MASS gainers
Applied Nutrition Critical Mass Professional 6kg
Best Mass Gainer UK 2026 — Complete Guide to Weight Gainers
Quick Answer
The best mass gainer in the UK is one that delivers high calories (800–1,200+ kcal per serving), adequate protein (40–60g), and quality carbohydrates that support training and recovery without excessive fillers or unnecessary additives.
Our #1 pick is Mutant Mass Extreme 2500 — the best all-round mass gainer for anyone serious about building size, strength, and bodyweight consistently while training hard.
Struggling to Build Size No Matter How Hard You Train?
Whether you have a fast metabolism that burns through everything you eat, you simply struggle to consume enough calories through food alone, or you have hit a frustrating plateau that training alone cannot break through — this is exactly where mass gainers come in.
This guide covers the best mass gainers available in the UK right now, chosen for anyone who wants to gain weight, build real muscle, and recover faster without spending their entire day forcing down meals. Whether you are a complete beginner, a hard-gainer, a woman looking to build lean muscle, or an experienced lifter in a serious bulking phase — there is a mass gainer on this list for your goal.
These calorie-dense shakes provide the protein, carbohydrates, and nutrients needed to maintain a consistent calorie surplus — the single most important requirement for muscle and weight gain.
👉 Want faster results? Pair your mass gainer with our Beginner Workout Plan to make sure every calorie turns into muscle.
What Is a Mass Gainer and Why Do You Need One?
A mass gainer (also known as a weight gainer) is a high-calorie supplement designed to help people who struggle to eat enough food to support muscle growth.
Muscle gain requires a consistent calorie surplus — consuming more calories than your body burns every single day. For many people, achieving that surplus through food alone is the biggest obstacle. Appetite, time, and practicality all get in the way.
Mass gainers make that surplus realistic, repeatable, and convenient.
Key Benefits
- Easy way to hit daily calorie targets without constant eating
- Supports muscle growth, strength, and recovery
- Often includes creatine, amino acids, and vitamins for added performance support
- Convenient post-workout or between meals — ready in minutes
If you struggle to hit your calorie target through food alone, a mass gainer is one of the most reliable ways to move both the scale and your training forward.
How to Choose the Best Mass Gainer for Your Goals
Your ideal mass gainer depends on your metabolism, your training intensity, and how aggressively you want to build.
Fast metabolism or struggling to gain any weight: Choose a high-calorie gainer (800–1,200+ kcal per serving) for faster, more aggressive weight gain.
Training hard and want strength alongside size: Look for gainers with added creatine and performance support ingredients for a complete training formula.
Prefer leaner, more controlled gains: Choose a product with balanced macros, higher protein content, and moderate calories to support quality muscle growth without excessive fat gain.
Top 5 Best Mass Gainers in the UK (2026)
1. Mutant Mass Extreme 2500 — Best Overall Mass Gainer UK
Our number one pick for anyone serious about building size.
Mutant Mass Extreme 2500 tops this list because it delivers exactly what a mass gainer needs to do — consistently and without compromise. With over 1,000 calories per full serving, a multi-source protein blend, and a complex carbohydrate matrix designed for sustained energy release, this is the most effective calorie-delivery formula on this list for anyone who needs serious nutritional support to grow.
It is not just about the numbers. Despite its calorie density, Mutant Mass Extreme 2500 mixes smoothly in a standard shaker with no clumping or sludge, and comes in multiple great-tasting flavours that make daily compliance genuinely easy. When a shake this powerful is also this enjoyable to drink, building the daily habit becomes effortless — and consistency is what produces results.
Why it’s number one:
- ✔ Over 1,000 calories per full serving
- ✔ Multi-source protein blend for sustained muscle support
- ✔ Complex carbohydrate matrix for energy and recovery
- ✔ Smooth mixability — no clumps, no grit
- ✔ Multiple great-tasting flavours
- ✔ Built for anyone who needs serious calorie support to build size
Best for: Anyone who struggles to hit a daily calorie surplus through food alone, hard-gainers and fast metabolisms, and anyone serious about building size and strength consistently.
👉 Shop Mutant Mass Extreme 2500
2. USN Hyperbolic Mass — Best All-in-One Performance Mass Gainer
The top choice for those who want size, strength, and recovery support in a single formula.
