Serious Mass Weight Gainer
Optimum Nutrition

Serious Mass Weight Gainer

High Energy Protein Powder Contributing to Muscle Growth
Loaded with 1258 kcal, 250g of Carbs, & 25 Vitamins and Minerals
8.5  out of 10  (1,152 Reviews)
Free Gift

Get a Free ENGN, 30 Servings, Fruit Punch When You Spend £24 or more

*You must add ENGN, 30 Servings, Fruit Punch to your cart to get it for free.

Save an additional 10% off as a Bodyfit member. SIGN IN or JOIN TODAY!

Save 20%
Order and automatically receive 20% Off in your cart on Serious Mass Weight Gainer, 12 Lbs.!

Save an additional 10% off as a Bodyfit member. SIGN IN or JOIN TODAY!

Save 20%
Order and automatically receive 20% Off in your cart on Serious Mass Weight Gainer, 6 Lbs.!

Save an additional 10% off as a Bodyfit member. SIGN IN or JOIN TODAY!

Product Overview

Serious Gains Serious Taste!

Gold Standard Whey Container

Serious Mass is the ultimate in weight gain formulas, with 1250 calories per serving and 50 grams of protein to support muscle growth and repair. This instantised powder makes the ideal post work-out and between meals shake for sizing up your goals.

Serious Mass provides you with the tools you need to pack on the pounds and when coupled with serious weight room effort develop your physique to the fullest.

24g Protein

50g Protein

Tasty Foods

Muscle Support


1250 Calories


Weight Gain

Ratings & Reviews

Serious Mass Weight Gainer
Overall Rating
1,152 Ratings
Verified Buyer Rating
451 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.
Mar 02, 2021
  • 10 Chocolate

Great product! I felt I started gaining weight two days later after I started consuming. It can be easily digested but causes some bloating. I drank it before bed for weight gain. I gained 3 kg within a week, also The taste is very good.

Feb 11, 2021
  • 8 Chocolate

Hard to get the whole shake down, however using whole milk, bananas and sometimes peanut butter makes the taste better and adds cals. Tastes pretty good

Feb 05, 2021
  • 8 Chocolate

this product is a whole cheat code for bulking if anyone asks me for any tips on bulking this is what i tell them about!

Dec 26, 2020
Verified Buyer
  • 10 Chocolate Peanut Butter

This is the best mass gainer I have tried. Great blend-ability. Been using it roughly twice a day between meals and the results a obvious. Starting about 4 months ago I have now gained 10lbs and my goal of benching 225lbs x 20 has been surpassed to completing 21 rep sets now. I began at 13reps. Overall body size has increased dramatically.

May 29, 2020
  • 10 Chocolate Peanut Butter

I am using these product from last 2 weeks while its amazing product. I recommend to everyone use this product

May 28, 2020
Verified Buyer
  • 10 Chocolate
  • 5 Vanilla

The Vanilla flavor is a little chalky once it comes to texture however, other than that once blended with the right mixtures, it"s flame! The Chocolate flavor is enjoyable. You DO get Results from this product as well, after a solid use of 3 months accompanied by intense work outs.

Apr 24, 2020
  • 10 Chocolate

Flavour is great, tastes like chocolate milk. Scoops are large I did half servings morning and afterworkout/evening.

Apr 22, 2020
Verified Buyer
  • 8 Chocolate Peanut Butter

I started at 162LBS (6'2') and after taking this twice a day (1 scoop each time) I'm weighing 170LBS. about to order again and planning to eat more as well. Heres how I did it-- one scoop, 16 ounces of whole milk, a 3 scoops of ice cream, .. sometimes I would throw a banana or a tablespoon of peanut butter but that always made it hard to get down.

Apr 17, 2020
Verified Buyer
  • 10 Chocolate Peanut Butter

This is gonna help so much for me and I'm so glad I finally got mine! Just had a curious questions my nutritional facts are the one from Vanilla (I think) but I got chocolate Peanutbutter, but its no biggie, they aren't much different from nutritional facts, but taste is obviously different, im for sure going to buy another bag of this! Totally recommend for people who can't put on weight or trying to bulk up!

Apr 17, 2020
Verified Buyer
  • 10 Vanilla

Ive been taking this product about two months..1 serving after my workout with cell tech creatine fruitpunch at 8am and the second serving around lunch time and i must say I've gain around 12 to 15lbs easy...but you have to put the work in...working out..and all i do is push ups and this product is the real deal!!..and i eat my 3 regular meals a day..breakfast..lunch and if you want the gains..use this product and cell tech creatine fruitpunch WORKKKS!!!

Mar 27, 2020
Verified Buyer
  • 9 Vanilla

I use a scoop of this (625 cal, 25g of protein) and a scoop of syntha-6 vanilla protein. I blend it, and it comes out to 825 cal, 47g of protein after my afternoon workout. The flavor that comes out of this is awesome, tastes great and is filling as heck. Serious mass alone flavor is great too, I've put on roughly 13 pounds in 3 months, a lot of muscle but some fat included. It's just what happens unless you are tracking your exact macros/etc which I don't. Happy with this product

Mar 24, 2020
  • 9 Chocolate Peanut Butter

Really good mass gainer which helped me get 15 pounds of weight. I really like the chocolate peanut butter flavour. I took 2 scoops of mass gainer twice a day and beleive me it has seriously good results.

