10 Best Weight Gain Protein Powder in The UK

Last updated on 02/08/2025

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Optimum Nutrition Serious Mass Protein Powder High Calorie Mass Gainer with Vitamins, Creatine and Glutamine, Chocolate Peanut Butter, 16 Servings, 5.45 kg, Packaging May Vary

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Why We Love It

Supports muscle growth and performance.
Healthy, low-fat, high-calorie content.
Six tasty, varied flavors.

Main Highlights

Low fat mass gainer with over 1250 CALORIES and 50g of PROTEIN per serving to support muscle growth* plus 3 grams of CREATINE MONOHYDRATE to support performance**
No added sugar protein powder formula with 25 vitamins and minerals and less than 5g fat per serving, plus over 250 grams of CARBOHYDRATES helping support muscle recovery***
Serious Mass protein powder comes in 6 flavours (banana, chocolate peanut butter, chocolate, cookies & cream, strawberry and vanilla) & contains sweetener
To prepare weight gainer mix 2 scoops with 710 ml of water or plant milk, add fruit or nut butters for a tasty and calorific post workout or between meals protein smoothie
Source EFSA Journal *2010;8(10):1811; 2011;9(6):2203; ** 2011;9(7):2303; ***2011; 9(7):2303

USN Hyperbolic Mass Strawberry Cheesecake 6kg: High Calorie Mass Gainer Protein Powder for Muscle Building and Weight Gain - Improved Formula & Flavour with 7.5g Creatine Monohydrate and Less Sugar

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Why We Love It

Uncompromised taste with muscle mass.
High calorie for quick results.
Nutrition-rich performance booster.

Main Highlights

Our best mass gainer yet: Our best-tasting mass gainer is for those who want to increase their muscle mass, but don't want to compromise on the taste of their protein drink.
High calorie bulk powder: With up to 1183 calories our all-in-one mass and weight gainer is ideal for individuals who struggle to gain muscle mass and want a fast-acting, easy-mixing and effective formula.
Amazing taste, great results: The improved formula of our delicious strawberry flavour mass gainer provides a greater post-workout effectiveness, with a smoother taste - all delivered with less Sugar.
A weight gainer with nutrition: Our mass protein powder contains a massive 60g of protein per serving, partnered with 7.5g of Creatine and 18 vitamins and minerals (B12, B6, C, Magnesium, Iron) to help you be at your best.
For best results: To get the best results from Hyperbolic Mass, take 1 servings daily, either after training or as a snack between meals. Simply mix 4 scoops (300g) of the protein powder with 900ml of cold water and enjoy.

Reflex Nutrition Instant Mass Heavyweight - Mass Gainer - Over 1000 Kcal per Serving, 60g Protein, Creatine - High Calorie Post Workout or Before Bed Protein Shake (Chocolate Perfection, 5.4 kg)

Why We Love It

Promotes muscle gain effectively.
Ensures nutrient-rich intake.
Quality ensured from Reflex Nutrition.

Main Highlights

Engineered for Gains: This seamless protein shake mix is specifically formulated to accelerate muscle and weight gains and improve post-workout recovery, enhancing overall workout performance for the dedicated, hard gainer and serious athlete alike
Excellent Nutrition Profile: Packed with quality ingredients, each protein shake serving delivers over 1000 kcals, 200g of complex carbohydrates, 60g of muscle gain protein, critical EAAs, creatine, 18 vitamins and minerals (B12, B6, C, Iron, Zinc)
Outstanding Taste Sensation: Our Chocolate Perfection mass gainer flavour isn't just a treat for your taste buds - it's a deliciously creamy escape into indulgence with every sip, all while you are fueling your body for mass gain and muscle recovery
Optimal Timing for Maximum Impact: Consume Instant Mass Heavyweight high protein shake between meals for a positive nitrogen balance, 20-30 minutes post workout for best results or 45-60 minutes before sleep to aid overnight muscle maintenance
Trusted Quality Assurance: Reflex Nutrition's promise to quality means whey protein powder from grass-fed cows - Protein Sources are Glutamine Peptides, Whey Protein Concentrate, Milk Protein, Hydrolysed Whey Protein
Produced in an Informed Sport Registered Facility - Suitable for vegetarians and Halal certified - Zero added sugars, artificial colors, or soy protein, assuring a conscientious choice of weight gainer for your muscle-building objectives

