Optimum Nutrition Serious Mass Protein Powder, Chocolate Peanut Butter 12LB | Weight Gainer Protein Powder, Mass Gainer with Whey Protein, Creatine, Glutamine, BCAAs, Vitamins & Minerals, Easy Mixing
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Availability:
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Arrives
Wednesday, Sep 9
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Flavor Name: Chocolate Peanut Butter
Size: 12 Pound (Pack of 1)
Features
- HIGH CALORIE WEIGHT GAINER: More than 1,200 calories per 2-scoop serving
- 50 grams of blended protein per 2-scoop serving
- 250 grams of carbohydrates per 2-scoop serving
- With over 20 vitamins and minerals including Vitamin C and Zinc to provide immune support
- MORE VERSATILITY: Using an electric blender, add fresh or frozen fruits, peanut butter, nuts, and other calorie dense foods to boost your weight gain potential
Description
More calories. More protein. More carbs. SERIOUS MASS by Optimum Nutrition serves over 1,200 calories, 50g of blended protein, and over 249g of carbohydrates per 2-scoop serving to help you maximize your daily caloric intake – the ideal post-workout and between meals shake for sizing up your goals. SERIOUS MASS provides you with more tools to help you pack on pounds, when taken in addition to normal calorie intake and over time with regular resistance training.
Product Dimensions : 11.5 x 5.5 x 16 inches; 12 pounds
Item model number : 1056371
Date First Available : December 18, 2013
Manufacturer : Glanbia Performance Nutrition
Best Sellers Rank: #2,074 in Health & Household (See Top 100 in Health & Household) #2 in Sports Nutrition Weight Gainers #266 in Sales & Deals
#2 in Sports Nutrition Weight Gainers:
#266 in Sales & Deals:
Customer Reviews: 4.5 4.5 out of 5 stars (4,956)
Flavor: Chocolate Peanut Butter
Diet Type: Vegetarian
Product Benefits: Immune Support, Muscle Growth, Weight Gain
Protein Source: Whey
Protein: 50 g
Vitamins And Minerals: 0.9, 3.7, 30, 5, 700 milligrams
Supplement Formulation: Multi-Supplement
Total Servings Per Container: 16
Item Weight: 12 pounds
Unit Count: 192 Ounce
Number of Items: 1
Item Dimensions: 11.5 x 5.5 x 16 inches
Brand Name: Optimum Nutrition
Package Type Name: Tub
Age Range Description: Adult
Model Name: ON SERIOUS MASS CHOC PB 12LB
Global Trade Identification Number: 72
UPC: 748927052572
Manufacturer: Glanbia Performance Nutrition
Model Number: 1056371
Manufacturer Part Number: 1056371
Recommended Uses For Product: Calorie Increase, Muscle Growth, Post-Workout, Weight Gain
Allergen Information: Milk, Soy
Material Type Free: Caffeine Free
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Wednesday, Sep 9
This item is non-returnable:
Non-returnable due to Food safety reasons
View our full returns policy here.
Non-returnable due to Food safety reasons
View our full returns policy here.
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Top Amazon Reviews
Flavor Name: Chocolate Peanut Butter
Size: 12 Pound (Pack of 1)
My most recent purchase from Amazon was the protein supplement, Optimum Nutrition Serious Mass. The reason I am writing this review (I usually don’t write reviews, unless the product is exceptional) is because I’ve found this product to be extremely helpful in my fitness goals. As a male in college, I don’t always have a lot of time on my hands. As you can imagine, college students often have varying and complicated schedules that require convenience and on-the-go products for our busy lives. But this product is definitely not only for college students but for people of all walks of life; people who need the right amount of nutrients and calories in a quick and convenient way that tailors to their schedule. I’ve been using this protein shake for quite some time now as this has been my fourth or fifth purchase. I wanted to wait for some time to see if this product does indeed have any positive effect on my fitness goals, so in short, Serious Mass by Optimum Nutrition does work. Who is this for? Serious Mass protein powder is for anyone looking to gain weight in a healthy, convenient, and safe way. It is for people who may need a boost in their weight due to their health situations, for lifters, bodybuilders, athletes, fitness enthusiasts and the list goes on. As for me, I am using this product to add on more weight when I go to the gym to lift and to increase muscle mass. Convenience Naturally, I have an extremely high metabolism. Since I am a hard gainer, to acquire more weight I need to eat a lot throughout the day. Because of time constraints and busy schedules, Serious Mass makes it easy to consume, essentially, a high-caloric meal. How much to use? The directions for this protein shake asks for a serving of two scoops; however, I have found this to be way too much as it is too chunky and thick even with the help of a blender. I suggest to use just one scoop as the scoop that’s included is very large with it being already about 625 calories. You can use this as a meal replacement but for optimal effect, this should be taken in between meals and before bed. Personal Experience I personally have found this extremely beneficial in gaining muscle. Within a couple of weeks to a month there are noticeable gains in muscle growth. As for taste, the protein powder actually tastes good unlike other brands; so far I’ve had strawberry and chocolate, both are very good. The only small issue that I have had with Serious Mass (along with all other protein powder supplements) is the need to use a bathroom relatively soon after consuming this product. As with many protein powder and supplements, it usually increases bowel movement. Then again it can be thought of as a small sacrifice to the greater benefits that are to come. Despite this review being quite lengthy, I truly hope that your goals will be met for whatever situation you try to achieve. As I have found this product very helpful; I hope that it too will benefit you all as well. Best wishes to your health and journey!
