If you’re looking to pack on some extra muscle or weight, the best mass gainer supplements can be helpful tools when trying to consume extra calories throughout the day. Multiple weight gainer options line the shelves of your go-to supplements retailer, but we feel Optimum Nutrition Serious Mass is a worthwhile pick thanks to an impressive macro breakdown that’s rich with carbs and protein but isn’t overloaded with excessive saturated fats.
In the grand scheme of things, we feel ON Serious Mass can be a great pick for budget-minded athletes since the calories-to-cost ratio is one of the best we’ve found in testing over 10 different mass gainers and over 100 different protein powders. We’ll examine that ratio along with other key qualities such as solubility, independent testing results, and (of course) taste in this Optimum Nutrition Serious Mass review. For more information on how we test supplements for our content, be sure to read our BarBend supplement testing methodology page.
This mass gainer contains 1,250 calories per serving, 100 percent of the recommended daily intake of most vitamins and minerals, and 50 percent of your daily vitamin D, which is important for testosterone.
Medical disclaimer: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. It’s always a good idea to talk to your doctor before beginning a new fitness, nutritional, and/or supplement routine. Individual needs for vitamins and minerals will vary.
Main Takeaways
- The 340 grams of powder and suggested 24 fluid ounces of liquid per serving may overwhelm your shaker bottle — we recommend mixing Serious Mass with a countertop blender.
- This mass gainer supplement includes 5 grams of creatine monohydrate, which can be beneficial for athletes looking to support muscle growth in addition to their weight gain. (1)
- Per our tester, the flavors are inviting yet not overwhelming and can mix easily in fruit-filled smoothies.
Optimum Nutrition Serious Mass Specs
| Price Per Serving | Starting at $5.25 |
| Serving Size | 340g (≅2 scoops) |
| Calories Per Serving | 1,250-1,260 |
| Protein Per Serving | 50g |
| Carbohydrates Per Serving | 251-253g |
| Fat Per Serving | 5-6g |
| Available Flavors | Banana, Chocolate, Chocolate Peanut Butter, Strawberry, Vanilla |
| Third-Party Testing | None |
Optimum Nutrition Serious Mass is available in four-, six-, and 16-serving containers, which equates to up to 12 pounds of powder with prices starting at $5.25 per dosage. This is a smaller serving size than you’ll find in many of the best protein powders, which typically offer 30-serving tubs, as each full serving calls for 340 grams of product (or roughly two scoops). As such, it may be best to mix Serious Mass with a countertop blender as opposed to a shaker bottle.
Looking deeper into the formulation, this weight gain supplement features between 1,250 and 1,260 calories per serving, depending on your flavor of choice. This means that for every dollar spent on this supplement, you’re receiving roughly 238 calories. Other mass gainers typically feature a calorie-to-cost ratio between 135:1 and 215:1.
Additionally, you can expect 50 grams of protein, between 251 and 253 grams of carbs, and up to 6 grams of total fat. “The low fat counts are surprising and I really appreciate how there are minimal saturated fats in this formulation,” notes Chelsea Rae Bourgeois, registered dietitian nutritionist and our expert reviewer. “Traditionally, mass gainer supplements will add in these unhealthy fats in order to inflate calorie counts.”
Other nutrient callouts for this powder include 5 grams of creatine monohydrate, 35 grams of amino acids (11 grams of BCAAs and 24 grams of essential amino acids), and 8 grams of glutamine. Bourgeois commends the inclusion of creatine monohydrate, specifically, as it allows athletes to fuel muscle growth in addition to the weight gain with this supplement. (1)
The primary ingredients in Serious Mass include maltodextrin and whey protein concentrate, as well as natural and artificial flavors, emulsifiers, and additional sweeteners. Maltodextrin, a common polysaccharide used as a filler agent in processed foods, is what gives Serious Mass its high carbohydrates count, though studies note that some athletes may experience GI distress as a result of consumption. (2) Be sure to take your personal sensitivities into question before opting for this weight gain supplement.
Speaking of sensitivities, while this high-calorie formulation can be excellent for hard gainers that struggle to put on weight, it’s not the ideal protein for every fitness goal. “When looking for a protein powder, ask yourself what goals you are trying to achieve, what health conditions you may need to consider, and how you’d like to use this protein powder in your routine,” Samina Qureshi, RD, tells BarBend. For example, if you’re interested in shedding a few pounds rather than accumulating mass, the best protein powders for weight loss may be a better option.
