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Optimum Nutrition

Optimum Nutrition Serious Mass Weight Gainer Protein Powder, Strawberry 6LB

Based on 9,758 reviews
Condition: New
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$77.97
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At a glance

Condition
New
Flavor
Strawberry
Size
6 lb (Pack of 1)
Dimensions
8 x 8 x 10.12 in
Weight
2.73 kg
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 8 x 8 x 10.12 inches; 6.02 pounds
Item model number 1031919
Department unisex-adult
Manufacturer Optimum Nutrition - NutWell
Flavor Strawberry
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: Sunday, Nov 1

This item is non-returnable:

Non-returnable due to Food safety reasons

View our full returns policy here.

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Similar Products

Top Amazon Reviews

Seeing good gains from a good daily workout - been taking for about 6 months
Flavor Name: Strawberry Size: 12 Pound (Pack of 1)
Review Image by Tyler Wayne
if you put in the work from exercising enough you will get what you put in and this ON serious mass supplement will help you a lot on gains. It is great for a workout supplement, i have been taking this product for about 6 months and have seen great results. i havent had any issues other than high triglycerides recently but that is non related to this product as my dad said he use to have high cholesterol years ago too so that's just hereditary for me. I usually take 1 or 2 servings per day with water but you can take more or less depending on your daily diet needs and it says on the package you will get more calories if you mix it with milk as well as having some recipes to add certain foods or drink to mix things up. everyone is impressed with my gains and have been getting compliments from many people on how buff i look compared to last year. i dont take any other supplements to help with gains i only take Optimum Nutrition serious mass and i have been working out almost everyday with taking some rest days once a week or so maybe. you also have to make sure you eat regularly in your daily diet to ensure you will be in a surplus and getting your daily food sustenance for your body to digest. i would recommend this product to any of my friends interested in working out or trying to put on some muscle. strawberry and vanilla flavor are my favs i dont think i have had chocolate yet or the others. one scoop of serious mass is 1/2 serving so if you have a regular bottle that you use to mix it with youll only be able to fit about 1/2 serving, i tried putting 2 scoops in once with a average bottle and there wasnt enough room to put water in. I usually take it right after i get done with my workout sessions during the day or in between meals and sometimes before bed. not only have I seen gains in muscles but it also helps give you more energy during the days when taken regularly and doesnt have a crash like with high energy drinks. like i said though if you dont put in the time to do your workouts you will probably just get fat. A 12 pound bag will usually last me about 3 weeks of 1 or 2 servings per day or so, so you will need to order about once a month or so to keep stocked up and this is the best deal i have found yet. thank you Optimum Nutrition for making this product it has helped me a lot with my fitness journey! - Tyler ... show more
Reviewed in the United States on May 17, 2019 by Tyler Wayne
Best protein shakes ever
Flavor Name: Strawberry Size: 12 Pound (Pack of 1)
Review Image by Nosiest
Not only is this an Amazon a quality amount of protein, but it tastes so good! Usually, protein shakes taste worst than anything else but the STRAWBERRY flavor is fantastic (all other flavors like chocolate and peanut butter are absolute dog poop) you cannot go wrong with strawberry. At first, if you’re first starting to work out, you might have some stomach issues, but you have to very slowly increase the amount and your body will get used to it. I ONLY use one scoop because two is ridiculously too much and I don’t want to end up with liver or kidney failure lol but one scoop is good. Once you get used to it, no stomach issues at all! Very effective, I have gotten so many compliments from others who have been at the gym for longer and ache for my results. You must remain consistent with the gym and workouts, do very intense workouts. If you don’t, then you’ll just get fat from this lol I advise to only use one scoop size to make the bag last longer and prevent any health issues, two scoops is ridiculously too much. Be consistent and you can play with some mix ability and throw banana or some other fruits if you want. I would recommend and will continue to buy this after so many years of already doing so ... show more
Reviewed in the United States on January 18, 2026 by Nosiest
It helps a lot
Flavor Name: Strawberry Size: 12 Pound (Pack of 1)
Optimum Nutrition Serious Mass is a great choice for anyone looking to gain weight, build muscle, or increase overall calorie intake. The Chocolate flavor mixes smoothly—especially if you use a blender—and has a rich, dessert-like taste without being overly sweet. Each serving delivers a very high amount of calories, protein, and carbs, which makes it ideal for people with fast metabolisms or those who struggle to eat enough throughout the day. It also includes added vitamins, minerals, and creatine for extra support. The bag is large and lasts a good amount of time depending on how much you use. The powder is heavy, so mixing by hand can be a bit difficult, but blending solves that problem easily. Overall, Serious Mass is effective for healthy weight gain and muscle-building goals. If you need a calorie boost and don’t mind a thick shake, it’s a solid and reliable product. ... show more
Reviewed in the United States on December 7, 2025 by Kamila Chirinos
I did gain
Flavor Name: Strawberry Size: 12 Pound (Pack of 1)
First of all I tried the vanilla and the chocolate flavor. Please do yourself a favor and only get the chocolate flavor. Listen, the chocolate flavor is the same in every other brand protein shake or mass gainer because they all use cocoa powder. So if you like chocolate you will not be surprise when you taste it. Compared to the vanilla one which has a very unique taste that I did not like. Just get the chocolate one. Also, the servings say two scoops but if you have not seen the scoop it is the same size as a detergent scoop. It is even hard to take it out of the bottle. One scoop is enough for one serving (625 calories). If you do decide to take two scoops space them out throughout the day. I do not recommend this though since you should be getting the rest of your calories and nutrients from real food. One scoop every day is fine though. Ok, so how did I mix it? I used a electrical blender. I have used a shaker bottle with the metal spring ball thing before since I did not have a electrical blender in my college dorm. But it taste much better if you blend it with an electrical blender because you will not have large clumps. Also, you can add other ingredients if you like such as peanut butter (chocolate flavor + pb taste freaking good just like reeses cup). Peanut butter adds more calories and protein to your shake. Do not take this mass gainer if you are not working out at least 3 times a week. You will simply gain a gut around your stomach area unless you are anorexic. Even if you are anorexic, you should still work out. And if you are like me and are still looking to add calories to your serving, add in 1 tablespoon of olive oil (120 calories), and you will not taste as long as you drink fast enough so the olive oil does not float up after you blend it. So my shake usually is 1 scoop (625 calories, 24g protein), 12fl oz of milk (225 calories, 12g protein), 2 tbsp of peanut butter (190 calories, 7g protein), 1 tbsp of olive oil (120 calories). Total of 1160 calories, 43g of protein (hopefully my math is correct). With all of that being said, I recommend to buy Optimum Nutrition 100% Whey Protein (Extreme Milk Chocolate flavor) instead of serious mass because this gainer has a ton of carbs. The first ingredient is Maltodextrin which is normally found in soda and candy. You save a lot of money also since the whey one has more servings. Last advice, use MyFitnessPal app if you have trouble gaining weight. Make sure you are actually hitting your calories goal. I used to think that I had a fast metabolism because I ate so much. But in reality after I calculated the calories, I was far away from hitting 3000 calories. I gave it 5 stars because it worked for me. I went from 145lbs to 160lbs in three months. Yes I gained fat but also muscle because I worked out. I no longer take this after finding ON 100% Whey. Much cheaper per serving, a better selection of flavors, and a lot less carbs. Yes, it might not have the calories but you can definitely create your own mass protein shake by using the correct ingredients. Google svunt shake if you need an idea of creating your mass gainer with whey protein (it has 1659 calories and 95g of protein). Have fun gaining. ... show more
Reviewed in the United States on January 4, 2024 by Heidi walls
Works Great but...
Flavor Name: Strawberry Size: 12 Pound (Pack of 1)
Review Image by Josiah Industries.
Review Image by Josiah Industries.
Review Image by Josiah Industries.
6'2 150 pounds unhappy with my body wanting to gain body weight, muscle and strength 12/5/19 I did and to this day eat 6 meals a day: breakfast, snack, lunch, snack, supper, snack. then bed. this in the past was not even enough to gain the kind of weight, and muscle i was looking for. and believe me i was not skimpy on servings. And researched my diet extensively...i am not going to bore you with the normal Eggs oatmeal rice nut (haha) green stuff...extra.. But as any extreme diet program that i had cooked up for myself the endless Cooking, packaging, taking food to work eating every 10min break and obviously lunch time began to get exhaustive and i found myself cheating or just skiping eating "sessions" which gets expensive and is annoying and discouraging... also eating and trying to gain weight when you are under weight is hard! just eating enough is a mental battle in itself. I ordered my first bag of Serious Mass in January 2020 i initially daunted by the huge doses required i decided take half sevings (one scoop) and to stick with my regular eating habits but integrate the Serious Mass into between meals. i also slightly dial back the amount I was eating for snacks. (like a handful of almonds or some peanut butter) Well i can tell you this stuff works great I noticed a huge difference in my hunger levels and in the amount of muscle I was gaining and weight. 4/9/20 as of today i weigh 190lbs and am still lean. great product. i take only half scoops whole is to much for me. My meal plan now: Breakfast, Serious Mass, Snack, Lunch, Snack, (Workout after work) Supper, Serious Mass, Snack, (Bed) Using this product sparingly even has greatly increaseed my results and weight gain i am very happy. Now a few tips.( i have bought 5 bags) Flavors: Chocolate. heavy not good for morningsbut good. Banana. very sweet but light and good for morning. Strawberry. mix of both (i got tired of it tho) Mixing: Do yourself a favor and get a 32 oz + shaker cup two heaping scoops is one serving will almost not fit in a 32 oz shaker cup dry! so take it in half servings and space it out. Also do not put the Shaker ball in first it will be a dough ball. put your Serious Mass in your shaker cup add milk or water shake it up. there will be some clumps so then add the shaker ball in and shake again. this will give you the best consistency. This stuff tastes like cake mix and can be hard to drink( just kinda thick) If you use water it will make it so much easier to drink after working out especially. (In the picture is 2 scoops on a small plate to give you an idea of the amount) Over all great product! VERY happy with it! ... show more
Reviewed in the United States on May 10, 2020 by Josiah Industries.
Okay
Flavor Name: Strawberry Size: 6 Pound (Pack of 1)
Just didn’t like the taste🤷
Reviewed in the United States on July 24, 2026 by Shawn
Mixes well and tastes strong
Flavor Name: Strawberry Size: 6 Pound (Pack of 1)
Good powder mixes well with milk and water. The flavor is pretty strong, I got strawberry flavor and no matter how much chocolate vanilla or other flavors strawberry is all I tastes so I recommend getting a flavor you really like. I’ve had other protein powders and mass gainers that clump up at the bottom of my shaker and this one mixes in very well with a few shakes and some ice to stir it up. ... show more
Reviewed in the United States on July 28, 2026 by Christian Siewert
Great results
Flavor Name: Strawberry Size: 12 Pound (Pack of 1)
Great results
Reviewed in the United States on August 16, 2026 by JC is the answer
How it works
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