Search  for anything...
Optimum Nutrition

Optimum Nutrition Serious Mass, Weight Gainer Protein Powder, Mass Gainer, Vitamin C and Zinc for Immune Support, Creatine, Chocolate, 12 Pound (Packaging May Vary)

  • Based on 41,688 reviews
Condition: New
Checking for the best price...
$89.99 Why this price?

Buy Now, Pay Later

As low as $15.00 / mo
  • – 6-month term
  • – No impact on credit to apply
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout.

Payment plans are offered through our trusted finance partners Klarna, Affirm, Afterpay, Apple Pay, and PayTomorrow. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product

Non-returnable due to Food safety reasons

View our full returns policy here.

Availability: In Stock.
Fulfilled by Amazon
Arrives Monday, Jul 13
Order within 19 hours and 13 minutes
Available payment plans shown during checkout
Protection Plan Protect Your Purchase
Checking for protection plans...

Recently Viewed

Flavor Name: Chocolate


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
  • Over 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.

Is Discontinued By Manufacturer ‏ : ‎ No


Product Dimensions ‏ : ‎ 11.5 x 5.5 x 16 inches; 12 Pounds


Item model number ‏ : ‎ 1101529


Department ‏ : ‎ unisex-adult


Date First Available ‏ : ‎ September 16, 2003


Manufacturer ‏ : ‎ Glanbia Performance Nutrition


Best Sellers Rank: #1,309 in Health & Household (See Top 100 in Health & Household) #1 in Sports Nutrition Weight Gainers #153 in Sales & Deals


#1 in Sports Nutrition Weight Gainers:


#153 in Sales & Deals:


Flavor: Chocolate


Diet Type: Vegetarian


Product Benefits: Immune Support, Muscle Growth, Weight Gain


Protein Source: Whey


Protein: 50 Grams


Vitamins And Minerals: 0.9, 3.7, 30, 5, 700 Milligrams, 100, 100, 1560, 410, 44, 59, 80 Percent Daily Value


Supplement Formulation: Multi-Supplement


Total Servings Per Container: 16


Item Weight: 12 Pounds


Unit Count: 192.0 Ounce


Number of Items: 1


Item Dimensions: 11.5 x 5.5 x 16 inches


Net Content Volume: 13.88 Liters


Brand Name: Optimum Nutrition


Package Type Name: Tub


Age Range Description: Adult


Model Name: ON SERIOUS MASS CHOCOLATE 12LB


Global Trade Identification Number: 00


UPC: 748927023800 748927063592


Manufacturer Part Number: 1101529


Model Number: 1101529


Manufacturer: Glanbia Performance Nutrition


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: Monday, Jul 13

This item is non-returnable:

Non-returnable due to Food safety reasons

View our full returns policy here.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
  • PayTomorrow Financing
  • Financing through Apple Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Similar Products