USN Hyperbolic Mass combines a high-calorie, high-protein formula with creatine monohydrate, essential amino acids, and a full micronutrient profile — making it a complete all-in-one training supplement rather than just a weight gainer. For anyone who trains consistently and wants their mass gainer to support gym performance as well as calorie intake, this formula delivers on both fronts in a single daily scoop.
Why it stands out:
- ✔ High-calorie formula ideal for consistent bulking
- ✔ Creatine monohydrate included for strength and performance
- ✔ Essential amino acids for muscle recovery support
- ✔ Full vitamin and mineral profile
- ✔ Outstanding taste and mixability with water or milk
Best for: Anyone who wants an all-in-one formula covering calories, protein, creatine, and recovery support. Ideal for those training 3–5 times per week who want a single product that does everything.
3. Applied Nutrition Critical Mass — Best Budget Mass Gainer UK
Serious calorie and protein delivery at a price that makes long-term bulking genuinely affordable.
With over 900 calories per full serving, 55g of premium dairy protein, L-glutamine, CLA, Bromelain digestive enzyme, and naturally occurring BCAAs and EAAs, Critical Mass delivers exceptional quality at one of the best price points on this list. Six flavour options and smooth mixability make it easy to commit to daily use.
Why it stands out:
- ✔ Over 900 calories per full serving
- ✔ 55g premium dairy protein per serving
- ✔ L-Glutamine and CLA included
- ✔ Bromelain digestive enzyme for improved absorption
- ✔ 6 great flavours — excellent mixability
- ✔ Outstanding value for money per serving
Best for: Anyone on a budget who needs high calories and solid protein without paying a premium price. Perfect for long-term consistent bulking where cost per serving matters.
👉 Shop Applied Nutrition Critical Mass
4. USN Muscle Fuel Anabolic — Best for Lean, Controlled Muscle Gains
The smart choice for anyone who wants quality muscle growth without excessive fat gain.
USN Muscle Fuel Anabolic delivers a carefully balanced blend of whey protein concentrate and isolate, complex carbohydrates, creatine monohydrate, essential amino acids, and a complete vitamin and mineral profile — at a more controlled calorie level than the higher-end gainers on this list. Ideal for those who are already progressing and want to keep their gains as lean and controlled as possible.
Why it stands out:
- ✔ Balanced calorie-to-protein ratio for lean muscle growth
- ✔ Whey protein concentrate and isolate blend
- ✔ Creatine monohydrate for performance support
- ✔ Complex carbohydrates and healthy fats
- ✔ Full amino acid and micronutrient profile
Best for: Anyone who wants controlled, lean muscle growth rather than aggressive weight gain. Ideal for those training consistently who want sustainable long-term gains.
👉 Shop USN Muscle Fuel Anabolic
5. Optimum Nutrition Serious Mass — Best from a Globally Trusted Brand
Proven, reliable, and backed by the world’s most trusted sports nutrition name.
Optimum Nutrition brings the same commitment to quality and ingredient transparency that made Gold Standard Whey the world’s best-selling protein powder. Serious Mass is a high-calorie, nutrient-dense formula that has been a bulking staple for years. A practical tip — if you are new to mass gainers or want more control over your calorie intake, start with a half serving and build from there.
Why it stands out:
- ✔ High-calorie formula from a globally trusted brand
- ✔ Quality protein and complex carbohydrates
- ✔ Vitamins and minerals for complete recovery support
- ✔ Flexible serving sizes to suit different calorie targets
- ✔ Rigorous quality control and full ingredient transparency
Best for: Anyone who wants a proven, trustworthy mass gainer from a brand with a long and well-established track record.
👉 Shop Optimum Nutrition Serious Mass
Fast vs Controlled Weight Gain: Which Approach Is Right for You?
Fast, Aggressive Gains (High-Calorie Approach)
Best if you struggle to gain any weight regardless of food intake, or want to push the scale upward as quickly as possible.
Top picks:
- Mutant Mass Extreme 2500
- USN Hyperbolic Mass
- Applied Nutrition Critical Mass
Best taken post-workout to support recovery and muscle growth when your body needs it most.
