Review of Optimum Nutrition Pro Complex Gainer

A comprehensive review of the Optimum Nutrition Pro Complex Gainer whey protein product. Is it among the best muscle building supplements?

Rating: 4.5 (out of 5)

Welcome to this review of the Optimum Nutrition Pro Complex Gainer whey protein supplement product. Optimum Nutrition is one of the most well regarded sports nutrition supplement manufacturers in the world.

Founded in 1986, the company is now a wholly-owned subsidiary of Kilkenny, Ireland-based Glanbia Corporation.

Optimum Nutrition offers a full range of vitamin, sports and muscle building supplements covering the full gambit of supplements. It is a major player in the $30 billion a year supplement ON Whey Protein Powderindustry, and their products are very well accepted. (You can read more reviews of their whey protein powder products on this page within this site here.)

Let’s now get into this offering by Optimum Nutrition and their Pro Complex Gainer supplement.

 Product Features of ON Pro Complex Gainer

The ON Pro Complex Gainer whey protein powder, like all of Optimum Nutrition’s products, is manufactured in cGMP-compliant (current Good Manufacturing Practices) facilities. This is highly desirable as this is the highest standard possible.

Optimum Nutrition’s in-house manufacturing operation has been registered under the NSF International, The Public Health and Safety Company, Good Manufacturing Practices (GMP) Program.

What dos this mean in practical terms? It means that their product raw ingredients are tested for impurities and that all of the manufacturing elements meet cGMP guidelines. This means a high degree of final product purity before it’s wrapped and shipped.NSF Certified for Sport

The US FDA doesn’t oversee supplements, their are pros and cons to this, so this NSF cGMP certification goes a long way in establishing quality and ensuring product safety.

NSF Certified for Sport registered GMP certification is what to look for in supplement companies as not many have this. Optimum Nutrition does. In truth, supplement fraud is rampant so this is highly desirable. The cGMP compliance. Again, that is highly desirable and an indicator of high product quality. These requirements are consistent with the published GMP regulation for dietary supplements as defined in 21 CFR § 111, which was published by the FDA in June 2007.

Let’s talk now about the nutrition profile of the Pro Complex Gainer product.

It is made from seven proteins including casein, egg, milk, and whey.

Each serving gives 270 calories and 60 grams of protein. Of those calories, 10 are from fat. (Most whey protein powders give 20 to 30 grams of protein so this product is clearly targeting those who need more protein in their diet.)

complex1ON Pro Complex GainerIt gives 15 vitamins and minerals, 14 grams of BCAAs (branched chain amino acids), and 10 grams of glutamine. Moreover, this formula is designed nutritionally to help synthesize lean muscle mass as indicated by its high protein to carbohydrate ratio.

How about its flavor options? The ON Pro Complex Gainer comes in rich milk chocolate, strawberry cream, double chocolate, banana cream pie, and vanilla custard.

What sizes does this product come in? It is available in 4.6 pound, 5.08 pound and 10.16 pound canisters.

How Much is ON Pro Complex Gainer?

I’ve researched all over the Internet and offline, brick-and-mortar supplement stores and the best prices I can find are at You can buy it here, but you are free to choose.

On Amazon, the price ranges for the product and size options are as follows:

Does It Include a Guarantee?

Yes, it does. Optimum Nutrition guarantees all of their products, but they usually defer to the retailer who sold the product and their guarantee. I recommend buying from if you’re interested as they 1) have the best prices and 2) they have a great guarantee. Amazon is the largest online retailer in the world and are renowned for their customer service. You can read about their guarantee here, if interested.

Consumer Testimonials About Pro Complex Gainer

Below are some testimonials where you can read about the product from actual users. You can read more testimonials here.

Great Amount of Carbs, Protein, Vitamins, and Taste…Low Sodium & Cholesterol
By Doug on March 24, 2010
Amazon Verified Purchase

After much research, several years ago I started using this muscle-gainer and have enjoyed it ever since. To me it is almost the perfect work-out / weight-lifting / energy / muscle-gaining drink. It has a great amount/ratio of carbs (85g … only 5g in sugars), protein (60g .. several types), vitamins/minerals (usually only 20%-35% RDA … some drinks put in 100% in many areas but I want to use a multivitamin, GNC Mega Men, instead), and taste (I have enjoyed my favorite banana, strawberry, and vanilla). It also has low sodium (15% RDA) and cholesterol (20% RDA) relative to many other drinks I saw, which are quite high in these areas … beware.

I don’t drink it every day, just usually about half a serving before a workout and half after. That gives me enough carbs/energy to enjoy the workout and then protein after for good/reasonable muscle growth, all the while staying low in body-fat. It easily mixes with lowfat milk or soy milk, and tastes good with both. I’d give it 6 stars if I could.

High Quality Calorie Gainer/Meal Replacement
By F. RADDATZ on September 3, 2011
Flavor Name: Vanilla Custard
Size Name: 10 Pound Amazon Verified Purchase

As an amateur/hobby bodybuilder, this single product has become a staple in my diet over the past 3 years. When I started getting serious about lifting again out of college, I had dropped to 145lbs from my previous high of 175lbs. My metabolism is fast, and I simply had trouble keeping up for a Protein Shakesnumber of reasons: time, money, and the difficulty eating the calories I needed in solid foods. I then found this product, which has helped all three of those issues.

VALUE – At approximately $2.25 a serving (when using subscribe and save), this is one of the cheapest quality 650 calorie meals you can provide your body with. I found this to be much more cost effective than trying to put together my own meal. Thanks to Amazon’s subscribe and save, the prices compete with the other bigger online supplement retailers and I don’t have to worry about re-ordering.

PERFORMANCE – I can drink an entire serving in 2-5 minutes without feeling bloated/sick (taste ranges from acceptable to good – banana cream and vanilla are must tries). I have one serving every morning, and one at some point after my workout and before bed. This accounts for 1300 of my 3500 daily calorie intake. For me, without the aid of liquid weight gainers – it would be impossible to achieve my calorie goals and gain lean mass. I especially would struggle in the morning — I often don’t have time to prepare a good meal, and have trouble eating too many solid foods first thing in the morning. Also – understand that while 60 grams of protein a serving may seem like too much, this is not 60 grams of pure whey protein that is metabolized very quickly. It is packed with 7 sources of protein (faster and slower metabolized proteins) so it takes several hours for your body to metabolize the protein.

As you can see, this is a well received product. At Amazon, there are 116 reviews, scoring a 4.7 out of a possible 5.0. At another health website, this product has 422 reviews scoring a 9.3 out of a possible 10 (anything 8 or higher is generally seen as very good). Clearly this product is doing what it is purported to do judging by the customer commentary, which is more indicative and precise than any marketing copy.

Are there any customer complaints? Not really. Some don’t think the taste is too great, but others do. With some it gives flatulence, with others it doesn’t. Overall, this is a very well received product by serious bodybuilders and fitness enthusiasts who have extra protein needs.

The one complaint that is fairly brought up is its price. Many think it’s expensive but are willing to pay the price if it gives the gains ON promises and it appears as if it does, judging from the customer testimonials I’ve come across.

Where Can I Buy Pro Complex Gainer?

ON Protein PowderYou can buy it here at Amazon, but you are free to choose. Is the ON Pro Complex Gainer the best whey protein powder? That is certainly debatable as there are many formidable competitors out there, but one thing is certain — this is a high quality product that is made with rigorous GMP standards and is well received in the marketplace.

I hope this review of the Optimum Nutrition Pro Complex Gainer product has been helpful to you.

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