Kinetica Sports OatGain Weight Gainer - Chocolate Caramel Flavour | 620 Cal, 47g Protein & 78g Carbs/Serve, 15 Serving/2.4Kg | Optimum Grass Fed Protein Supplement | High Calorie & Easy Mixability

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Why We Love It

Delicious Chocolate Caramel Nut.
Easy to mix.
Repairs muscles, replenishes energy.

Main Highlights

Irresistible Flavour for Maximum Enjoyment: Kinetica Sports OatGain Mass Gainer comes in two mouthwatering flavours: Chocolate Caramel Nut and Raspberry Yoghurt. Each delivers a rich, satisfying taste and aroma, making it easy and enjoyable to fuel your body with extra calories and nutrients to support high training loads.
Smooth & Easy Mixability: Experience hassle-free mixing with Kinetica Sports OatGain Weight Gainer. Whether you prefer water, milk, or milk alternatives, our mass gainer powder mixes easily with milk or water for a high protein, high calorie shake in seconds.
High-Calorie Fuel for Muscle & Energy: Each serving of Kinetica Sports OatGain mass gainer provides 600+ calories and 46g of protein to help you gain weight, increase overall muscle mass and replenish your energy stores, making it ideal for intense workouts and recovery. Kinetica Sports Oatgain mass gainer contains only 6.4g of sugar per serving.
Convenient & Versatile for Any Lifestyle: Kinetica OatGain weight gainer is perfect for anyone looking to intake a high volume of calories for weight gain or energy regeneration. It’s suitable for vegetarians and can be used as a post-workout shake, meal replacement, or mid-day snack. Simply mix one serving with water, milk, or your preferred beverage for a quick and nutritious option.
Quality Assured & Batch-Tested for Safety: Kinetica Sports OatGain mass gainer is batch-tested under the Informed-Sport testing program to ensure that every batch complies with WADA’s high standards. You can trust that OatGain is free from banned substances and made with quality ingredients to fuel your training safely and effectively.

Optimum Nutrition Serious Mass Protein Powder High Calorie Mass Gainer with Vitamins, Creatine and Glutamine, Strawberry, 8 Servings, 2.73 kg, Packaging May Vary

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Why We Love It

Supports muscle growth and performance.
Promotes recovery with carbohydrates.
Offers tasty, diverse flavor options.

Main Highlights

Low fat mass gainer with over 1250 CALORIES and 50g of PROTEIN per serving to support muscle growth* plus 3 grams of CREATINE MONOHYDRATE to support performance**
No added sugar protein powder formula with 25 vitamins and minerals and less than 5g fat per serving, plus over 250 grams of CARBOHYDRATES helping support muscle recovery***
Serious Mass protein powder comes in 6 flavours (banana, chocolate peanut butter, chocolate, cookies & cream, strawberry and vanilla) & contains sweetener
To prepare weight gainer mix 2 scoops with 710 ml of water or plant milk, add fruit or nut butters for a tasty and calorific post workout or between meals protein smoothie
Source EFSA Journal *2010;8(10):1811; 2011;9(6):2203; ** 2011;9(7):2303; ***2011; 9(7):2303

The Bulk Protein Company

The Bulk Protein Company, SERIOUS GAINZ - Whey Protein Powder - Weight Gain, Mass Gainer - 30g Protein Powders (Chocolate, 5kg)

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Why We Love It

Builds muscle with high protein.
Promotes mass gain effectively.
Offers excellent value for money.