Gradual, Lean Muscle Gains (Controlled Approach)
Best if you want size alongside quality, with minimal fat gain and more precise control over your results.
Best options:
- USN Muscle Fuel Anabolic
- Whey protein combined with a creatine stack
Final Recommendations
| Goal | Best Pick |
|---|---|
| Best Overall | Mutant Mass Extreme 2500 |
| Best All-in-One Performance | USN Hyperbolic Mass |
| Best Budget Option | Applied Nutrition Critical Mass |
| Best for Lean Gains | USN Muscle Fuel Anabolic |
| Best Trusted Brand | Optimum Nutrition Serious Mass |
👉 Choose based on your goals, metabolism, and training intensity — then stay consistent and grow.
Best Weight & Mass Gainers in the UK – Reviews & Top Picks (2026)
Mutant Mass Extreme 2500 Review
Looking to go full beast mode?
Mutant Mass Extreme 2500 is the real deal for skinny guys and hard gainers who want to bulk up fast without spending their entire day force-feeding.
What Makes It a Monster?
This isn’t just another weight gainer — it’s a high-calorie powerhouse built to help you hit those massive calorie goals with ease. It delivers a solid blend of protein, carbs, and healthy fats, giving your body the fuel it needs to build serious muscle and recover like a machine.
Mixability & Flavour? Spot On.
You might expect a 2500-calorie shake to be a nightmare to mix…
But surprise! Even at full serving, it mixes smoothly in a standard shaker — no clumps, no sludge. Just a creamy, drinkable shake.
✅ Not too thick
✅ No lumps
✅ Comes in 4 epic flavours — all of them worth trying
Who’s It For?
If you’ve got a fast metabolism, struggle to eat enough, or just want to gain serious size without overthinking every meal, Mutant Mass Extreme 2500 is your go-to.
✅ Final Thoughts
Want to grow? This gainer delivers results.
Huge calories
Great taste
Clean mix
Just adjust your serving to match your calorie needs — then lift heavy, eat big, and grow bigger.
👉 Want to compare it? See our full breakdown in Mutant Mass vs Mutant Mass Extreme.
Optimum Nutrition Serious Mass Review
Ready to get serious about size?
Serious Mass by Optimum Nutrition does exactly what the name promises — it’s a trusted heavyweight in the world of mass gainers, and for good reason.
What’s Inside the Shake?
Each serving of Serious Mass delivers:
A calorie-packed formula
Quality protein and complex carbs
Vitamins and minerals for all-round recovery
This gainer doesn’t mess around — it gives you everything your body needs to train hard, recover fast, and grow bigger.
Perfect for Daily Calorie Goals
Struggling to eat enough throughout the day?
Serious Mass makes it way easier to hit your calorie target without stuffing down extra meals.
Especially great if you’re on a hard bulking plan or have a fast metabolism.
Trusted Quality You Can Rely On
What sets Serious Mass apart?
It’s made by Optimum Nutrition — one of the most respected brands in the supplement game.
Their rigorous quality control means you can be confident that what’s on the label is exactly what you’re getting — safe, effective, and clean.
Final Verdict
If you’re committed to your training and ready to take your bulking to the next level, Serious Mass is a solid pick.
✅ Trusted brand
✅ Tastes great
✅ Loaded with nutrients
✅ Easy way to smash your daily intake
It’s serious fuel for serious gains.
👉 Not sure how it stacks up? Read Mutant Mass vs Serious Mass for a direct comparison.
USN Muscle Fuel Anabolic Review
Looking for a lean mass gainer that works just as hard as you do?
USN Muscle Fuel Anabolic is a top-tier choice for guys who want to build size, boost strength, and recover faster — without piling on excess fat.
What Makes It So Effective?
This all-in-one formula is loaded with performance-enhancing nutrients, including:
🔹 Whey Protein Concentrate & Isolate
🔹 Complex Carbohydrates
🔹 Creatine Monohydrate
🔹 Essential Amino Acids
🔹 A full vitamin and mineral profile
Together, these support faster recovery, muscle growth, and improved workout performance — exactly what you want when bulking clean.
Taste, Texture & Mixability
No chalky aftertaste here.
Muscle Fuel Anabolic mixes up smooth and creamy, whether you go with water or milk. It’s a pleasure to drink, even after a tough session at the gym.