Top Amazon Reviews

    • It helps a lot
Flavor Name: Chocolate Size: 12 Pound (Pack of 1)
Optimum Nutrition Serious Mass is a great choice for anyone looking to gain weight, build muscle, or increase overall calorie intake. The Chocolate flavor mixes smoothly—especially if you use a blender—and has a rich, dessert-like taste without being overly sweet. Each serving delivers a very high amount of calories, protein, and carbs, which makes it ideal for people with fast metabolisms or those who struggle to eat enough throughout the day. It also includes added vitamins, minerals, and creatine for extra support. The bag is large and lasts a good amount of time depending on how much you use. The powder is heavy, so mixing by hand can be a bit difficult, but blending solves that problem easily. Overall, Serious Mass is effective for healthy weight gain and muscle-building goals. If you need a calorie boost and don’t mind a thick shake, it’s a solid and reliable product. ... show more
Reviewed in the United States on December 7, 2025 by Kamila Chirinos
    • Chocolate
Flavor Name: Chocolate Size: 12 Pound (Pack of 1)
ChocolateSize: 12 Pound (Pack of 1) Optimum Nutrition Serious Mass is a great choice for anyone looking to gain weight, build muscle, or increase overall calorie intake. The Chocolate flavor mixes smoothly—especially if you use a blender—and has a rich, dessert-like taste without being overly
Reviewed in the United States on May 6, 2026 by Delano David
    • Awesome protein shake brand! Awesome protein shake brand!
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
Review Image by Ronisha Williams
Love this product. I get sick to where I cant eat this helps me pull back the calories and rebuild my muscles quickly so I dont lose my progress. The taste is good and milky doesn't have soy (which im allergic to) which most proteins contain. There is a chocolate smell that is very pleasant. It dissolves without having to be blended and blends well in my shaker bottle. ... show more
Reviewed in the United States on May 2, 2026 Reviewed in the United States on May 2, 2026 by Ronisha Williams
    • Like I said 1250 calories per serving and that is ...
Flavor Name: Chocolate Size: 12 Pound (Pack of 1)
I work for the USPS so I walk miles and miles a day. Making it hard for me to gain or maintain a healthy weight. I eat a lot but my metabolism its too fast for me to keep up with it too. Here is what I think about this protein powder. 1. It makes you gain weight. I took it for a week every day before bed and gained from 5lbs in almost 2 weeks. I did have to mix it with other stuff just to bump up the calories count. Note that it says 1250 calories per serving that means 2 scoops of protein powder and the scoop is huge as it is. It is kind of hard to include other things other than milk because each serving has so much protein powder already that sometimes you end up with a huge huge protein shake. 2. What's in ever scoop? Whey protein, casein, vitamins, minerals, and essential fatty acids to help you pack on the pounds without gaining fat. It also delivers 1000 mg of creatine monohydrate (a nitrogenous organic acid that supplies muscles with essential fuel). Like I said 1250 calories per serving and that is if you mix it with water. If you chose milk its about 1650 calories per serving, but it varies depending on what kind of milk you prefer. 3. How does it taste... the taste is a very super rich and thick chocolate taste. I don't know how to describe it, but the taste is delicious I promise. The only reason why I didn't rate this product with 5 stars its because it kind of gets a little pricing since each package has only 16 servings. For me it works because as soon as I gain my desire weight its easy for me to keep up with it by just drinking half of the serving size once a week. Another thing that I didn't like is the bag is huge and hard to storage or to move around. I had to split mine into 3 parts. What bother me the most is the texture and form of the powder. It's very thin almost like dust (not really, but kind of). Every time I try to make a shake the powder gets all over the place because the scoop is so big for my ninja blender. So it does get messy have fun trying to make a shake right before work without getting it on your clothes or without making a mess. ... show more
Reviewed in the United States on March 7, 2016 by marcog
    • Great price & product.
Flavor Name: Chocolate Size: 12 Pound (Pack of 1)
Great price! Fantastic product. My husband is 63 and started using up his muscle mass. This works perfectly in his routine. He is a hard working contractor.
Reviewed in the United States on May 12, 2026 by Karla Woodis
    • 10/10 for quick weight gain
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
Helped me gain weight in a quick period. Will order more to get to my weight gain goal. Easy to mix, yummy with a banana added 🤗
Reviewed in the United States on May 6, 2026 by Kayla Standley
    • Serious Mass
Flavor Name: Chocolate Size: 12 Pound (Pack of 1)
I’ve only gotten this product yesterday but so far I’m happy with it. Mixes fairly well in a protein blender bottle, chocolate flavor tastes smooth, and almost 700 calories per scoop. I mix it with lactaid milk and water and my body hasn’t had a problem with digesting.
Reviewed in the United States on April 18, 2026 by Randy
    • What They Don't Tell You What They Don't Tell You
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
Review Image by Tera R
What they tell you. It tastes great and is a good supplement to build mass. What they don't tell you. Each serving consist of 2 huge heaping scoops of powder and 24 ounces of fluid (water or milk). This combination results in 48 ounces of liquid delight that they claim is a single serving. On what planet is 48 ounces a single serving? To put this in perspective, that is 2 full to the brim Shaker bottles that are intended to be consumed as one serving. 340 grams of powder from one serving translates into 3/4 of a pound of powder. Again to put this into perspective, the huge tub of powder you will recieve equals ONLY 8 advertised servings. The other thing they don't tell you is the powder is so fine and gummy that the only way to prepare the drink is to use a full sized blender. No Shaker bottles here. Preparing this mix is a mess. The powder is so fine that it creates a gummy mess that adheres to the side of the blender like Venom on Eddie Brock. Prepare to spend a significant amount of time coaxing the paste free to get it to properly mix. Great protein mix, but I sometimes I feel like it would be easier to eat 5 chicken breasts too reach the same calorie goal, than to put down 48 ounces. I realize that it can be broken up throughout the day, but so can multiple meals. There is also the option of using another protein supplement with a realistic serving size, multiple times a day. In the end, I feel like that is all they have done with this product. They have combined a multiple dose, throughout the day protein powder into a single serving, trying to advertise it as a solution that they obviously have not solved. ... show more
Reviewed in the United States on December 9, 2023 Reviewed in the United States on December 9, 2023 by Tera R

Can't find a product?

Find it on Amazon first, then paste the link below.
Checking for best price...