Main Highlights

30g PROTEIN PER SERVING TO HELP BUILD MUSCLE - Protein Isolate powder that contains 30 grams of high quality Protein per serving. A convenient and easy way to help you meet your daily protein needs. Use after training to quickly heal micro-tears in muscle tissues, which speeds up recovery, reduces muscle soreness and leads to stronger and bigger muscles over time.
PUT ON SIZE AND GAIN MASS - With 468 lean calories per serving, Serious Gainz protein powder is ideal when BULKING. Use as part of a balanced diet to help add body mass and increase weight gain. Contains 81g of carbohydrates which will help your body absorb the protein within, turning it into muscle mass to help towards improving your overall body composition.
PROTEIN SHAKE THAT TASTES GREAT - Add 3 scoops of powder to 400-500ml of water or milk and mix well to create a great tasting Protein Shake! Can also be enjoyed in smoothies, with oats or when added to a pancake mix. Protein powders don't have to be boring, so we made 10 different flavours for you to choose from.
HIGH QUALITY WHEY PROTEIN - Whey digests quickly and is rich in branched-chain amino acids (BCAAs). One of these BCAAs, Leucine, plays a major role in promoting muscle growth and recovery after resistance and endurance exercise. When amino acids are digested and absorbed into your bloodstream, they become available for muscle protein synthesis, which is the creation of new muscle.
EXCELLENT VALUE 5kg TUB WITH 40 SERVINGS - With up to a month's supply of high quality protein powder, we offer great value for your money compared with other brands. We recommend one serving per day to consistently meet your daily protein goal. Consume immediately post-training on workout days and between breakfast and lunch on non-workout days. Comes with scooper for measurements.

Optimum Nutrition Gold Standard Whey Protein, Muscle Building Powder with Naturally Occurring Glutamine and Amino Acids, Double Rich Chocolate, 29 Servings, 899 g, Packaging May Vary

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Why We Love It

Supports muscle gain and recovery.
Certified, low-sugar protein formula.
Variety of sizes, flavors.

Main Highlights

Optimum Nutrition’s Gold Standard 100% WHEY is the world’s best-selling protein powder* designed to support your fitness journey from day one.
FAST-ABSORBING whey protein with whey protein isolate as the main ingredient helps with muscle gain and supports recovery* after every training session.
The ON whey protein formula is Informed Choice certified, contains naturally-occurring BCAAs and GLUTAMINE and is LOW IN SUGAR and fat.
Available in a VARIETY OF SIZES and FLAVOURS: double rich chocolate, banana cream, vanilla ice cream, unflavored protein powder and more.
EASY & CONVENIENT: mix one scoop in 180-240 ml of cold water; best enjoyed in the morning or/and during the 30 minutes just before or immediately after training.
*Source: Euromonitor International Limited; Consumer Health 2023 edition, Sports Protein Powder category, % retail value shares, 2022 data.
** Source EFSA Journal 2010;8(10):1811; 2011;9(6):2203.

Myprotein Impact Whey Weight Gainer Protein (2.5kg (Pack of 1), Chocolate Smooth)

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Why We Love It

Promotes healthy weight gain.
Provides high-quality protein.
Convenient and redesigned packaging.

Main Highlights

31g of protein
50g of carbs
388 calories per serving

Applied Nutrition Critical Mass Professional - Weight Gain Protein Powder, High Calorie Weight Gainer, Lean Mass (2.4kg - 16 Servings) (Chocolate)

27% OffFree Shipping

Why We Love It

High-quality lean mass gainz.
New formula with whey isolate.
Tested for athletic assurance.

