine is an amino acid that builds muscle and enhances recovery.

In animal studies, oral leucine supplementation enhanced muscle recovery and muscle mass after intense exercise. [8]

Human studies show leucine supplementation builds muscle mass short term, but when taken long term, usually 3 months or longer, it loses its effect. [9] [9]

Lutemax 2020 Lutein

Lutemax 2020 Lutein is a combination of lutein and zeaxanthin; both ingredients are taken for various eye problems. [10]

Further research is needed to determine potential effects on exercise enhancement.


GNC GenitixHD Iso-Define comes in 2 flavors: Berry Sorbet and Swiss Chocolate.

Both are sold for the same price, but Berry Sorbet only contains 1.5 lbs. powder and Swiss chocolate contains 1.6 lbs. powder.

What Are the Risks?

There are side effects associated with the ingredients in GNC GenetixHD Iso-Define:

• Upset stomach
• Nausea
• Diarrhea
• Fatigue
• Thirst
• Bloating
• Cramps
• Reduced appetite
• Gas
• Vomiting
• Fishy odor in urine, breath, and sweat [11] [12] [13]

Warnings: CLA supplements may worsen insulin resistance in people with diabetes. CLA is also not recommended for pregnant or nursing women. Keep out of reach of children. [4]


GenetixHD Iso-Define is sold exclusively at GNC for $43.99, and the tub has less than 2 lbs. powder.

There are many other whey protein isolate products out there that are much more affordable.

For example, Now Foods Whey Protein Isolate 100% Pure Natural 1.2 lbs. can be purchased for $20.99 on The average customer rating for this product is 5 out of 5. Now Foods has been in business for over 40 years and seems like a fairly reliable manufacturer.

Another example would be Jay Robb Whey Protein Isolate Powder 1.5 lbs., also on for $36.75. This receives an average customer rating of 4 out of 5. Jay Robb is a clinical nutritionist with 3 decades of experience in health and welfare.

However, while these products are cheaper, they don’t include all the other ingredients GNC GenetixHD Iso-Define contains. The extra ingredients may be worth the bigger price tag.

The Money-Back Guarantee

GNC offers a competitive guarantee on all their products.

GNC gives customers 30 days to refund used or unused products if they aren’t satisfied.

To return:

• Refer to packing slip for specific return information
• Pack product back into original box
• Enclose bottom portion of the original packing list with the items, keep the top portion
• Product must be returned in good condition, used or unused
• Customer is responsible for shipping charges unless product is being returned as a result of manufacturer error
• Return to GNC 15A Avenue A, Leetsdale, PA 15056-1304
• Keep return tracking number
• Refunds will be given within 30 day of receiving returned product

Customer Reviews

According to customers, these are the pros and cons to GNC GenetixHD Iso-Define:


• Builds muscle
• Good value
• No artificial sweeteners
• Quickens recovery time
• Great taste


• Needs more flavors
• Pricy

Does Iso-Define Set the Standard?

The research behind GNC GenetixHD Iso-Define ingredients, though promising, is weak and makes me skeptical about the effectiveness.

Consequently, I rely heavily on customer reviews to determine its potency, and GNC GenetixHD Iso-Define has positive customer feedback.

Additionally, the money-back guarantee tells me GNC is confident in its product, though the price is a little high.

Because Iso-Define comes with such a great guarantee, I would say it’s worth a try. After all, you can always get your money back!

Leave a Comment


[1] Agin, Denise, Dympna Gallagher, Jack Wang, Steven B. Heymsfield, and Richard N. Pierson. "Effects of whey protein and resistance exercise on body cell mass, muscle strength, and quality of life in women with HIV." AIDS the Official Journal of the International AIDS Society 15.18 (2001). Web. 13 June 2013.

[2] Hayes, Alan, and Cribb J. Paul. "Effect of whey protein isolate on strength, body composition and muscle hypertrophy during resistance training." Clinical Nutrition and Metabolic Care 11.1 (2008). Web. 5 June 2013.,_body.9.aspx.

[3] Tang, Jason E., Joshua J. Manolakos, Greg W. Kujbida, Paul J. Lysecki, and Daniel R. Moore. "Minimal whey protein with carbohydrate stimulates muscle protein synthesis following resistance exercise in trained young men." Applied Physiology, Nutrition, and Metabolism . Web. 17 June 2013.

[4] "Conjugated Linoleic Acid (CLA)." WebMD, n.d. Web. 13 June 2013.

[5] Miranda, , Fernández-Quintela, Macarulla, Churruca, and García. "A comparison between CLNA and CLA effects on body fat, serum parameters and liver composition." Journal of Physiology and Biochemistry (2009). Web. 13 June 2013.

[6] St-Onge MP, , and Jones PJ. "Greater rise in fat oxidation with medium-chain triglyceride consumption relative to long-chain triglyceride is associated with lower initial body weight and greater loss of subcutaneous adipose tissu." Int J Obes Relat Metab Disord (2003). Web. 13 June 2013.

[7] Spagnoli, , Palmieri, Mauriello, Vacha, and D’Iddio. "Morphometric Evidence of the Trophic Effect of L-Carnitine on Human Skeletal Muscle." Nephron Journals 55.1 (1990). Web. 13 June 2013.

[8] Anthony, Joshua C., Tracy G. Anthony, and Donald K. Layman. "Leucine Supplementation Enhances Skeletal Muscle Recovery in Rats Following Exercise." The Journal of Nutrition (1999). Web. 13 June 2013.

[9] Rieu, Isabelle, Michèle Balage, Claire Sornet, Christophe Giraudet, and Estelle Pujos. "Leucine supplementation improves muscle protein synthesis in elderly men independently of hyperaminoacidaemia." The Journal of Physiology (2006). Web. 13 June 2013.

[10] Verhoeven, Suzanne, Kristof Vanschoonbeek, Lex B Verdijk, René Koopman, and Will KWH Wodzig. "Long-term leucine supplementation does not increase muscle mass or strength in healthy elderly men." The American Journal of Clinical Nutrition . Web. 13 June 2013.

[11] "LUTEIN." WebMD, n.d. Web. 13 June 2013.

[12] "CONJUGATED LINOLEIC ACID." WebMD, n.d. Web. 2 July 2013.

[13] "MEDIUM CHAIN TRIGLYCERIDES (MCTs)." WebMD, n.d. Web. 2 July 2013.