Optimum Nutrition – Serious Mass (12lbs)

Optimum Nutrition – Serious Mass (12lbs)

A black and green bag of ON Optimum Nutrition Serious MASS calorie rich protein source with 1250 calories

Optimum Nutrition – Serious Mass (12lbs)

$99.99 $79.99

In stock

$99.99 $79.99


  • Adding Calories Has Never Been This Easy or Tasted So Good
  • 1,250 Calories
  • 50 Grams of Blended Protein
  • Over 250 Grams of Carbohydrates with NO ADDED SUGAR
  • Creatine, Glutamine and Glutamic Acid
  • 25 Vitamins and Essential Minerals




Serious Mass is the ultimate in weight gain formulas. With 1,250 calories per serving and 50 grams of protein for muscle recovery support, this instantized powder makes the ideal post-workout and between meals shake for sizing up your goals. Serious Mass provides you with the tools you need to pack on the pounds and help you develop the physique you’ve always wanted.


Optimum Nutrition

ON Optimum Nutrition logo ON black italic font with arrow through the letters

Additional information


Chocolate, Strawberry, Vanilla


  1. 5 out of 5

    Craig B (verified owner)

    My favorite brand!

  2. 5 out of 5

    Isabella Yates (verified owner)

    This stuff is great!! The chocolate taste is amazing just like a milkshake from an ice cream parlor. I don’t get why some people don’t like the taste because I am really picky about flavor and mixing this with milk makes it just like a store bought milk shake! Well 2 weeks now and I gained 3 pounds! Love this product!!Buy it now!!! Buy Another!!!

  3. 5 out of 5

    Patrick Wilkerson (verified owner)

    Man, I’ve gained tons of weight! This beats eating at McDonalds every day to gain weight.

  4. 5 out of 5

    Chris Lucas (verified owner)

    I’ve been struggling with weight gain for the longest, but this thing is helping with the cals that I need in order for me to reach my goal.

  5. 5 out of 5

    Craig Harvey (verified owner)

    Fast shipping

  6. 5 out of 5

    Delia G (verified owner)

    Optimum Nutrition is the best!

  7. 5 out of 5

    wesley p (verified owner)

    Way better price than where I usually shop from

  8. 5 out of 5

    Joe G. (verified owner)

    good flavor, used as a meal replacement for chronic illness which prevent ability to digest food at times

  9. 5 out of 5

    Dominic Hogan (verified owner)

    I got this to add extra calories to my daily intake because I want to gain weight. This is the best tasting protein powder I’ve gotten so far. It tastes just like vanilla, and i mix it with lactaid and i don’t have any stomach aches after as i have had in the past with other brands. I’ve already started gaining weight and it makes me feel full until I am able to have a full meal. I love it! I plan to buy again and buy double next time!

  10. 5 out of 5

    Harriet K. (verified owner)

    I gained 10kg after using this mass gainer in just 6 months. It has a very good taste and high calories and protein count. I would certainly recommend this to anyone who is looking to gain mass.

  11. 5 out of 5

    Georgia O. (verified owner)

    Good ratio of protein to carbohydrates for hard workouts! Great taste and mixes well! I mainly use it as a pre-workout drink…1/5 serving about 30 minutes prior to exercising. It is a great post workout drink as well. I’d recommend drinking it within 30 minutes of finishing your routine. If I drink it afterwards, I use 1/2 serving. I plan to purchase again soon!

  12. 5 out of 5

    Hunter J (verified owner)

    I’ve tried a lot of different protein powders and have been disappointed. I don’t like the taste of most of them. This one (chocolate flavor) is delicious. I blend 2 scoops with some almond milk, bananas, peanut butter and some ice cubes and it is SO delicious. It’s very filling. Definitely recommend it!

  13. 5 out of 5

    iva m (verified owner)

    Thanks supplements direct!

  14. 5 out of 5

    Augusta Estrada (verified owner)

    I’ve been using the serious mass protein power for about as long as I’ve been working out. I’ve tried the vanilla and the chocolate flavors. I’m not sure if there are other flavors but the vanilla and the chocolate are great. Personal, my favorite one is the vanilla. Every time I order it, it always come on time. The package is always neat. This protein powder works, but you have to put works in the gym too, otherwise, you won’t see any results.

  15. 5 out of 5

    Myra Saunders (verified owner)

    if you can hold three or four of these shakes at half recommended dosage a day along with increased dietary intake and heavy physical / workout regime for four months, get ready to put on 40+ pounds of pure muscle – watched my 25 year old firefighter son go from 123 lbs to 169 lbs in that length of time – just one anecdotal example, not a medical promise…

  16. 5 out of 5

    Hannah D (verified owner)

    I don’t ever use the full 2 scoop recommendation but i’m a skinny guy and for gaining mass this stuff is amazing. This is my 3rd bag and I will keep ordering it. I actually just started a subscription! You won’t be disappointed!

  17. 5 out of 5

    Harold Flowers (verified owner)

    I love love love this!!!My boyfriend gained weight (mostly muscle).His arms got big and all 😉 He is very pleased with this product…Will continue to order this!!!

  18. 5 out of 5

    Adeline N. (verified owner)

    Awesome for gaining weight! It’s always been my struggle. I would drink this before bed so I wouldn’t burn the calories as fast while sleeping and it was very effective with helping me gain weight. I was a 22 year old girl 5’9 and only weighed 105 lbs last year, very underweight! Drinking these chocolate shakes at night plus milk, plus peanut butter I gained 15 pounds fast!! Almost at 130 lbs. now 🙂

  19. 5 out of 5

    Jay Palmer (verified owner)

    I have used this brand for over a year now. I love it’s pureness, ingredients, and micronization. On cycle I can get about 10 pounds in a month added with proper diet and exercise.

  20. 5 out of 5

    Lucile B. (verified owner)

    Works great! I used to use gainers fuel 1000 way back when and I looked for a suitable weight gain replacement. I don’t eat much throughout the day and taking this in the morning helps keep my weight steady. I would like to add it’s important to use this with a workout regiment .

  21. 5 out of 5

    Hunter K. (verified owner)

    Love this gainer. As someone who weighs a little more then 100 pounds I needed this to reach my macros and it’s hard to get them in with food alone. You have to be working out or else you’ll just gain fat and no muscle form. The taste is something I hate. I currently only take one scoop a day but i separate it into two shakes with half a scoop each. I mix it in with a cup of frozen strawberries and a banana and it makes it a little bit more bearable. If you still can’t bear it , eat a mandarin on the side after each sip, it made it taste kinda like yogurt to me. Will make a YouTube video about it soon.

  22. 5 out of 5

    Ellen Collins (verified owner)

    It does what it says it does, i was able to gain 20 lbs supplementing with this. It can be intense at the beginning but its all about finding the right balance, never do a full dose at once. Just do 2 half doses theoughout the day, sometimes i just do half a dose in one day since it is so heavy. I started out w vanilla, but i now prefer the chocolate flavors much better, a lot easier to go down, i like to add banana and peanut butter to it.

  23. 5 out of 5

    Claudia M. (verified owner)

    Before trying this product, chocolate, I tried the peanut butter chocolate and comparing the two – chocolate peanut butter is way better, chocolate left a bitter aftertaste.

  24. 5 out of 5

    Edgar O. (verified owner)

    This is the best purchase I believe I’ve bought so far. This thing is huge. The calorie that it provides along with all the nutrients is ideal for what I need it for. I have a hard time gaining weight and this seems to be helping in the process. The taste is not bad, at all.

  25. 5 out of 5

    Delia R (verified owner)

    I recently had a health problem that caused me to lose a dangerous amount of weight. This mass gainer has been absolutely amazing with helping me to get my weight crawling back up just a bit faster than normal. The chocolate flavor was a great surprise, really tasting like chocolate! When I added that with a drop of chocolate syrup and a tablespoon of peanut butter in milk, it tasted like those peanut butter M&Ms. Everyone has different needs for mass gainer, so this was a great surprise for me!

  26. 5 out of 5

    Jane Lucas (verified owner)

    Supplements Direct is the way to go

  27. 5 out of 5

    Ruby Roy (verified owner)

    I LOVE this mass gainer! I purchased it in hopes to start gaining more muscle mass and it did just the trick, I would take Half a serving 2-3 times a day! It is tasty ( shake well to get the kinks out lol) I typically would drink this with milk, the chocolate flavor tasted really great! In comparison to another mass gainer I tried (chocolate flavor) this had the same amount of calories and tasted much much better than the other brand I tried, will absolutely stick with this one

  28. 5 out of 5

    jessie g (verified owner)

    Quick shipping to Calgary! Thanks SD!

  29. 5 out of 5

    Carrie P. (verified owner)

    Mmmmm, Chocolate, mixed with water and milk, very very tasty, easy to drink, 5 out of 5, will buy again for sure hella good!

  30. 5 out of 5

    Delia C (verified owner)

    Been purchasing this product for quite a while now. Gains have been made using this product and will continue ordering it. The tastes are actually pretty good and mixes well. The only clumps I get is when it bunches up near the spout. If you split the servings however it does not happen as much since the scoop size is almost equivalent to a garden shovel. All and all its a great product, and offers a lot more than the standard protein powders.

  31. 5 out of 5

    austin b (verified owner)

    I definitely love this protein powder. The way I gained weight happened really fast, about 40 pounds in 2 months and this product helped tremendously. I have to say I hated the vanilla flavor though lol. But I loved the chocolate! Remember to work out as well because otherwise you’ll start getting fat around your stomach which is what happened to me.

  32. 5 out of 5

    Matilda F. (verified owner)

    I was a skinny guy at 140 pounds and had to eat 3000 calories a day to gain weight.. Never could keep on the weight. Started drinking this 2-3 times a day. Now I’m 170, and built great muscle mass. If you’re a skinny guy like me and wanna build muscle this is the way to go.

  33. 5 out of 5

    Maria C (verified owner)

    Literally helping me gain weight. I used only 1 scoop a day and don’t have time to eat much and still managed to gain 3 pounds in a week. I also don’t work out.

  34. 5 out of 5

    Mable F. (verified owner)

    I haven’t used this long enough to chart any significant progress — but I can attest to how great it actually it tastes! I HATE the taste 99.9% of powders! No matter what, I have not been able to get past that artificially foul and chalky taste. But as a previous poster had mentioned, it does taste like a Wendy’s Frosty. Okay, maybe not that great — but better than the rest!

  35. 5 out of 5

    Augusta P (verified owner)

    Awesome customer service, fast shipping, great product

  36. 5 out of 5

    Roy D (verified owner)

    Needed a supplement to get me through head & neck radiation treatments when I could no longer eat solid foods. Made high calorie smoothies out of it. Very good flavor. Did both vanilla & chocolate but preferred vanilla because it gave more flexibility with flavors (added flavored yogurt and chocolate syrup to give me options on taste). Very good flavor. Tried another brand from a local nutrition store. This was much better tasting. Helped me to keep my weight on..

  37. 5 out of 5

    Sophia C (verified owner)

    I’ve gotten thicker than a snicker. So much mass. And it tastes WONDERFUL. I almost feel like I’m cheating. It’s great. I’m on my third tub

  38. 5 out of 5

    Lloyd R (verified owner)

    In 5 weeks I went from 103lbs to 115lbs (I’m 5’1) all I have been doing is weight training and making sure I’m eating in a surplus and drinking my protien shakes post workout. I will say it was making me super bloated so I cut it to just 1 scoop I add half a banana, 1 scoop of peanut butter, and a splash of vanilla almond milk. The taste is absolutely amazing. Will be buying more.

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