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*
8.5  out of 10  (1,135 Reviews)
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For a limited time, buy 1 Serious Mass, 6 Lbs. & get 1 20% OFF!
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For a limited time, buy 1 Serious Mass, 12 Lbs. & get 1 20% OFF!

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

Serious Mass
Overall Rating
1,135 Ratings
Verified Buyer Rating
441 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.
Dec 20, 2019
  • 10 Banana

it works! not much more to say!

Nov 23, 2019
Verified Buyer
  • 9 Chocolate

it tastes good

Nov 19, 2019
  • 9 Cookies and Cream

nice product <a href="#">serious mass</a>

Nov 13, 2019
Verified Buyer
  • 8 Vanilla
Nov 02, 2019
Verified Buyer
  • 7 Chocolate

Last year, I started going to the gym 3 days a week for lacrosse. I'm a teen, I've been growing quite a lot. Last year I was 5'7 at 115, So somewhat small, but once the year was over I was 6'0 at 125. I didn't really know how to gain weight fast enough to keep up with my height. This lead to me seeing very little progress in the gym and in my overall physique. I really hated getting called skinny and underperforming in the gym so I decided I needed to gain some weight. I started using this about a month ago, starting at 130lb, and now I'm 140. I didn't just use the shake alone though. My recipe is as follows: *16oz of milk *3-4 tablespoons of peanut butter *One cup of protein powder (half the overall serving size) *1 banana *and 3ish scoops of chocolate ice cream (I know it's not great but it tastes like sh*t without) -Overall calories for this is around 1700 and the protein is 62g I take two of these a day along with my normal diet so I'm taking in around 5000 calories a day. I'm also training 4 days a week with 1-2 days of cardio a week So if you're trying to bulk and are skinny, I would recommend

Sep 22, 2019
Verified Buyer

Very Good Product. I recommend it. I have a question though, the expiring date is DD/MM/YY or MM/DD/YY? Thank you in advance for your help

Sep 13, 2019
Verified Buyer
  • 10 Vanilla

Vanilla is the best flavor and it mixes well with water, milk or in smoothies. Definitely prefer this over the Optimum Pro Gainer.

Aug 17, 2019
Verified Buyer
  • 10 Strawberry

I’m happy with this product. Best food for my muscles 👍

Jul 13, 2019
  • 10 Chocolate

So, I was about 53kg and I started gym seriously in January 2019 and started taking this and within 3 months of taking and finishing the product, I gained 20kg.

Jul 12, 2019
  • 10 Vanilla

This stuff is a game changer. I went from making home made weight gain shakes using bananas peanut butter and nuts and being on the toilet for days while switching to this and really seeing results. I gained a lot of mass since taking this as well as eating more and I have to say this stuff is incredible. I really see a difference when I stop taking it as I become like a raisin but this keeps my shoulders broad and bulked up. Now the flavor isn’t great let’s be honest and the fact it froths up and you have to wait at least an hour for it to turn to liquid is a little annoying but honestly when your an extomorph and you need to gain weight you’ll deal with it cause this product does work. It’s even better when you add bananas and strawberries or even blueberries taste good with it. I try to drink this five days a week at least it’s my holy grail , and really has helped me a lot so thank you serious mass. I went from skinny and eating everything never seeing any results to actually gaining weight . From a skinny twig this is a game changer thank you!!!

Jul 03, 2019
  • 10 Banana


Jun 20, 2019
Verified Buyer
  • 2 Chocolate

The chocolate taste is terrible! It’s the only reason for a low review.. we’ll see if the product helped in 5-6 weeks

Jun 18, 2019
Verified Buyer
  • 9 Chocolate
  • 7 Chocolate Peanut Butter
  • 2 Banana

Alright so the product itself is the best going around & if you workout 4-5x/week, taking 1-3 FULL servings/day (approx 3500 cals/day) from this Mass Gainer will get you SERIOUS MASS. I started with 140lbs & gained close to 30lbs in 2 months of heavy diet (whole foods) + this product. Now about the flavors: 1) Banana: stay away! This was my first flavor & had to ask for a return but they don't do returns out of the US so had to finish the bag somehow. Almost felt like throwing up after every serving. 2) Chocolate: BEST I've tried so far. It's not too sweet, not too thick & tastes very pleasant. Easy to finish the bag. 3) Chocolate Peanut Butter: Just fine. Wasn't as good as Chocolate but was nowhere as bad as Banana. If you like your chocolate drinks sweeter, go for this one as it is definitely sweeter than the regular Chocolate flavor.

Jun 13, 2019
Verified Buyer
  • 10 Chocolate Peanut Butter

Ordered this 3+ times so far and its great results if you're consistent with drinking it at least once a day. Drank it 2-3x a week and was still able to gain 5lb in 2months and i have fast metabolism too. Flavor is great, way better than any i've ever tasted and i've tried the vanilla and cookies and cream but still doesn't beat this. I mix it with soy milk cause i'm lactose tolerant. i'd for sure recommend putting in a few ice cubes to make it less thick

Jun 10, 2019
  • 10 Chocolate

Being 7 stone for a very long time struggling all my life with my weight because I have an overactive thyroid problem. Being 5ft 5 and the weight I was at I was allways asking my doctor about stuff to help me gain weight and they allways said there was nothing they could do. One day someone just say to me you look Ill & I just had enough. So I searched for products what could help me and I come across this product.. and all I can say after a month of having it. I have little tyres on my belly and I’ve never been so happy in my self I feel like I can do more in work I’m not as weak just all around brilliant product I’ve just finished my first bag I’m gonna recur it every month. Thankyou serious mass I love it I couldn’t rate it enough flavour is amazing but use a blender it’s just like a makkies shake.

2 Sizes
12 Lbs.
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Price: $56.99  ($3.56 / Serving)
Flavor Rating: 7.8
Loaded with 1,250 Calories, 250g of Carbs, & 25 Vitamins and Minerals to Pack on Pounds*

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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