Finally, Optimum Nutrition’s Serious Mass is available in five flavor options — Banana, Chocolate, Chocolate Peanut Butter, Strawberry, and Vanilla. While this flavor roster is miniscule compared to Optimum Nutrition Gold Standard Whey Protein, which offers 22 different flavor options, there’s still enough variety to help defend against any flavor fatigue.
Who Should Use / Who Shouldn’t Use Optimum Nutrition Serious Mass
Every athlete’s needs are different and determining which supplements can support your fitness goals is a big part of developing your nutrition regimen. Below are a few camps we feel could benefit from adding Optimum Nutrition Serious Mass to their routine along with some groups that may fare better with a different protein powder or one of the best meal replacements.
Recommended for:
- Athletes looking to increase their calorie intake to support muscle and weight gain
- Individuals wanting a mass gainer supplement with included creatine monohydrate
- Hard gainers who struggle to consume optimal calories from whole foods alone
Not Recommended for:
- Carb-conscious athletes looking for protein shakes with carb counts below 250 grams
- Athletes that don’t own a countertop blender
- Individuals focused on lowering caloric intake rather than increasing their daily consumption
Our Experience Using Optimum Nutrition Serious Mass
We’ve been hands-on with tons of protein supplements over the years, including over 10 mass gainers and over 100 protein powders. In testing Optimum Nutrition Serious Mass, we evaluated its performance across multiple categories, including taste, solubility, price per serving, and more. We then rated these findings on a scale of 1 (lowest) to 5 (highest). In addition to our real-world testing notes, we also worked with an independently accredited lab to assess Serious Mass’ purity and label accuracy. Now, let’s get down to the nitty gritty with this popular mass gainer.
Ingredients and Formulation
The composition of this Optimum Nutrition supplement is pretty simple. Its main ingredients are maltodextrin, whey protein concentrate, and a handful of natural and artificial flavors, emulsifiers, and sweeteners. Additionally, there are no proprietary blends that could hide dosages of key ingredients.
We rate this formulation at 4 out of 5, too, thanks to its inclusion of creatine monohydrate at a recommended daily dosage between 3 and 5 grams. (3) “I actually like that Optimum Nutrition is supporting both weight gain and muscle mass with its formulation,” notes Chelsea Rae Bourgeois, our expert reviewer. “It can be wise for athletes to target both fitness goals when trying to bulk up through the use of a mass gainer.”
Of course, the high calorie and carb counts do make this supplement less ideal for certain athletes. Plus, the included whey protein concentrate is less refined than, say, what you’d find in the best whey isolates. Studies report that whey concentrate can contain as little as 35% of actual protein content by weight, so if you’re looking for a weight gainer supplement with higher-quality protein, you may be better off with a different formulation. (4)
Taste
Serious Mass weight gainer is available in five different tastes, which is slightly above the average four flavors we’ve often seen with other mass gainer supplements. Our tester, a certified personal trainer, tried the Vanilla offering, citing enjoyable notes of sweetness without any major or off-putting callouts. “I enjoyed this mixture and think it can be an appealing pick for athletes,” they say. “The Vanilla option I tried was a middle-of-the-road taste that’s good enough for daily consumption but nothing I’d personally write home about.”
We also score Serious Mass at 3.5 out of 5 for taste given its compatibility with other flavors and ingredients. Our tester, for example, added a full serving to their midday smoothie recipe, noting no unwanted interactions between the Vanilla flavor profile and their fruits of choice. “You don’t need to worry about overpowering your blend, which gives you room to explore new smoothie recipes down the road,” they add.
Is it the best-tasting protein powder we’ve tested? No, but the shake is pleasant enough that you won’t find yourself fighting to get to the bottom of your cup.
Solubility
While our tester scores Serious Mass’ solubility at 4 out of 5, we do want to point out a major caveat — this mass gainer was blended with a countertop blender and not your typical shaker. “Each serving is 340 grams of powder alone, and the instructions call for 24 ounces of cold water, milk, or your beverage of choice,” they state. “Even my shaker bottle would be too small to accommodate these measurements, and I doubt the metal blender ball would be able to mix the powder thoroughly.”
Despite the need for heavier artillery, we are pleased with the consistency of this supplement once blending ceases. Our tester notes that your end product resembles a creamy milkshake with no present clumps or undissolved powder. “I do recommend pulsing this mixture a bit, though,” they add, “Just to ensure that every bit of powder is broken up and combined with the liquid.”