Mar 16, 2020
Verified Buyer
  • 8 Chocolate

Great weight gainer- helped me put on 10kgs in just a few months. Doesnt mix particularly well, so I'd recommend a blender if possible. Choc Mint flavour has some poor reviews but I really like it (although it kinda grew on me- the first time I didn't like it that much). I split the portions into 2, as 1200 calories in a single hit is quite a lot. I have half a serving twice a day and have definitely reaped the rewards (especially coming from someone who struggles like hell to put on any weight). 10/10 would recommend.

Mar 10, 2020
Verified Buyer
  • 9 Chocolate Peanut Butter

Bomb *** flav

Feb 23, 2020
  • 10 Chocolate

I’m very sensitive to Proteins or Mass Gainers because of the ingredients and always get migraines leaving me sick for days while taking them. But ON products don’t do that to me. And being a hard gainer I need that few hundred to thousand extra calories in my diet, ya’ll know what I’m talking lol Taking this while on a solid diet and a solid work out routine has helped a lot to gain weight. It’s always going to be a struggle for a hard gainer even while taking a mass gainer but if you are consistent then it will pay off.

2 Sizes
2.7 Kilograms
Choose a Size
{{group.violatorText}} {{}}
4 Flavors
Choose a Flavor
Flavor Rating: {{sku.flavorRating | flavorRating}}
Save 20% in Cart
Was:  {{}}
Price: £27.08  (£3.38 / Serving)
Flavor Rating: 7.9


Become a BodyFit Member

BodyFit Membership means up to 10% OFF EVERYTHING and FREE shipping.

Oh... and you also get:

• Access to exclusive workout plans and database

• Detailed exercise instructions

• Customized recommendations for all your fitness goals

Get free shipping and save an additional 10% on today's order

Loaded with 1258 kcal, 250g of Carbs, & 25 Vitamins and Minerals

What's in Optimum Nutrition Serious Mass Weight Gainer

6 Lbs. Banana
Serving Size About 2 Heaping Scoops (336 g)
Servings Per Container8
Amount Per Serving In Water % Daily Value
Calories 1,250       
Total Fat 3.5 g 4%*
Saturated Fat 2 g 11%*
Cholesterol 105 mg 35%
Total Carbohydrate 254 g 92%*
Total Sugars 20 g **
Includes 10g Added Sugars 21%
Protein 50 g 100%*
Vitamin A (as beta-carotene) 940 mcg 104%
Vitamin C (as ascorbic acid) 60 mg 67%
Vitamin D (as cholecalciferol) 5 mcg 25%
Vitamin E (as d-alpha tocopherol succinate) 20 mg 133%
Thiamin (as thiamin mononitrate) 4.8 mg 400%
Riboflavin 4 mg 308%
Niacin (as niacinamide) 50 mg 313%
Vitamin B6 (as pyridoxine hydrochloride) 5 mg 294%
Folate (as folic acid) 680 mcg 170%
Vitamin B12 (as cyanocobalamin) 11 mcg 458%
Biotin (as d-biotin) 300 mcg 1,000%
Pantothenic Acid (as d-calcium pantothenate) 25.6 mg 511%
Choline (as choline bitartrate) 250 mg 45%
Calcium (as calcium citrate, dicalcium phosphate) 640 mg 49%
Iron (as ferrous fumarate) 6 mg 33%
Phosphorus (as dicalcium phosphate, dipotassium phosphate) 490 mg 39%
Iodine (as potassium iodide) 53 mcg 35%
Magnesium (as magnesium aspartate) 125 mg 30%
Zinc (as zinc citrate) 15 mg 136%
Selenium (as selenomethionine) 71 mcg 129%
Copper (as copper gluconate) 1 mg 111%
Manganese (as magnesium aspartate) 2 mg 87%
Chromium (as chromium polynicotinate) 120 mcg 343%
Molybdenum (as molybdenium amino acid chelate) 80 mcg 178%
Sodium 570 mg 25%
Potassium (as dipotassium phosphate) 890 mg 19%
Creatine Monohydrate 3 g **
L-Glutamine 500 mg **
Inositol 250 mg **
PABA (para-aminobenzoic acid) 5 mg **
* 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 Whites, Sweet Whey), Natural And Artificial Flavor, Medium Chain Triglycerides, Lecithin, Malic Acid, Acesulfame Potassium, Sucralose, Yellow 5.

Directions For Serious Mass Weight Gainer:

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-management 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 and support muscle growth as well as contributing to a high-calorie diet.

Post-Workout: Begin drinking 1/2-1 serving of Serious Mass 30-45 minutes following exercise to support muscle growth. Before Bed: Drink 1/2-1 serving of Serious Mass about 45-60 minutes before bed to provide nutrients to help maintain 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: Do not exceed the recommended daily dose. 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). Food supplements should not be used as a substitute for a varied diet. Store in a cool, dry place.

Flavoured Ready to Mix Powder with Protein, Carbohydrates, Vitamins, and Minerals, with Sweetener.

Made in the UK

OPTIMUM NUTRITION: 4 Waterside, Kingswood Avenue, Citywest Business Campus, Dublin 24, Ireland

* 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.
Learn more about Whey Protein.
Check out other Performance Products.