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Optimum Nutrition

Optimum Nutrition Serious Mass Weight Gainer Protein Powder, Chocolate 12LB

Based on 34,927 reviews
Condition: New
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$118.78
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At a glance

Condition
New
Flavor
Chocolate
Size
12 lb (Pack of 1)
Dimensions
11.5 x 5.5 x 16 in
Weight
12 lb
Diet Type
Vegetarian
Protein Source
Whey

Features 6

  • HIGH-CALORIE MASS GAINER FOR SIZE & STRENGTH:Delivers over 1,200 calories per 2-scoop serving to support weight gain, bulking phases, and increased daily energy intake when diet alone isnt enough
  • 50G PREMIUM PROTEIN BLEND: Provides 50 grams of blended protein per serving to help support muscle repair, recovery, and lean mass development after intense training
  • HIGH-CARB ENERGY SUPPORT: Packed with over 250 grams of carbohydrates per serving to replenish glycogen stores, fuel workouts, and support sustained energy throughout the day
  • ADDED VITAMINS & MINERALS FOR DAILY NUTRITION: Includes 20+ essential vitamins and minerals, including Vitamin C and Zinc, to help support overall nutritional balance and immune system function

Description

More calories. More protein. More carbs. SERIOUS MASS by Optimum Nutrition serves over 1,200 calories, 50g of blended protein, and over 249g of carbohydrates per 2-scoop serving to help you maximize your daily caloric intake – the ideal post-workout and between meals shake for sizing up your goals. SERIOUS MASS provides you with more tools to help you pack on pounds, when taken in addition to normal calorie intake and over time with regular resistance training.

Specs 29

Product Dimensions 11.5 x 5.5 x 16 inches; 12 pounds
Item model number 1101529
Department unisex-adult
Manufacturer Glanbia Performance Nutrition
Flavor Chocolate
Diet Type Vegetarian
Product Benefits Immune Support, Muscle Growth, Weight Gain
Protein Source Whey

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Wednesday, Oct 28

This item is non-returnable:

Non-returnable due to Food safety reasons

View our full returns policy here.