Main Highlights

THE UK'S MOST TRUSTED MASS GAINER FOR SERIOUS SIZE & STRENGTH – Critical Mass Professional is the ultimate high-calorie weight gainer, engineered for those who want to bulk up, increase muscle mass, and fuel intense workouts. This mass gainer supplement is trusted by hard gainers, bodybuilders, and athletes looking for serious results.
1,000+ CALORIES PER SERVING – PACKED WITH HIGH-QUALITY PROTEIN & CARBS – Delivers a caloric surplus essential for lean muscle gain. Each serving contains a blend of fast-absorbing and slow-digesting proteins, including ISO-XP Whey Isolate, to maximize muscle recovery and growth. Combined with a premium carbohydrate complex, it helps sustain energy levels and support muscle glycogen replenishment.
POWERFUL CREATINE & GLUTAMINE COMPLEX FOR PERFORMANCE & RECOVERY – Enhanced with Creatine Monohydrate, Critical Mass Professional boosts strength, endurance, and muscle power output for high-intensity training. Includes L-Glutamine & Glutamic Acid, key amino acids that aid muscle recovery, reduce fatigue, and support immune function.
OPTIMAL WEIGHT GAIN FORMULA FOR HARD GAINERS & ATHLETES – Whether you struggle to put on weight, need extra calories due to intense training, or want to bulk up, this high-calorie gainer provides the perfect macronutrient balance. Ideal as a post-workout shake, meal replacement, or between-meal supplement for continuous muscle fuel.
EASY MIXING & DELICIOUS FLAVOURS FOR MAXIMUM ENJOYMENT – Designed for convenience, this instantized protein powder mixes effortlessly in water or milk, creating a smooth, creamy texture with no lumps or grittiness. Available in 6 mouth-watering flavours: Chocolate, Banana, Vanilla, Chocolate Mint, Strawberry, and White Chocolate & Raspberry.
TESTED FOR ATHLETES: at Applied Nutrition we carefully select and monitor each product through our quality management system to bring you the highest level of assurance. Critical Mass Professional is no exception and is tested at an ISO 17025 accredited lab.

Applied Nutrition Critical Mass Professional - Weight Gain Protein Powder, High Calorie Weight Gainer, Lean Mass (2.4kg - 16 Servings) (Strawberry)

27% OffFree Shipping

Why We Love It

High-quality lean mass gainz.
New protein blend formula.
Available in six flavors.

Main Highlights

THE UK'S MOST TRUSTED MASS GAINER FOR SERIOUS SIZE & STRENGTH – Critical Mass Professional is the ultimate high-calorie weight gainer, engineered for those who want to bulk up, increase muscle mass, and fuel intense workouts. This mass gainer supplement is trusted by hard gainers, bodybuilders, and athletes looking for serious results.
1,000+ CALORIES PER SERVING – PACKED WITH HIGH-QUALITY PROTEIN & CARBS – Delivers a caloric surplus essential for lean muscle gain. Each serving contains a blend of fast-absorbing and slow-digesting proteins, including ISO-XP Whey Isolate, to maximize muscle recovery and growth. Combined with a premium carbohydrate complex, it helps sustain energy levels and support muscle glycogen replenishment.
POWERFUL CREATINE & GLUTAMINE COMPLEX FOR PERFORMANCE & RECOVERY – Enhanced with Creatine Monohydrate, Critical Mass Professional boosts strength, endurance, and muscle power output for high-intensity training. Includes L-Glutamine & Glutamic Acid, key amino acids that aid muscle recovery, reduce fatigue, and support immune function.
OPTIMAL WEIGHT GAIN FORMULA FOR HARD GAINERS & ATHLETES – Whether you struggle to put on weight, need extra calories due to intense training, or want to bulk up, this high-calorie gainer provides the perfect macronutrient balance. Ideal as a post-workout shake, meal replacement, or between-meal supplement for continuous muscle fuel.
EASY MIXING & DELICIOUS FLAVOURS FOR MAXIMUM ENJOYMENT – Designed for convenience, this instantized protein powder mixes effortlessly in water or milk, creating a smooth, creamy texture with no lumps or grittiness. Available in 6 mouth-watering flavours: Chocolate, Banana, Vanilla, Chocolate Mint, Strawberry, and White Chocolate & Raspberry.
TESTED FOR ATHLETES: at Applied Nutrition we carefully select and monitor each product through our quality management system to bring you the highest level of assurance. Critical Mass Professional is no exception and is tested at an ISO 17025 accredited lab.