Price Per Serving
With prices starting at $5.25 per serving, Serious Mass is far more expensive than many of the best whey protein powders out there, albeit with vastly different calorie and carb counts. This price point may be too high for athletes on a budget, so it’s best to look at your finances to determine whether a mass gainer is your best option for higher calorie intake.
That said, we score Serious Mass at 3.5 out of 5 for this category since you do have different quantity options for your order, giving you space to buy in bulk up to 16 servings. Additionally, while the price is costly, you are getting some bang for your buck when it comes to the calories-per-cost ratio. Serious Mass delivers roughly 238 calories for every dollar spent, which is more accommodating than other mass gainer supplements that typically hover between 135:1 and 215:1.
If you’re really trying to stretch your dollar as efficiently as possible during your muscle-building journey, Serious Mass can be a viable option. Of course, though, we recommend using these supplements as actual supplements in that a majority of your calories and macronutrients should come from whole-food sources.
Third Party Testing & Lab Data
Optimum Nutrition, as a brand, offers multiple third-party tested products, such as its aforementioned Gold Standard Whey Protein and its Essential Amino Energy BCAA Powder. Unfortunately, Serious Mass is not third-party tested, leading us to rate the product at 2 out of 5 for the category. Third-party certification can be a good thing to look for when searching for optimal supplements, as these marks indicate that the supplement is free of any banned substances and the listed dosages are accurate.
Additionally, our independently accredited lab gives Serious Mass an overall C grade in relation to the over 150 products tested. This mid-grade score mostly stems from Serious Mass scoring in the top 50% for the presence of heavy metals. However, the mass gainer scored highly in other categories, including within the top 10% for label accuracy as well as the presence of pesticides, phthalates, and bisphenols.
What to Consider Before Buying Optimum Nutrition Serious Mass
Like any supplement purchase, there are a few things to consider before adding Optimum Nutrition Serious Mass to your cart. Whether fine-tuning your nutrition for bulking or just trying to add some weight to your frame, here are some factors worth thinking through before finalizing your purchase.
- Calorie Count: Athletes have heightened energy requirements exceeding the average individual, with male and female athletes commonly consuming upwards of 3,000 and 2,700 calories daily, respectively. (5) That said, you’ll need to ensure your mass gainer is working alongside your regular intake rather than constantly putting you at a caloric surplus, especially when trying to maintain or lose weight.
- Nutrient Profile: Every mass gainer can have different macronutrient breakdowns, so you’ll want to look and see if the counts align with your goals and needs. For example, if a mass gainer is high in carbohydrates, that may not be the best solution for those following a keto diet.
- Fitness Goals: Mass gainers, as the name suggests, are designed to help you increase caloric intake when you cannot reach your desired totals through whole foods alone. The uptick in calories isn’t ideal for those on a weight loss journey, so think through your fitness aspirations before pouring yourself one of these dense protein shakes.
- Price Per Serving: On average, mass gainers cost roughly $5.13 per serving, making them one of the more expensive supplement categories on the market. No sports nutrition product is worth emptying your bank account, so run some numbers prior to purchase to ensure you can comfortably afford your shake of choice.
Optimum Nutrition Serious Mass Vs. Competitors
Searching “mass gainer” online will deliver multiple results from different brands, so comparing products side-by-side can be helpful when trying to narrow down your decision. Below, we’ve outlined two popular weight gainer supplements that match up comparably to Serious Mass — Dymatize Super Mass and Transparent Labs Mass Gainer.
| Optimum Nutrition Serious Mass | Dymatize Super Mass | Transparent Labs Mass Gainer | |
| Price Per Serving | Starting at $5.25 | Starting at $4.37 | $5.33 |
| Serving Size | 340g (≅2 scoops) | 333-335g (2.5 scoops) | 187-194g (2 scoops) |
| Calories Per Serving | 1,250-1,260 | 1,280 | 730-750 |
| Protein Per Serving | 50g | 52g | 51-53g |
| Carbohydrates Per Serving | 251-253g | 245g | 106-110g |
| Fat Per Serving | 5-6g | 10-11g | 13-14g |
| Available Flavors | Banana, Chocolate, Chocolate Peanut Butter, Strawberry, Vanilla | Gourmet Vanilla, Rich Chocolate, Fruity Pebbles | Chocolate Glaze Donut, Sweet Vanilla |
| Third-Party Testing | None | Informed Choice | Informed Choice |
As one of our favorite mass gainers overall, Transparent Labs Mass Gainer can be a high-quality protein option thanks to its roughly 2:1 carbs-to-protein ratio, approachable calorie counts between 187 and 194 calories, and third-party accreditation from Informed Sport. That said, Serious Mass may be a better pick for those really trying to increase their intake given the difference in formulation density. Plus, there are just two flavors to choose from with Transparent Labs while Optimum Nutrition offers Serious Mass in five varieties.