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Top Amazon Reviews

Game-changer for weight gain! Helped my son put on 20 lbs of healthy mass!
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
If you or a family member struggle with a high metabolism or trouble putting on weight, Optimum Nutrition Serious Mass is the real deal. My son was having a really hard time adding weight and building mass despite eating constantly and working out. We decided to give Serious Mass a try, and it completely transformed his progress—he’s gained 20 pounds! Here is what made it work so well for us: Calorie Dense & Effective: Getting enough calories through solid food alone was a constant battle. Packing over 1,200 calories and 50g of protein per serving made it effortless for him to hit the surplus he needed to actually grow. Great Taste & Versatility: We went with the Chocolate flavor, and it tastes great mixed with milk or water. We also found it easy to blend into custom shakes with peanut butter, bananas, or oats for extra calorie customization. Easy on the Stomach: Despite being high in calories, it didn't leave him feeling overly bloated or weighed down, making it easy to drink daily alongside his normal meals. Seeing the visible gains in his physique, strength, and confidence over the past few months has been incredible. If you have an athlete, a hardgainer, or anyone trying to bulk up safely and effectively, I cannot recommend this product enough. Worth every penny! ... show more
Reviewed in the United States on August 18, 2026 by J Gray
Gained weight for the first time in all my life... (This is probably the longest review ever but oh well) ...
Flavor Name: Chocolate Size: 12 Pound (Pack of 1)
Review Image by Josepha Schmidt
I was just about making my second order and thought it would be nice to write a review. I'd never been a 'review person' and that's why even though i bought this product in 2014, i never had the time to review properly until now. I've decided to 'give back' too and not be so selfish thus, make it a habit from now. What better way to start off than with the products i've used and appreciated so much? *IF YOU DON'T WANT TO READ EVERYTHING, THIS'S JUST ABOUT MY CONCLUSION TO 1st TIME BUYERS OUT THERE* BASICALLY ; 1. Be sure to workout intensely (esp. your tummy area) to prevent belly fat (cause trust me, it is real) like the plague 2. If you find the mixture too sweet for your liking you could always dilute it with extra milk, some water, or anything other thing that works for you instead of complaining & whining about it and trying to force it down 3. Mixing the chocolate & vanilla flavor (with milk) was something i wish i'd figured out sooner. I couldn't have asked for a better taste. 4. If you're a hard gainer, you can be assured that this product WILL do something for you (if you take it properly and workout well it would do a whole lot more than that). I would know because i'm a serious hard gainer myself and wouldn't even say i 'used it that properly' at all but, in the end i did see noticeable gains and got weight gain compliments for the first time in all my life. I'm sure if you eat well, train really hard, and take this alongside you'd be just more than fine! 5. It has some kind of "very sweet after-taste" though, which lasts for some time. (could be up to 12hrs or more) even if you keep eating things in-between or after you take this. What happens is soon as your mouth becomes empty for some time you start to "feel the taste all over again". I find it very annoying lol but it's the ONLY PROBLEM I HAVE with this product. I'm ok with any other thing. 6. Remember to check with your doctor before taking this (if you have any health issues or are on medication or any other supplements). My "testimony"...(if you're interested) .. I'd never gained above 5 lbs in such a short time my entire life! I weighed 42kg (92 lbs) before i started my weight gain journey in September 2014 and by the time my serious mass got finished (i visited a hospital in January 2015), checked my weight and it said "50kg (110lbs)" I'd never gone past 45kg my entire life! Even when i received those "you've put on weight compliments" when i was younger, highest i prolly was that time was like 43kg. Because of this i thought there was a mistake in the scales they were using at the hospital two year ago. because at that time i wasn't even taking the serious mass anymore cos it had finished about a month or so ago and i'd stopped working out for about a month or so as well. I actually asked the doctor "um,are.. you really sure it's 50?..didn't it just say that because of my clothes or something?" (and i'm someone who'd never asked a doctor "are you sure" ever in my life!) ... I mean i knew i gained some weight all right while i was still 'on track' with this, but then i knew i'd 'stopped my journey' and wasn't even doing anything anymore so i had definitely lost weight again. That's why i was so surprised! I mean, i had a mirror in my house and all ok?, but i guess because i was constantly looking at myself almost every hour on my gain journey i never actually realised that i had gained! It really was 50kg. I had gained 7kg in 2 months!😇 (A HARD-GAINER) i want to stress on that again. LOL I found it really hard to believe so i had to check again during that week with a different scale (for some weird reason i didn't have a scale at home and always had to check outside of the house) lol i really wasn't serious. I checked and got the same measurement to my uttermost surprise. I didn't believe it (still) ... but then after some time i finally got over it & accepted it. That was when it hit me... "Oh, wow..does this mean i gained even more while i was still on the serious mass?" .."umm.. Huh? " And then it hit me again... "this is the first time i've reached 110lbs! ...omg..