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  (1,088 Reviews)
2 Sizes
6 Lbs.
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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
1,088 Ratings
Verified Buyer Rating
412 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.
  • 1 Chocolate
Verified Buyer
  • 10 Chocolate Peanut Butter

Used to use about a year ago to put on some size, gained roughly 5 lbs in my training routines and have purchased more. Looking forward to my next order of Serious Mass.

Verified Buyer
  • 10 Chocolate
  • 9 Chocolate Peanut Butter
  • 9 Banana

Excellent product, does exactly what it says on the tin. Tried the chocolate, chocolate peanut butter and banana. Taste wise chocolate is my favorite but all those 3 taste good. Gives plenty of energy, protein and vitamins/minerals. Can't say I've tried any of the other brands but I don't need to as this does exactly what I need, great stuff even if a bit pricey.

Verified Buyer
  • 10 Chocolate Peanut Butter

This product taste very good and it did it job. I would recommend this product if you wanna put some serious mass on.

Verified Buyer
  • 8 Vanilla

Flavor not bad this product along with weight training help me gain 9lbs in 1 month

Verified Buyer

Been using this for two years, Helped me gain 15 lbs. Not a big guy so I needed to increase weight in order to lift more. Great flavor. I add peanut butter and banana to two scoops and use vit d milk instead of water.

  • 1 Vanilla
Verified Buyer
  • 10 Banana

I bought the banana flavor to consume while in recovery from my tonsillectomy. I think it tastes simply amazing! The product does not feel too thick or heavy. I can easily drink a whole serving in one sitting and enjoy it, and it pretty much covers my hunger for the next few hours. The only complaint I had was that the packaging came damaged and leaking. However, the product and flavor were so good that this was a non-issue for me.

Verified Buyer
  • 10 Chocolate

This stuff is the best mass gainer out right now. Has all the vitamins and minerals you need in a daily diet and helped me gain 15 pounds!

Verified Buyer
  • 9 Banana
  • 9 Strawberry

Put it this way, i can down a 2 scoop shake in about a minute, however I am used to a very high calorie intake, for someone new to this, you might find it a little harder to do so, the flavour is good, its a thin shake in comparison to other competitors and trust me I have tried almost all of them, yet i find myself coming back to this one. Please do not think this is a miracle shake, you need a balances diet to get the benefits from this shake, if you have a set meal plan and your diet matches your ambition you will gain, fast. put it this was on 13/01/17 i weighed 40kg, as of today I weigh 83kg. Hard work, many gym sessions a week, and a lot of pain. I use the JYM protein shaker 500ml of water and two heaped scoops keeps it thin to make it feel like a normal whey protein shake.

No written review.
Verified Buyer
  • 10 Vanilla

To begin this Serious Mass is serious ON is right on that honestly one full scoop of this will full you up well that’s for me. I usually drink it with in meal or after a tough exercise but god this sure has a lot of calories to make me full. I been seen progress just like Pro gainer them too are on point with high protein just wishing I could mix them together but sadly pro is 16oz and serious is 24oz so have to take it separate. I recomendé if your trying to feel full or just getting bulky.

Verified Buyer
  • 9 Chocolate Peanut Butter

One of the best products I have ever used! Helped me put on a good amount of weight especially since I have a hard time putting down large meals. I only took a half a serving at a time (1 scoop) with whole milk and it gave me more than enough protein and carbs to get my calories up where they need to be. Takes a while to mix but I don't have the largest shaker cup so a little more milk or water or whatever you mix it with could solve that easily. Flavour was amazing and it was really thick but without causing bloating or an upset stomach. Highly recommend!

  • 10 Chocolate
  • 8 Chocolate Peanut Butter

So far so good. I'm 6'4 and weighted 170. Now almost 2 months into my new routine using Serious Mass I'm at 182 pounds and growing. Couldn't be happier with the product as I'm finally seeing some real results after being a tall, lanky guy my entire life. Highly recomended!


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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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