This site may contain links to affiliate websites, and we receive an affiliate commission for any purchases made by you on the affiliate website using such links. Read Our Disclosures
Optimum Nutrition Serious Mass Gainer provides you with 50 g of protein, 252 g of carbohydrates, 4.5 g of fat, and a massive 1250 calories – nearly twice as many as Optimum Nutrition Pro Gainer.
As one of the bestselling sports nutrition weight gainers on Amazon, Serious Mass also delivers 25 vitamins and minerals, 1 g of creatine monohydrate and 500 mg of L-Glutamine. This is designed to boost strength, muscle size, and recovery, but is it a large enough dose to be effective?
In this review we’ll compare ON Serious Mass Gainer to two other high-calorie, high-protein mass gainers; Optimum Nutrition Pro Gainer, and BSN True-Mass. This includes the ingredients, dosages, price, cost per serving, and customer feedback, to help you find the best protein powder based on your fitness goals, bodyweight, and caloric intake.
We’ve also added recommendations for the best pre-workout and BCAA products you can use alongside ON Serious Mass Gainer, to maximize the results from your workouts.
O.N. Serious Mass Ingredients
Optimum Nutrition has taken over the market when it comes to high quality mass gainers, with the introduction of their Pro Gainer and Serious Mass protein powders.
If this is your first time using a mass gainer, the first thing to note is the serving size. At 334 g, it’s more than twice the size of the Pro Gainer servings, and more than 10x the size of Optimum Nutrition Gold Standard.
A quick look at the macronutrient profile reveals where this weight comes from. The 50 g of protein is hardly surprising, but the 254 g of carbs is unlike any other weight gain protein powder on the market. Add this to the 4 g of fat and the result is 1250 calories per serving.
For comparison, the standard BSN True-Mass has 90 g of carbs, BSN True-Mass 1200 has 222 g of carbs, and NOW Sports Carbo Gain powder has 63 g of carbs (but nothing else, no protein).
As for the micronutrient profile, Optimum Nutrition have worked hard to pack in 18 vitamins and minerals at 100% or more of your recommended daily value. This includes vitamin A (5000 I.U., 100% DV), vitamin C (60 mg, 100% DV), and vitamin B12 (10 mcg, 167% DV).
Cholesterol is quite high (80 mg) compared to other Optimum Nutrition protein powders, and the 430 mg of sodium (18% DV) is even more than the 330 mg we saw in their Pro Gainer formula. Calcium content is off the charts for a protein powder, with 630 mg (63% DV) per serving. That’s in comparison to the 8% you get with Gold Standard Whey, or the 15% found in BSN Syntha-6.
If cholesterol or sodium levels are a concern, we would advise checking the flavor before you buy. The numbers mentioned above were for Banana flavor, but for Chocolate Peanut Butter this increases to 95 mg cholesterol (32% DV), and 700 mg of sodium (29% DV).
Maltodextrin and the Protein Blend
Optimum Nutrition Serious Mass has a unique protein blend containing whey protein concentrate, calcium caseinate, egg albumen, and sweet dairy whey.
- Whey Protein Concentrate: Cheaper to manufacture than hydrolyzed whey or whey isolate, whey concentrate is the most common form of whey used in protein powders.
- Calcium Caseinate: Derived from the casein in milk, caseinate is a slow-digesting protein that’s commonly ingested before sleep, so your body has a steady stream of aminos when you’re not eating meals.
- Egg Albumen: A high quality protein derived from dried egg white powder.
- Sweet Dairy Whey: A by-product of cheese making, typically used to replace sugar in recipes due to its sweet flavor.
In addition to the ingredients listed above, each serving also contains 1 g of creatine monohydrate, 500 mg of L-glutamine, 500 mg of glutamine peptides, and 250 mg of choline. But because they’re in such small doses compared to something like MuscleTech NitroTech, we doubt whether you’ll see much of a benefit.
Other ingredients listed on the label include a Vitamin and Mineral Blend, natural and artificial flavors, acesulfame potassium and sucralose as sweeteners, and soy lecithin to improve mixability in water or milk.
O.N. Serious Mass – Product Summary
- High Calorie Weight Gainer: 1,250 Calories per 2-Scoop Serving
- 50 Grams of Protein per Serving
- Over 250 Grams of Carbohydrates per Serving
- 25 Vitamins & Minerals Plus Creatine & Glutamine
- Using an Electric Blender to Add Fresh or Frozen Fruits, Peanut Butter, Nuts & Other Calorie Dense Foods to Boost Your Weight Gain Potential
When is the Best Time to Take It?
Optimum Nutrition describe the optimal usage situations as between meals, post-workout, and before bed. Due to the high amount of carbs we would personally only recommend take a serving after each workout to replenish glycogen stores.
Serious Mass Gainer vs. O.N. Pro Gainer
Serious Mass Gainer vs. BSN True Mass
What Flavors and Sizes Are Available?
With a serving size of 334 grams, each bag provides you with either 8 or 16 servings. Following the recommended use of 1 serving post-workout, the larger bag should be enough to last 1 month, based on 4 workouts per week.
At the time of writing this review, the best value for money larger 12 lb bag. Each serving was priced at $3.00, compared to $4.10 per serving with the smaller 6 lb bag. That’s why we always recommend calculating the average cost per serving, across all sizes, before making a final buying decision.
- Chocolate Peanut Butter
Save Money With Amazon
If you’re looking to save money on your monthly protein powder order, you might want to consider the Amazon Subscribe & Save program.
Subscribe & Save allows you to unlock savings of up to 15% on a wide range of supplements, including O.N. Serious Mass Gainer (certain flavors only).
You can save 5% with a subscription to 1 product, or save the full 15% by subscribing to 5 products, provided they’re all delivered to the same address. The delivery schedule can be set from monthly, up to once every 6 months.
Although 5 products might sound a lot, if you already supplement with a protein powder, multivitamin, creatine, BCAA, and glutamine, the savings can soon add up.
Who Are Optimum Nutrition?
With over 30 years in the sports nutrition industry, Optimum Nutrition currently produces some of the bestselling sports nutrition products in the world. These have been designed to improve your strength and recovery, health and wellness, and help increase your protein intake, such as their Gold Standard 100% Whey.
To find out more about their protein powders, bars, ready to drinks, BCAAs, glutamine, pre-workout supplements, creatine, multivitamins, and weight loss products, we recommend our Optimum Nutrition buying guide. This includes a summary of the health benefits you can expect from each product, which sizes and flavors are available, and dosages for the top ingredients.
We’ve also added in-depth reviews and comparisons with other top rated nutrition companies, to guarantee you only buy the best supplement for your fitness goals.
USA Home Gym gives in-depth insights into gym equipment, supplements, and fitness training methods. The motivation behind USA Home Gym is to provide you with information that goes beyond what you can find in any user manual, customer review, or other online review sites.
We go to great lengths to ensure that our reviews are completely comprehensive, usually covering everything from the design features to the warranty coverage and exercise options. This is all to help guide you towards the home gym equipment that’s best suited to your goals and budget, whilst also being the highest quality option in your chosen price range.