8.7

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We scanned 928 products

We reviewed these offers relevant to the Weight Gain Protein Powder within online retailers such as Amazon, eBay and other local retailers, ensuring we covered all major brands and models. The products we selected come from trusted brands like Optimum Nutrition, USN, Reflex, Kinetica, The Bulk Protein Company, Myprotein, Applied Nutrition, all of which have a reputation for consistently delivering high-quality products that users love and innovative approaches for function & design.

For the best Weight Gain Protein Powder in the market, we considered we took a deep dive into 4641 online reviews , focusing on elements like user satisfaction, performance in real-world conditions, and long-term reliability. Our ranking also evaluates each review’s relevancy, authenticity, up-to-dateness and depth so that the comparison is more sound.

We concluded that:

The clear winner of our analysis is Optimum Nutrition Serious Mass Protein Powder High Calorie Mass Gainer with Vitamins, Creatine and Glutamine, Chocolate Peanut Butter, 16 Servings, 5.45 kg, Packaging May Vary. We love many things about this product by Optimum Nutrition. What sets it apart from the competition is Supports muscle growth and performance, Healthy, low-fat, high-calorie content, Six tasty, varied flavors.
The best value product for most shoppers and where user satisfaction is continuously the highest is USN Hyperbolic Mass Strawberry Cheesecake 6kg: High Calorie Mass Gainer Protein Powder for Muscle Building and Weight Gain - Improved Formula & Flavour with 7.5g Creatine Monohydrate and Less Sugar by USN based on online reviews by bloggers, experts and online shoppers.
The biggest bargain at the moment for Weight Gain Protein Powder and the best cost-to-value ratio is Applied Nutrition Critical Mass Professional - Weight Gain Protein Powder, High Calorie Weight Gainer, Lean Mass (2.4kg - 16 Servings) (Strawberry)at Applied Nutrition with a 27% discount.
Our list of the best Weight Gain Protein Powder is updated regularly to reflect new releases and changes in product availability, so be sure to check back often for the latest rankings and discounts.

10 Best Weight Gain Protein Powder in The UK

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SCI-MX Total Mass - Advanced Muscle Mass Gainer Protein Powder - Muscle Growth & Weight Gain - Chocolate • 32g Protein + 478 Calories per Serving • 2kg

Warrior Whey Protein Powder 500g - Up to 36g* Protein per Shake – Low Sugar - Muscle Growth and Recovery Drink - Amazing Taste - 20 Servings - GMP Certified (Strawberry Milkshake)

Bulk Complete Mass Gainer | Chocolate | 1kg | 45g Protein per Serving | 65g Carbohydrates | 500 kcal per Serving | High-Calorie Weight Gainer | Supports Muscle Growth & Maintenance | High Protein

Bulk Complete Mass Gainer | Strawberry | 1kg | 45g Protein per Serving | 65g Carbohydrates | 500 kcal per Serving | High-Calorie Weight Gainer | Supports Muscle Growth & Maintenance | High Protein

Boditronics Mass Attack Heavyweight Mass Gainer Powder for High Protein and High-Calorie Weight Gainer Protein Powder with 5g Creatine, BCAA, Glutamine and Beta Alanine (Strawberries and Cream)

The Bulk Protein Company SERIOUS GAINZ 2kg - Whey Protein Powder - Weight Gain, Mass Gainer - 30g Protein Powders - Bulk Protein Company (Banana, 2kg)

USN Muscle Fuel Anabolic All-In-One Muscle Mass Gainer, Strawberry Flavour - 2kg, 54g Protein Powder, 5g Creatine Powder & 5g BCAA Powder For Maximum Muscle Growth, Post Workout Recovery Drink Mix

Applied Nutrition Critical Whey Protein Powder 450g - High Protein Powder, Protein Milkshake, Muscle Building Supplement with BCAAs & Glutamine (450g - 15 Servings) (Strawberry)

Dymatize Super Mass Gainer Rich Chocolate 2943g - Weight-Gainer Pulver + Kohlenhydrate, BCAAs und Casein

We scanned 928 products

We concluded that: