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Getting enough calories to actually gain weight can feel like a second job when your metabolism runs fast or your appetite is small. You need a shake that packs real nutrition into a single serving without forcing you to down gallons of liquid or deal with a stomachache afterward. This guide cuts through the marketing to find the fast weight gainer that delivers on its calorie and protein promises.
I’m Rikta — the founder and writer behind FitlyFast. This guide is built by comparing the manufacturers’ published specifications and the patterns across verified customer reviews, so you get each pick’s real strengths and trade-offs instead of marketing spin.
Every pick here was chosen for its honest serving size and clear macros, so you can find the best fast weight gainer that matches your daily calorie target and your budget without guesswork.
Our Picks at a Glance
How To Choose The Best Fast Weight Gainer
Not all mass gainers are built the same. One scoop from a budget tub might deliver only a few hundred calories, while a premium formula packs over 1,200 calories and 60 grams of protein. Here is what to check before you buy.
Calorie Density Per Serving
A fast weight gainer should provide at least 1,000 calories per serving to make a real dent in your daily surplus without requiring you to drink two or three shakes. Check the scoop size and the exact calorie count on the nutrition label — not the tub weight.
Protein Quality and Carb Source
The protein blend matters. Whey digests quickly for post-workout recovery, while casein provides a slow-release stream of amino acids throughout the day. On the carb side, look for complex carbohydrates (like tapioca maltodextrin or oat flour) instead of simple sugars that spike your blood sugar.
Mixability and Palatability
A thick, chalky shake is hard to finish every day. Real owner feedback shows that a grain-free, smooth texture and a flavor that tastes like a milkshake rather than medicine are the difference between sticking with your plan and letting the tub gather dust in the cupboard.
Quick Comparison
| Model | Best For | Calories Per Serving | Protein Per Serving | Weight | Amazon |
|---|---|---|---|---|---|
| Optimum Nutrition Gold Standard Pro Gainer★ Best Overall | Consistent daily gains | 650 | 60g | 5.09 lb | Amazon |
| Optimum Nutrition Serious MassTop Performer | Proven track record | 1,200+ | 50g | 6 lb | Amazon |
| Rule 1 Proteins Mass GainerBudget Champion | Serious calorie surplus | 1,220+ | 40g | 6 lb | Amazon |
| Dymatize Super Mass Gainer | Ultra-high calorie density | 1,290 | 52g | 6 lb | Amazon |
| NAKED Chocolate Peanut Butter Mass | Natural, clean ingredients | 1,280 | 50g | 8 lb | Amazon |
| Ronnie Coleman King Mass XL | High protein + added creatine | 1,000+ | 60g | 10 lb | Amazon |
| RIVAL NUTRITION Clean Gainer | Lean gains, gentle on stomach | 560 | 30g | 12 lb | Amazon |
| Mutant Mass Weight Gainer | Full food matrix, low sugar | 1,100+ | 56g | 15 lb | Amazon |
In‑Depth Reviews
1. Optimum Nutrition Gold Standard Pro Gainer, Vanilla Custard
Our pick — over 4.5★ from 650+ verified ratings; the strongest balance of quality and price.
The crowd-pleasing gainer that balances high protein with easy mixing and a rich vanilla taste.
This is the pick that owners consistently call tasty and effective. The Gold Standard Pro Gainer delivers 650 calories and a full 60 grams of high-quality protein per serving — a blend of fast and slow-digesting proteins — with less than 8 grams of sugar. That protein count is among the highest in this lineup, making it ideal for serious muscle repair and recovery. The 80-plus grams of carbohydrates per serving help replenish glycogen without a sugar crash.
You can gain weight without feeling stuffed, thanks to the Optimum Nutrition Gold Standard Pro Gainer. It delivers 60 grams of protein and less than 8 grams of sugar per serving, with a moderate calorie count that fits into a daily diet more easily than extreme bulkers. The Vanilla Custard flavor draws consistent praise — one owner described it as “very rich and creamy” and another noted it goes down “without gagging.” Buyers report gaining noticeable weight quickly; one owner saw 5 pounds in 6 days using just one shake daily. This is a balanced daily driver that owners actually enjoy drinking, making it the best pick for most users.
What owners love most
- Rich, creamy flavor that mixes smoothly without chalky texture
- 60g of protein per serving supports steady muscle repair
- Less than 8g of sugar per serving keeps shake clean
A note on portions
- Serving size yields 14 servings per tub, not the 28 pictured on the label
- At 650 calories per serving, you may need two shakes for a bigger surplus
Your daily driver: Reach for this if you want a great-tasting, high-protein gainer that is easy to drink every day without feeling overly full.
Think twice if: You need a single shake to deliver over 1,000 calories — here you will need to double up or add mix-ins.
2. Optimum Nutrition Serious Mass, Chocolate, 6LB
The hyper-caloric classic that has helped tens of thousands pack on size with over 1,200 calories per shake.
If you want a massive single-shake surplus with added creatine, the Optimum Nutrition Serious Mass is the heavyweight champion. Every two-scoop serving delivers over 1,200 calories, 50 grams of blended protein, and more than 250 grams of carbohydrates to refuel glycogen stores and support sustained energy. It also packs creatine, glutamine, BCAAs, and over 20 essential vitamins and minerals — making it a comprehensive bulk-phase tool rather than a simple calorie filler. At 6 pounds, this tub is among the most compact in the group for its calorie density; owners mention that a single tub lasts roughly 16 days if using two scoops daily. skip it if you prefer a lower-calorie option that fits easily into a daily diet.
The taste and mixability earn consistently high marks, with owners calling the chocolate flavor smooth and milkshake-like when blended with milk. The side effect that comes up most often is gas, which is common with high-carb mass gainers. The powder is dense and a blender is strongly recommended for smooth results.
Mass-building power
- Over 1,200 calories, 50g protein, and 250g+ carbs per serving for serious surpluses
- Includes creatine, glutamine, BCAAs, and 20+ vitamins and minerals
- Thousands of verified buyers call it effective for rapid weight gain
What to watch for
- Side effects of gas are commonly reported with a full serving
- Mixing by hand is difficult — a blender is nearly essential
Bulk-phase essential: Choose this if you have a very fast metabolism or struggle to eat enough whole food and need a proven, comprehensive surplus shake.
Skip if: You prefer a lower-carb or lower-calorie shake — this is a full-blast mass builder.
3. Rule 1 Proteins Mass Gainer, Chocolate Fudge, 8 Servings
A no-frills calorie bomb that packs over 1,220 calories per serving at a price that is tough to top.
This is the value play for those who need a massive calorie surplus without a massive price tag. Each serving delivers over 1,220 calories, more than 250 grams of complex carbohydrates, and 40 grams of all-whey protein with 9 grams of naturally occurring BCAAs. The 6:1 carb-to-protein ratio is designed for the hard gainer who needs a lot of energy fuel. It also includes pure creatine monohydrate for strength support, a premium addition rarely found at this price tier.
Taste is where the NAKED Chocolate Peanut Butter Mass shines. Buyers describe the Chocolate Fudge flavor as “amazing” and “like a chocolate milkshake.” One owner gained 6 pounds in two weeks, going from 162 to 168 pounds, and reported increases of 15 pounds on their deadlift and 10 pounds on their bench — without blood sugar spikes or bloating. The catch is that this tub contains only 8 servings, so it empties fast for daily users. A blender is also recommended because the powder can settle if shaken ahead of time. This is the one to reach for if you want the cleanest ingredient list with real food carbs and no artificial sweeteners.
Why it wins on value
- Over 1,220 calories and 250g complex carbs per serving for maximum surplus
- All-whey protein with 9g BCAAs plus pure creatine monohydrate
- Customers note real strength gains without bloating
Trade-offs to know
- Only 8 servings per tub — you will be reordering often
- Requires a blender for best texture; settling occurs if pre-made
Budget bulk: Grab this if price is your top concern but you still want real results, creatine included.
Not for you if: You want a long-lasting tub or prefer a more balanced protein-to-carb ratio.
4. Dymatize Super Mass Gainer, Fruity Pebbles, 6 Pound
The calorie king at 1,290 per serving, with a Fruity Pebbles flavor that stands out from the chocolate crowd.
If you have struggled to gain weight and need the absolute highest calorie density in a single shake, this is it. Each serving of the Dymatize Super Mass Gainer delivers 1,290 calories, 52 grams of protein, and 248 grams of carbohydrates. It also provides 10.7 grams of BCAAs including 5.1 grams of Leucine to activate muscle protein synthesis, plus 14 vitamins and minerals for recovery support. The 6-pound tub yields 8 servings, making this a pure bulk-phase weapon.
Flavor is a fun departure from the usual chocolate and vanilla. The Fruity Pebbles taste reminds owners of the milk left at the bottom of a bowl of sweet cereal. One owner called it “one of the best protein powders I have used so far” when mixed with almond milk. Results are tangible: a buyer reported that this gainer helped stop weight loss and add 10 pounds in one month. The powder is very thick and heavy, so half servings in a shaker bottle are better than full scoops, and a blender is recommended to avoid gunking up.
Pound-packing power
- 1,290 calories, 52g protein, and 248g carbs per serving — the densest in this list
- Fun Fruity Pebbles flavor that actually tastes great with water or milk
- Includes 14 vitamins and minerals plus high BCAAs for recovery
Handling notes
- Only 8 servings per tub; heavy powder requires a blender
- Full scoop is very thick — half servings work better in standard shakers
For the hard case: Choose this if you have tried other gainers without results and need the maximum calorie punch in one shake to finally move the scale.
pass on it if: You want a lighter, easier-to-mix option or need more than 8 servings per tub.
5. Ronnie Coleman Signature Series King Mass XL, Vanilla Ice Cream, 10 Pound
The vanilla-based bulk builder that matches 60g of protein with added creatine and glutamine for strength.
This is the option for lifters who want more than just calories — they want performance enhancers built into every scoop. The King Mass XL provides over 1,000 calories and 60 grams of high-quality protein per serving from a blend of whey concentrate, isolate, and casein. That dual-release protein mix means fast absorption after a workout and slow-release amino acids overnight. It also includes Creatine Ethyl Ester Malate and Glutamine to support strength, recovery, and muscle hydration. At 10 pounds, this is one of the larger tubs on the list, giving you more servings per purchase.
Owners praise the taste, calling the vanilla “pretty neutral” and versatile enough to blend with fruits or coffee for variety. The mixability is decent, with some clumps that are better than most mass gainers in this category. One buyer summed it up: “best value mass gainer by far.” The added performance ingredients make this a solid choice for intermediate and advanced lifters looking to support heavier training loads during a bulk.
Lifter-friendly formula
- 60g dual-release protein per serving supports both fast and slow muscle repair
- Added creatine and glutamine for strength, recovery, and hydration
- Neutral vanilla flavor blends well with fruit or coffee
Mixability nuance
- Some clumping can occur — a blender gives the smoothest texture
- At over 1,000 calories, it is a heavy shake for some stomachs
For the dedicated lifter: Choose this if you are training heavy and want a gainer that supports strength gains with creatine and glutamine on top of the calorie surplus.
Not for you if: You just want a simple calorie source without added performance ingredients.
6. NAKED Chocolate Peanut Butter Mass, 8 Pound
The all-natural gainer with 1,280 calories and a short ingredient list you can actually pronounce.
If you avoid artificial sweeteners, flavors, and colors, this is the mass gainer for you. The NAKED formula relies on organic tapioca maltodextrin for carbohydrates — no wheat fillers — plus a clean protein blend of whey, micellar casein, and peanut flour. Each serving delivers 1,280 calories, 50 grams of protein, 256 grams of complex carbs, and 9.6 grams of BCAAs. It is also GMO-free, soy-free, and gluten-free, setting a high bar for ingredient transparency.
The taste wins consistent praise. One owner said it tastes exactly “like a Reese’s candy,” and another noted it blends up thick like a peanut butter milkshake. Results are real: reviewers point out gaining up to 15 pounds of muscle, with one owner gaining 5 pounds in the first month. The trade-off is the sugar content — several owners note it has too much sugar for their preference, and the coconut sugar it uses still adds sweetness. The powder is filling, so sipping slowly over 30 minutes is the recommended approach.
Clean ingredient philosophy
- No artificial sweeteners, flavors, or colors; GMO-free and soy-free
- Organic tapioca maltodextrin provides clean complex carbs without wheat
- Rich chocolate peanut butter taste owners compare to a Reese’s candy
Honest caution
- Sugar content is noted as high by several buyers — check the label
- Very thick shake; sipping slowly is advised for comfortable digestion
Ingredient-first choice: Reach for this if you prioritize clean, organic ingredients and a short label with no artificial anything.
Think twice if: You are watching your sugar intake closely — the sugar level draws mixed feedback.
7. RIVAL NUTRITION Clean Gainer, Soft Serve Vanilla, 12 Pound
The easy-to-drink lean gainer with 560 clean calories that mixes easily without a blender.
Not everyone wants or needs 1,200 calories in one sitting. This clean gainer from Rival Nutrition is designed for controlled, lean gains with 560 quality calories per serving from premium proteins, fast-fueling carbohydrates, and energy-packed lipids. With 30 grams of protein per serving, it is a lighter option that works well for those who want a smaller calorie surplus each day or for smaller-framed individuals. At 12 pounds, this is one of the largest tubs with decent value per serving.
The taste is a highlight — owners describe it as “like melted vanilla milkshake” and not artificial. The real advantage is the mixability: no blender needed, just a shaker. One owner who aims for 2,250 to 2,500 calories from whole food plus this shake hits roughly 3,000 calories per day and reports excellent strength gains. A few shoppers say it is very sweet and that the sucralose can cause nausea for sensitive stomachs, so start with a half scoop if you are unsure.
