Serious Mass
Optimum Nutrition

Serious Mass

Protein Powder Weight Gainer*
Loaded with 1,250 Calories, 250g of Carbs, & 25 Vitamins and Minerals to Pack on Pounds*
8.6  out of 10  (1,111 Reviews)
2 Sizes
5.4 Kilograms
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6 Flavors
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Price: ¥4,918  (¥307 / Serving)
Flavor Rating: 8.0
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Product Overview

Two Optimum Nutrition bottles standing next to each other.






High-Calorie WeighT GAiner

  • 1,250 Calories per Serving
  • 50 Grams of Protein per Serving
  • 250+ Grams of Carbohydrates per Serving
  • No Sugar Added
Optimum Nutrition Micronizec creatine power bottle

Optimum nutrition true strength

True Strength is a journey. It never rests, it never quits. It's about overcoming obstacles, accomplishing goals, and recognizing achievements. And then it resets to achieve again. As your trusted sports nutrition partner in goal achievement, ON demonstrates that same passion while crafting our products. From the raw materials we source to our state-of-the-art manufacturing processes, no compromises are made. You set the bar higher after every workout, we set the bar higher to redefine the industry standards and ensure you realize optimum results.


Packing a very substantial 1,250 calories into every serving – even more when mixed with cold milk – Serious Mass is the ultimate weight gain formula. With 50 grams of muscle building protein, when used in conjunction with a healthy, balanced diet and regular weight training, this powdered mix provides you with serious weight gaining support for developing your physique to the fullest.*


Optimum Nutrition has been spotting the efforts of goal driven individuals since 1986. As one of the few companies to operate state-of-the-art manufacturing facilities that are GMP compliant, ON assures that every shake will mix up effortlessly because of its first-to-market instantization process. You also expect each shake to taste the same as the last and your next. That's the kind of consistency ON delivers.

History & Heritage

Optimum Nutrition is legendary for both quality and innovation. In addition to producing the world’s best-selling whey protein, ON’s Gold Standard 100% Casein introduced slow-digesting nighttime protein to the weight training world and Amino Energy created the anytime energy category in sports nutrition. When technology makes advancements possible, ON will be the company bringing it to you.

serious mass ideal usage occasions

Ratings & Reviews

Overall Rating
1,111 Ratings
Verified Buyer Rating
423 Ratings
Average Flavor Rating
7 Flavors
Top Rated Flavor
Chocolate Peanut Butter
By clicking the button above, you agree to entering the Reviews section. Products in the Store are not intended to diagnose, treat, cure, or prevent any disease.
Jan 07, 2019
Verified Buyer
  • 10 Chocolate

This is the second time I ordered 12lb serious mass, it is easily dissolved in water and it tastes great. I used it three times a day, each time 1/2 scoop, and I gained 8-9kg in less than 2 months. I suggest it to anyone who wants to get weight.

Jan 06, 2019
Verified Buyer
  • 4 Chocolate Mint
Dec 30, 2018
  • 8 Chocolate

Tastes great but (and its a big one) The protein types in this product are inferior ! No protein isolates and no micellar casein which is poor.. i would opt for the signature mass gainer which has much better formula!

Dec 05, 2018
Verified Buyer
  • 4 Strawberry

takes a while to mix, and straw berry has kind of a medicine/vitamin taste to it

Nov 30, 2018
Verified Buyer
  • 10 Chocolate

Amazing weight gainer for someone who has difficulties putting on serious mass aswell as lack in vitamins. This product tastes great and does wonders. Consistency is very light for someone who isnt used to this type of intake, would highly recommend if youre looking into putting on some serious weight mass/muscle.

Nov 15, 2018
Verified Buyer
  • 5 Cookies and Cream
  • 9 Chocolate
  • 7 Chocolate Peanut Butter

This product works so well, all I would recommend is eat a clean diet around it to keep the bodyfat down as much as possible and also workout hard you'll gain some mass. Also chocolate is the best flavor in my opinion.

Nov 11, 2018
  • 10 Vanilla

On day 47 of 90 the resulting mass is sufficient.

Oct 29, 2018
  • 10 Chocolate
  • 7 Cookies and Cream

Great product to get extra calories throughout the day and bulk up! I recommend taking one scoop at breakfast, and one scoop in the evening (after workout). Pairs very well with a creatine supplement (I use it with Muscletech Creactor capsules). Chocolate tastes great, cookies and cream smells pretty weird and has a chemically after taste.

Oct 17, 2018
Verified Buyer
  • 10 Chocolate Peanut Butter

Best Product ever. Love it.

Oct 15, 2018
No written review.
Sep 21, 2018
Verified Buyer
  • 10 Chocolate

There are several body builders in my family. I have been using this protein for several years now. I haven’t been to the gym in 9 months and lost 10-15lbs. I just purchased another bag because I know I will get quick results. I can’t wait to come home and see it at my door step!! I’m so excited to gain my weight back. I know this mass protein will get me there quick!! Hands down the best!! Good Luck!!

Sep 19, 2018
Verified Buyer
  • 10 Chocolate
  • 8 Chocolate Peanut Butter
  • 5 Vanilla

I had it once per day (one scoop, with breakfast) and was able to gain about 10 lbs in 2 months. The key is not to pack up weight too fast or else most of them are simply just fat.

Sep 06, 2018
  • 9 Banana

I took the banana flavor three times last year. After my second tub I noticed I had definitely filled out more and some of my lifts went up as well. Now that I've been off of it for a year I can tell you that it definitely works. I was up to 185. Now I'm down in the 165-170 range. It does contain a lot of carbs and sodium so if your diet isn't good (mine isn't the best) you will gain fat as well as muscle. You have to work out with it and try and limit your soda and fast food. The banana flavor was good and I used a standard shaker cup. I had no problems with the mix ability. However, the serving size is two heaping scoops which, in my opinion, is overkill. I saved more of the product by cutting the serving down to one scoop or one and a half. Still put on 20 lbs in five months. Would recommend for the hard gainer.

