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*
8.4 out of 10 (1,137 Reviews)
2 Sizes
2.7 Kilograms
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5 Flavors
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Price: $27.48 ($3.44 / Serving)
Flavor Rating: 7.5

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
1,137 Ratings
Verified Buyer Rating
413 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.

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Verified Buyer
  • 10 Chocolate Peanut Butter

Been using this for about 3 weeks now..... if you cant eat food or are not a big eater and need to put on weight, this makes it too easy... I simply do 1 scoop with 2 cups of whole milk and 2 tb spoon of peanut butter and thats 1143 calories, my goal each day is 2660 to gain 1 lb per week and with this shake i easily get that number having 2 a day (both 1 scoop instead of the 2 it says to use). Would definitely recommend to anyone who thinks its hard to gain weight to use this.... I'm 23 and struggled with gaining weight all my life and this is making it almost too easy.....

Verified Buyer
  • 9 Chocolate
  • 10 Cookies and Cream
Verified Buyer
  • 10 Vanilla

Great Product

  • 10 Chocolate Peanut Butter

This is probably one of the cheaper weight gainers in the market. A ton of carbs, ideal for those who have fast metabolism. This product doesn't make me bloat and it is the best weight gainer I have tried in term of taste. I would still prefer Pro Gainer if they were cheaper. Also this product is packed with vitamins. So the combination of vitamins and very affordable price makes this product deserves at least 8.

  • 9 Chocolate

12LB Serious Mass Chocolate flavor taste good , mixed with milk is awesome

  • 3 Banana

12lbs of serious mass can run if i take 2 scoops in one day 1 in morning and 1 in evenign

Verified Buyer
  • 9 Vanilla
  • 3 Banana
  • 10 Strawberry

It’s agreat product it really does gain muscle mass gained a solid 7+ lbs within 3 weeks.. banana tastes like juicy fruit gum . I got banana and strawberry to mix together in shakes not greatest idea.. vanilla is delicious and it’s the way to go.

Verified Buyer
  • 9 Chocolate Peanut Butter

I was quite impressed with the taste,however I did just buy two 45oz shaker bottles. That being said if I had it in a normal sized bottle it would have been like drinking pudding. This is a mass gainer for skinny guys like me with a fast metabolism,with 1270 calories and 249 grams of carbs. Having 249 grams of carbs I would not recommend if you just trying to put a little size on , this will make you fat. It is high in sugar , 26 grams with water with low fat milk it has 61 grams of sugar !

Verified Buyer
  • 8 Chocolate Peanut Butter

The bag was sealed incorrectly making it impossible to open so I had to cut a hole in it to get the powder out. Also most of the powder coagulates to the the top of the milk making much of it go to waste. Skip this product

Verified Buyer
  • 4 Vanilla

I am 48 years old, and the older I get the more my appetite decreases. I can’t put away the food I once did and protien by Optimum really helps in maintaining my weight. With working out I even put on 15 lbs of muscle with this powder. I think the vanilla flavor is the best tasting vanilla I ever had. Great with mixing with fruits etc or just by itself. Love this product and love the price! It is the protien I will always use.


If your looking to gain extended mass or weight this is a Great Option, if you Put in the intensity, Ectomorph go too Product, therefore if you Don't have an Effective workout plan, or A Measure of how your a metabolism and Body Composition works, you"ll find Quiet a Few Buttheads in the Reviews

Verified Buyer

Do yourself a favor and get the big 42oz blender bottle.. I never needed a blender again. Considering the price and the quality of the company, this is my go-to bulking powder. I found most success waiting until an anabolic window opens before consuming, I metabolize it much quicker and don’t feel sick or rushed to the bathroom. Forcing this down is the worst thing in the world as is any bulking supplement. Splitting it into two 1-scoop servings is also a great way to ensure your metabolism stays in check. If you’re lifting weights and want to see changes you’ve found the product you need.

Verified Buyer
  • 10 Chocolate

great tasting, good for gaining if you have a really fast metabolism like me

  • 6 Vanilla

Personally feel eating more food is the better route. Was thinking drinking the extra calories to get bigger would be a easier alternative, but the serving size of serious mass is a bit ridiculous. looks scooper looks like what I use for laundry detergent. Just personal opinion.

What's in Optimum Nutrition Serious Mass

6 Lbs. Banana
Supplement Facts
Serving Size2 HeapingScoops(334g)
Servings Per Container8
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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