*my eyes filled with tears* About a year ago that was actually my dream.. to get to 110lbs, and now i'm here! What is this?? How did this even happen?" Well yeah, i WAS extremely confused for a long time. Trust me on that one. WELL ABOUT WORKOUTs; I used to do normal 'home exercises' and i never even went to the gym. I had a workout routine, but because i'm severely anaemic it was always extremely difficult for me to workout properly (and the way i REALLY wanted to). So i did basically some 'soft workouts'. I didn't have dumbbells at the time, so all i did was basically "no dumbbell home exercises" or "workouts without weight" more like it. This is why i was so surprised i gained. I realised that if i'd used weights i would've gained even more. I did squats mainly, (different types of squats) and then some donkey kicks and tummy workouts usually. I normally followed "fitnessblender" videos on youtube, and then some other fitnessmodels' videos that i found. *****I bought 2 chocolates 1 vanilla the first time i ordered this product (yes, it was a huge risk i took but this is just how much i believed in this product even before i tried it for myself). I fell in love with it and knew right from the times i researched about it that it was the RIGHT one for me. That was what i needed tbh, and i just knew. I don't know how but oh well, it did pay off in the end so i guess i was just very lucky***** I never really experienced any form of 'super strength' or felt 'so strong' to do my workouts or anything whenever i used this DURING workout, (and i would not blame it on this because i already had serious low energy problems from my anemic condition), and plus it even says to use it mainly as "between meals, post-workout & before bed" in the description (which i did, but also used it as a pre- and during-workout shake as well) so um, because of that i'm not gonna say it didn't do much or help me with my workouts at all. I used it as a pre-and during workout shake mainly because it had creatine and i thought it would help me workout better and easier (But maybe i didn't experience that much of a change in strength/performance because the creatine content is really small? idk) but then i do know it helped me in all sorts of other ways nonetheless. I RECOVERED FROM MY WORKOUTS REALLY FAST and that was an incredible one. FOR THE TASTES; THE CHOCOLATE; wasn't bad at all when mixed with milk. I used non-fat milk as they recommend, but then always added some extra cup or so of full cream milk after i got my serving (to dilute it a bit). This was good, i liked better the taste it gave me when i did that, but then the downside was that it increased the amount of the shake and so was always a bit harder to push down quickly. THE VANILLA; wasn't bad either. I actually grew more fond of that after sometime when i'd taken the 2 chocolate bags for so long. I liked the taste of that too, but again, it was also way too sweet for my liking when mixed with milk (esp the after-taste). so i'd always add some extra full cream milk/a little water to it to dilute that a bit as well after i'd reached the serving size. After a while, i started mixing both flavors together and IT WAS GOOD! (i only had a few cups of the chocolate left when i figured this out, so i couldn't do that for long, but then with the few days i did that, i never regretted)! I would take one cup of the chocolate flavor, one cup of the vanilla flavor, blend them together, adjust a little with some extra milk, and i'm all good! (I always said to myself "why didn't i think of this earlier?!" lol) In general i never tried any with just water but my brother did once and from the look of things, it's clear they both taste better with milk. I never tried mixing either with other solid stuff like peanut butter, oats & the like because i mostly used to blend them with other liquid nutrition shakes (and they always blended well) but i'll try mixing them with dry oats and some other solid stuff this time and see. I'll be sure to leave an update later! Anyway, to continue my "testimony"; In the beginning i couldn't eat any solid food the rest of the day after i took this in the morning. It filled me up more than a 3 square-meal ever would have so i was always worried i was going to end up relying on that and use that as my 'sole source of nutrition' the entire time. Good thing was.. after a while it SERIOUSLY 'OPENED UP MY STOMACH'' and i was able to eat more than i ever could have handled on my own usually. That made me very happy indeed I knew it was the work of the serious mass because that was by far the most caloric supplement i was taking. The other products i took alongside (more for medical conditions & clinical purposes)were ; Scandishake vanilla -580 calories Enshake chocolate- 600 calories (That was probably why i gained so much but i know the serious mass contributed greatly too!) Oh and, ABOUT THE BLOATING THING PEOPLE SAY.. What i'm gonna say is it is really true. And i realised it when i experienced it myself. (I already believed and was aware from what i'd read even before i bought the items, but i guess i just didn't think it would be that serious!) lol Yeah, the bloating is SERIOUS as well. I had read that you have to workout insanely if you didn't want to end up putting on ONLY FAT so i was already prepared for that. *Only i wasn't as prepared as i thought i was* lol But then to be honest.. with all my 'daily ab workouts' and the like.. i still did have a big tummy while on this mass gainer! lol I probably didn't workout as hard but all i know is i gained weight in the places where i wanted to gain all right, only it came with a lot of belly fat too! I didn't even care at the time though, cause at the time i was far too happy with the gains and knew i could workout later to reduce the belly fat. It was only funny because i'd always been a skinny girl, and i'd never seen my tummy so big (i was actually afraid at some point that it was going to stay that way and it would never go back to the way it was! lol). I mostly felt 'bloated' and i think it's because i wasn't used to having so much calories in my body. I felt so 'heavy' and 'so pregnant' all the time because i was always so full! lol it was a struggle. But i managed to pull through it. After some time of going off my weight gain journey i got my flat tummy back! :) I know what to do this time if i started my journey again so i doubt that would happen anymore! I will train harder than i did last time so i'm very well prepared i must say. So should you! 😊 I would say it was fun though! The whole experience was fun and exciting as i'd never had that much CHALLENGE thrown at... well my body..ever! I was new to working out and all these mass gainers and the like. I gradually grew from there over time.. and now i know so much more than i didn't (two years ago) about mass gainers, workout routines and the like. I'm still attached to serious mass (yes of course, the love is still there!) and i would keep on buying until i've reached the goal i've always wanted to reach. (which is around 60kg or 132 lbs. I weigh 40kg now, that's about 88lbs yeah, unfortunately.. i lost all that weight in the course of just 1 year and i'm 21 now (which means very much underweight since i'm only 5'3) which is why i'm getting myself more bags of this product)! Funny thing's, i'm not even in the United States or Canada or the UK. I'm not in a country where i could easily get this product when and if i want. But then i still manage, and do all i can to get it every time (If i told you how much trouble i go through and how much money it costs me every time, you would marvel!) The number of things i could buy with the amount i spend just trying to get 2 bags of serious mass down to where i am... it's ridiculous but oh well, when something's worth it you're never really bothered so this should tell you just how much useful this product is! Those of you who can just order it and get it the next day or two (and at this price with no other extra costs), be very lucky and make good use of it. (I'm not getting anything for this review just so you know, i do not know the company or haven't had any agreements to do this with whatsoever. I took time & wrote this review wholeheartedly just so future buyers would know what a great product this is just in case they were having any doubts) 😊 For hard gainers... i'll DEFINITELY recommend! ... show more
Reviewed in the United States on February 18, 2016 by Josepha Schmidt
Muscle gain
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
“I really love this protein because I’m seeing my body earning muscles and the taste is fantastic.
Reviewed in the United States on July 24, 2026 by Cristian Charles
Good product 😍
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
Trying this protein powder and loving it so far💪 Easy to mix, great taste, and a perfect addition to my daily routine. Can’t wait to share my honest results
Reviewed in the United States on August 2, 2026 by Lancia Ciril
Good Stuff!
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
Amazing!! After losing 25lbs from an illness, this stuff came in clutch. I’ve been having trouble getting my appetite back, so I started drinking the shakes 2-3 times a day to supplement what I do eat. I’m up 10lbs. The taste is pretty good too. It’s not gritty or chalky either. I really like the chocolate. I mix it with ice and milk. Enjoy 😊 ... show more
Reviewed in the United States on July 31, 2026 by Amazon Customer
Price gouge
Flavor Name: Chocolate Size: 12 Pound (Pack of 1)
The product is fantastic, I’ve been buying this for years. The issue I have is that I used to pay half of what the cost is now. I paid maybe $55.00 for it only 5 years ago…same product, same amount (12lb bag). The fact that it has double in price is unfathomable.
Reviewed in the United States on August 31, 2026 by Alex West
You will gain weight and have more energy.
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
This really works. I had cancer surgery on my mouth and lost 20 pounds. I couldn’t eat my favorite foods. But love chocolate shakes. My son bought this while he was weight lifting and advised me to try it. He bought it for me and I made a chocolate shakes. It is delicious and I gained 5 pounds the first month and have more energy. I’m able to do my daily chores 😁 ... show more
Reviewed in the United States on August 17, 2026 by Amazon Customer
What They Don't Tell You
Flavor Name: Chocolate Size: 6 Pound (Pack of 1)
Review Image by Tera R
What they tell you. It tastes great and is a good supplement to build mass. What they don't tell you. Each serving consist of 2 huge heaping scoops of powder and 24 ounces of fluid (water or milk). This combination results in 48 ounces of liquid delight that they claim is a single serving. On what planet is 48 ounces a single serving? To put this in perspective, that is 2 full to the brim Shaker bottles that are intended to be consumed as one serving. 340 grams of powder from one serving translates into 3/4 of a pound of powder. Again to put this into perspective, the huge tub of powder you will recieve equals ONLY 8 advertised servings. The other thing they don't tell you is the powder is so fine and gummy that the only way to prepare the drink is to use a full sized blender. No Shaker bottles here. Preparing this mix is a mess. The powder is so fine that it creates a gummy mess that adheres to the side of the blender like Venom on Eddie Brock. Prepare to spend a significant amount of time coaxing the paste free to get it to properly mix. Great protein mix, but I sometimes I feel like it would be easier to eat 5 chicken breasts too reach the same calorie goal, than to put down 48 ounces. I realize that it can be broken up throughout the day, but so can multiple meals. There is also the option of using another protein supplement with a realistic serving size, multiple times a day. In the end, I feel like that is all they have done with this product. They have combined a multiple dose, throughout the day protein powder into a single serving, trying to advertise it as a solution that they obviously have not solved. ... show more
Reviewed in the United States on December 9, 2023 by Tera R
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