Sep 04, 2018

Cookies and cream flavour: It smells like a cleaning product, the tastes not so bad, though. Better mixed with water than milk. It mixes ok, not great. It seems to have a lot of sugar, because you feel a rush after taking it very noticeable. It works in terms of gains, but I've been using it for 3 weeks and I'm getting pimples all over my face and back. So I'm guessing my body doesn't like some of the ingredients. I'm sure it's this gainer, because that's the only food I've changed in the last 3 months. I keep a very strict diet.

Aug 30, 2018
Verified Buyer
  • 8 Cookies and Cream

Superior product at a great price! The cookies and cream isn't quite as tasty as ather products like syntha6 but easy to put down a few times a day. Gains are very iminent after just a bag.

2.7 Kilograms
2.7 Kilograms
8 Servings | ¥391 Per Serving
Order & Save 10%
5.4 Kilograms
5.4 Kilograms
16 Servings | ¥307 Per Serving

What's in Optimum Nutrition Serious Mass

12 Lbs. Banana
Supplement Facts
Serving Size2 HeapingScoops(334g)
Servings Per Container16
Amount Per Serving In Water % Daily Value
Calories 1250
Calories From Fat 35
Total Fat 4g 6%*
Saturated Fat 2.5g 13%*
Cholesterol 80mg 27%
Total Carbohydrate 254g 85%*
Sugars 21g
Protein 50g 100%*
Vitamin A 5000IU 100%
Vitamin C 60mg 100%
Vitamin D 200IU 50%
Vitamin E 30IU 100%
Thiamin 4.8mg 320%
Riboflavin 4mg 235%
Niacin 50mg 250%
Vitamin B6 5mg 250%
Folic Acid 400mcg 100%
Vitamin B12 10mcg 167%
Biotin 300mcg 100%
Pantothenic Acid 25mg 250%
Calcium 630mg 63%
Iron 5mg 28%
Phosphorus 460mg 46%
Iodine 150mcg 100%
Magnesium 140mg 35%
Zinc 15mg 100%
Selenium 70mcg 100%
Copper 1mg 50%
Manganese 2mg 100%
Chromium 120mcg 100%
Molybdenum 75mcg 100%
Sodium 430mg 18%
Potassium 940mg 27%
Creatine Monohydrate 1g
L-Glutamine 500mg
Glutamine Peptides 500mg
Choline (As Choline Bitartrate) 250mg
Inositol 250mg
PABA (Para-Aminobenzoic Acid) 5mg
* Percent Daily Values are based on a 2,000 calorie diet
† Daily Value not established
Other Ingredients:
Maltodextrin, Protein Blend (Whey Protein Concentrate, Calcium Caseinate, Egg Albumin, Sweet Dairy Whey), Natural And Artificial Flavors, Vitamin And Mineral Blend (DiPotassium Phosphate, Magnesium Aspartate, DiCalcium Phosphate, Calcium Citrate, Ascorbic Acid, Niacinamide, Zinc Citrate, Beta Carotene, D-Calcium Pantothenate, D-Alpha Tocopheryl Succinate, Selenomethionine, Copper Gluconate, Ferrous Fumarate, Manganese Amino Acid Chelate, Thiamin Mononitrate, Pyridoxine Hydrochloride, Riboflavin, Chromium Polynicotinate, Folic Acid, Biotin, Molybdenum Amino Acid Chelate, Cholecalciferol, Potassium Iodide, Cyanocobalamin), Medium Chain Triglycerides, Lecithin, Malic Acid, Acesulfame Potassium, Sucralose, FD&C Yellow #5.
Allergen Information: Contains Milk, Egg, Wheat (Glutamine Peptides) And Soy (Lecithin) Ingredients.

Directions For Serious Mass:

Add two heaping scoops of Serious Mass to a blender filled with 24 oz (710 mL) of water. Blend for 45-60 seconds. Then add a few ice cubes and, if desired, other calorie-contributing ingredients and blend for an additional 30-45 seconds.

Tips: Mixing two scoops of Serious Mass with 24 oz (710 mL) of nonfat or low fat milk instead of water will give you a thicker, creamier, higher-calorie shake. New users may find if beneficial to begin with 1/2 of a serving daily for the first week and then gradually increase to 1 or more full servings several times a day.

Serious Mass is a substantial weight-gain supplement that can be used to feed serious calorie needs in a variety of different ways.

Between Meals: Drink 1/2-1 serving of Serious Mass between meals to maintain positive nitrogen balance and support a high-calorie diet. Post-Workout: Begin drinking 1/2-1 serving of Serious Mass 30-45 minutes following exercise to support maximum recovery. Before Bed: Drink 1/2-1 serving of Serious Mass about 45-60 minutes before bed to provide nutrients to recovering muscle throughout the night.

Note: For best results use Serious Mass combined with intense weight training (3-5 times per week) and a sensible whole foods diet. Also, keep in mind that sufficient recovery between workouts impacts your ability to gain lean mass. Allowing at least 48 hours between workouts involving the same body parts is recommended.

Warnings: Keep out of reach of children. Do not take this product if you are pregnant or nursing a baby. Check with a qualified healthcare professional before using this product if you are under 18 years of age or if you have any known or suspected medical condition(s) including diabetes, hypoglycemia, and/or if you are taking any prescription or OTC medication(s).

* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
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