Dymatize Super Mass features comparable calorie, protein, and carbohydrate counts to Serious Mass, and we appreciate the sub-$4.40 price per serving. However, the higher fat count does leave us with some hesitations. “You’re getting 90 to 99 calories from fat with this powder,” notes Chelsea Rae Bourgeois, our expert reviewer. “While the carbs are the main driving factor here, it’s important to proceed with caution when trying to add these supplements to your regimen, especially if you’re conscious about your daily caloric intake.”
Places to Buy Optimum Nutrition Serious Mass
Optimum Nutrition Serious Mass is available online directly from the brand’s retail site. You can also find this supplement from select third-party retailers, including Amazon, DICK’S Sporting Goods, GNC, Walmart, and others.
Customer Experience and Brand Reputation
As a sports nutrition brand, Optimum Nutrition produces some of the best pre-workout supplements, protein powders, and creatine supplements on the market today. The brand has garnered a faithful following thanks to its approachable price points, impressive flavors, and easy-to-read ingredients list. To reach ON with any inquiries, you can utilize the support ticket link found near the bottom of the brand’s retail site or call 1-800-705-5226.
Like other Optimum Nutrition products, Serious Mass has remained a popular pick for fitness enthusiasts, earning a 4.5 out of 5 rating on Amazon based on over 51,000 customer reviews. “It tastes like melted ice cream,” notes one response. “It mixes easily and is priced comparatively.”
Our Final Verdict on Optimum Nutrition Serious Mass
Thanks to its high calorie-to-cost ratio and appealing flavor, we feel Optimum Nutrition’s Serious Mass weight gainer supplement can be a great product for athletes looking to ingest more calories while also aiming to get the most bang for their buck. The carbohydrate counts need to be taken into consideration, but if you’re okay with higher macro counts, this is a worthwhile option to consider.
When looking at a mass gainer supplement for your personal regimen, always ensure that the listed macronutrients and calories align with your goals. You don’t want to sign up for a product only to have it throw off your progress. Also, these supplements are more expensive than your average protein powder, so take a look at your finances before adding a pick to your cart.
Optimum Nutrition Serious Mass FAQs
When should I take Optimum Nutrition Serious Mass?
Optimum Nutrition Serious Mass can be used between meals to add to your daily caloric intake or as a post-workout beverage to support your recovery needs. Of course, make sure that your daily intake isn’t justified by supplementing with this calorie-dense weight gainer supplement.
How much does Optimum Nutrition Serious Mass cost?
Serious Mass is available online in four-, six, and 16-serving containers with costs per serving starting at roughly $5.25.
Can I drink Optimum Nutrition Serious Mass every day?
Yes, you can consume this ON mass gainer daily provided you’re keeping tabs on your caloric intake from other sources such as whole foods and other sports nutrition supplements.
References
- Mayo Clinic Staff. (2023, December 13). Creatine. Mayo Clinic. https://www.mayoclinic.org/drugs-supplements-creatine/art-20347591
- Arnold, A. R., & Chassaing, B. (2018). Maltodextrin, modern stressor of the intestinal environment. Cellular and Molecular Gastroenterology and Hepatology, 7(2), 475–476. https://pmc.ncbi.nlm.nih.gov/articles/PMC6409436/
- Naderi, A., de Oliveira, E. P., Ziegenfuss, T. N., & Willems, M. E. T. (2016). Timing, Optimal Dose and intake duration of dietary supplements with evidence-based use in sports nutrition. Journal of Exercise Nutrition & Biochemistry, 20(4), 1–12. https://pmc.ncbi.nlm.nih.gov/articles/PMC5545206/
- Carunchia Whetstine, M. E., Croissant, A. E., & Drake, M. A. (2005). Characterization of dried whey protein concentrate and isolate flavor. Journal of Dairy Science, 88(11), 3826–3839. https://pubmed.ncbi.nlm.nih.gov/16230688/
- Eating for peak athletic performance. News | UW Health. (2019, March 4). https://www.uwhealth.org/news/eating-for-peak-athletic-performance