Controlled surplus approach
- 560 calories per serving is perfect for smaller daily surpluses or light frames
- Mixes easily with a shaker — no blender required for a smooth drink
- Melted milkshake flavor without artificial aftertaste
Sensitivity note
- Contains sucralose; some buyers report stomach pain or nausea
- Very sweet taste may be off-putting to some palates
Gentle everyday gainer: Choose this if you want a light, easy-to-mix gainer that fits into a whole-food diet without overwhelming your stomach.
Not for you if: You need a high-calorie single shake for rapid weight gain or if you are sensitive to artificial sweeteners.
8. Mutant Mass Weight Gainer, Strawberry Banana, 15 Pound
The multi-award-winning mass gainer that packs whole-food carbs and delivers over 1,100 calories per serving.
Mutant Mass delivers over 1,100 specially engineered calories per serving with 56 grams of protein from a whey and casein blend, plus 192 grams of clean carbohydrates — and it has 52% less sugar than previous formulas. The carb profile includes whole-food sources like barley starch, sweet potato, and rolled oats, plus waxy maize, MCTs, and Colostrum. Sold in over 100 countries, this 15-pound tub is the largest in this guide, providing exceptional value per serving for long-term use. It is a best-seller for a reason, but it’s not for you if you prefer a smaller tub that empties faster.
Texture and mixability earn strong marks. Owners say it mixes easily with water or milk for a smooth, non-gritty shake. One petite female buyer reported effective weight gain in 1 to 2 months, and another called it “my mass gainer” for its perfect two-scoop serving size. The Strawberry Banana flavor is a hit, but be aware that the strawberry variant specifically draws occasional complaints about a cloying taste. The powder is filling enough to keep you full between meals without ruining your appetite.
Long-term bulking value
- 15 pounds per tub delivers exceptional servings-per-dollar value
- Whole-food carb sources (barley starch, sweet potato, rolled oats) for cleaner fuel
- 56g protein blend with whey and casein for fast and sustained release
Flavor heads-up
- Strawberry Banana is a polarizing flavor; some owners find it too sweet
- Tub is very large — storage space is something to consider
Bulk-buy champion: Reach for this if you want the best long-term value with whole-food carbs and a proven 15-pound supply for months of consistent use.
look elsewhere if: You dislike the Strawberry Banana flavor — check the chocolate or vanilla alternatives first.
Understanding the Specs
Calorie Density Per Serving
This is the single most important number in a fast weight gainer. A “high calorie” product typically delivers 1,000 to 1,300 calories per serving. The number tells you how close you get to your daily surplus target with just one shake. A 650-calorie option (like the Gold Standard Pro Gainer) works for lighter needs, while a 1,290-calorie shake (like Dymatize Super Mass) is built for extreme hard gainers.
Protein Blend and Carb Source
Protein quality matters for muscle repair. Whey digests fast for post-workout, while casein releases amino acids slowly over hours. On the carbohydrate side, complex carbs like organic tapioca maltodextrin or rolled oats provide steady energy without the blood sugar spike of simple sugars. A 6:1 carb-to-protein ratio (like Rule 1 Mass Gainer) prioritizes calorie density, while a more balanced ratio suits leaner goals.
Mixability and Palatability
A gainer that clumps or tastes artificial is hard to drink every day. The best formulas mix smoothly with a shaker or blender and have a flavor that owners actually enjoy — like chocolate milkshake, vanilla custard, or fruity cereal milk. The reviews consistently show that taste and texture are the difference between finishing your tub and letting it sit in the cupboard.
Servings Per Container
The total tub weight (5 to 15 pounds) does not tell you how many shakes you get. Always check the serving size on the label. Some gains pack 28 servings in a 6-pound tub, while others give only 8 servings for the same weight because the serving size is larger. If you plan to drink one shake daily, calculate how often you will need to reorder before you buy.
FAQ
How fast will I see results with a fast weight gainer?
Can I use a mass gainer if I have a sensitive stomach?
How do I mix a mass gainer without getting clumps?
What is the difference between a weight gainer and a protein powder?
Should I take a mass gainer before or after a workout?
Are mass gainers safe for women?
How many servings are actually in a tub?
Can I combine a mass gainer with whole food meals?
Final Thoughts: The Verdict
For the majority of shoppers, the fast weight gainer winner is the Optimum Nutrition Gold Standard Pro Gainer because it delivers 60 grams of high-quality protein with a great vanilla custard taste and less than 8 grams of sugar — a balanced daily driver that owners actually enjoy drinking. If you want a massive single-shake surplus with added creatine, grab the Optimum Nutrition Serious Mass. And for the cleanest ingredient list with real food carbs and no artificial sweeteners, the NAKED Chocolate Peanut Butter Mass is the one to reach for.
How We Picked
We do not accept paid placement. Every pick is matched to a real buyer and a real use-case; we do not hands-on test units.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of July 2026. Pricing: not shown on this page (it changes often); check the current price via the retailer link.
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