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Reviewed in the United States on September 18, 2016 by Amazon Customer
Flavor Name: Chocolate Peanut Butter
Size: 12 Pound (Pack of 1)
Serious Mass really lives up to its name. If you’re looking to put on size, this is one of the easiest ways to get a huge calorie and protein boost in one shake.. The taste is solid (I’ve tried Chocolate and Vanilla), though it’s definitely thick — I usually blend mine with milk or add a banana/peanut butter to make it smoother. It’s filling, so I don’t use it every day, but on heavy training days it’s perfect. The bag is big and lasts a while, though it can be a bit pricey. Overall, a great option if you’re serious about bulking and need extra calories.
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Reviewed in the United States on December 14, 2025 by Kara K
Flavor Name: Chocolate Peanut Butter
Size: 12 Pound (Pack of 1)
Tastes great and includes creatine and glutamine which were two supplements I had to take alongside my previous protein. I add a tablespoon of instant coffee with the serving (2 scoops) of this mass gainer and it tastes really good. The only supplements I take that aren't included in the shake are L-Arginine, Citrulline, and a multivitamin. I suggest either taking a probiotic or eating some yogurt everyday to keep your digestive system in check and get the most out of your increased calories! Everyone talks about protein but they forget about carbohydrates and if you want to get big you need A LOT carbohydrates post workout and throughout the day. As for the price, it may seem high, but, when you consider it includes creatine, glutamine, and it has more calories than a large meal per serving, it is actually an amazing price! Remember to eat a lot of real food throughout the day too. The scoop is HUGE! Do not buy a normal sized (24 oz) shaker cup. You might be able to squeeze it into a 28 oz but I would suggest 32 oz or higher. That being said it actually mixes easier than any protein I have tried, it is just a large volume. Get the chocolate peanut butter flavor and put some instant coffee in there! I mix with water and it tastes awesome. This is probably my new protein long term. As long as you take this only after you workout it seems to all be packed on as muscle at least for me. Obviously if you just sit on a couch and drink this stuff you would get huge. This stuff is all around perfect for skinny dudes and hard gainers like myself. If I had a time machine, I would tell myself in high school to take this stuff! PRO TIP: The scoop is buried in the bag, do not dig around for it like an animal! Open the bag, if you do not see it close the bag and invert it a few times, open the bag again. Repeat until you see the scoop! This stuff is sticky by the way, so you really don't want to dig around in it.
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Reviewed in the United States on March 24, 2017 by Tyler
Flavor Name: Chocolate Peanut Butter
Size: 6 Pound (Pack of 1)
Loads of sugar I understand sugar is calorie but there are other brands that use different calorie content that won’t give that too much sugar feel so I won’t buy this again but great taste it’s a good product if your not sensitive to sugar
Reviewed in the United States on April 15, 2026 by Jeremy Luke
Flavor Name: Chocolate Peanut Butter
Size: 6 Pound (Pack of 1)
Tastes good, good ingredients, price is amazing. Good amount of calories per serving which is exactly what I need when the GLP-1s make me not hungry.
Reviewed in the United States on March 20, 2026 by Matthew Harvey
Flavor Name: Chocolate Peanut Butter
Size: 6 Pound (Pack of 1)
I searched for correct Mass Gainer for me, due to metabolism issues with TBI. Consult your doctor if overcoming trauma. It is helping me a great deal on diet imbalances. It definitely fills the gaps in diet.
Reviewed in the United States on June 9, 2026 by Tim Calhoun
Flavor Name: Chocolate Peanut Butter
Size: 12 Pound (Pack of 1)
I'm enjoying the taste and nutrition, but the bag had a hole in it upon arrival and the mix was all over the box and made a mess. Probably shouldn't be drinking it but have used 6 times now and feel fine. Didn't want to have to return and then re order
Reviewed in the United States on August 12, 2025 by Jennifer H.
Flavor Name: Chocolate Peanut Butter
Size: 6 Pound (Pack of 1)
good
Reviewed in the United States on June 29, 2026 by hao chen