How It Performs in the Gym
From my experience:
I recovered quicker between workouts
Strength noticeably increased week by week
Extra energy in sessions thanks to the creatine boost
It’s not just a shake — it’s a full-blown muscle support system in one scoop.
Final Thoughts
USN Muscle Fuel Anabolic is a fantastic option if you want controlled muscle growth without going overboard on calories.
✅ Clean bulk friendly
✅ All-in-one formula
✅ Smooth taste and easy mix
✅ Ideal for serious training plans
Build lean size, train harder, and recover like a pro. This one delivers.
👉 Read our full USN Muscle Fuel Anabolic Review for ingredients, results, and who it’s best for.
USN Hyperbolic Mass Review
If you’re a hard gainer or someone who struggles to keep the scale moving, USN Hyperbolic Mass might just be your new best friend in the gym.
Taste & Mixability
Let’s start with the good stuff: this shake tastes incredible.
It’s rich, creamy, and honestly feels more like a treat than a supplement.
✔️ No grainy bits
✔️ Mixes smoothly with water or milk
✔️ Genuinely enjoyable every single time
When a mass gainer tastes this good, you’ll actually look forward to taking it — and that’s half the battle.
What’s Inside the Formula?
Each serving is stacked with:
🔹 High-quality proteins
🔹 A serious dose of clean carbs & healthy fats
🔹 Essential amino acids
🔹 Creatine monohydrate
This combination fuels faster muscle recovery, consistent strength gains, and serious weight gain — the right way.
Performance Benefits
Here’s what stood out from my experience:
Creatine added a noticeable edge in strength
🍽️ Hitting calorie goals became easy
Recovery between workouts improved big time
This shake helps you train harder, recover faster, and build size without the fluff.
Final Thoughts
USN Hyperbolic Mass is perfect if you’re aiming to:
✅ Bulk up consistently
✅ Boost your gym performance
✅ Recover like a pro
✅ Enjoy your shake, not just tolerate it
It’s a solid, all-around gainer that delivers results and actually tastes amazing.
👉 Read our full USN Hyperbolic Mass Review for ingredients, results, and who it’s best for.
Critical Mass Original 6kg Review
(25 Servings | Over 900 Calories Per Serving)
Struggling to gain weight no matter how much you eat?
Critical Mass Original is here to flip the script for all you hard gainers out there.
Who’s It For?
This one’s designed specifically for:
✔️ Skinny guys with fast metabolisms
✔️ Bodybuilders, lifters, and athletes who need serious calories
✔️ Anyone trying to break through a weight plateau
If your body burns through food like a furnace, this calorie-dense shake is your muscle-building ally.
What Makes It Powerful?
Each massive 240g serving packs:
Over 900 calories
55g of premium dairy protein
A balanced blend of carbs, fats, and amino acids
Added L-Glutamine and CLA
Digestive enzyme Bromelain for easy absorption
Naturally high in BCAAs and EAAs
You’re not just getting calories — you’re getting clean, muscle-fueling nutrients your body can actually use.
Flavour Game & Mixability
With 6 delicious options including:
Chocolate
Strawberry
Cookies ‘N’ Cream
White Choco Bueno
Banana
Vanilla
…you’re covered no matter your taste.
Plus, it mixes smoothly in a shaker, no clumps, and goes down easy with milk or water.
What I Noticed
From personal experience:
✅ Recovery got quicker
✅ Strength improved session after session
✅ Calories were easy to hit, even on rest days
✅ The added creatine-like boost from MCTs, flaxseed oil, and glutamine made workouts feel stronger
This is a real mass-building formula — not just empty calories.
Final Thoughts
If you’re serious about bulking and tired of spinning your wheels with low-calorie shakes, Critical Mass Original is one of the best full-package gainers on the market.
✅ High-quality ingredients
✅ Huge calorie boost
✅ Tastes amazing
✅ Trusted for serious results
Highly recommended for anyone who wants to pack on size without messing around.
Mass Gainers Defined
Mass gainers are high-calorie supplements that will help you achieve the required calorie excess for muscle building. Containing a potent blend of macro- and micro-nutrients, they support heavy training sessions, lightning quick recoveries, and restoration of the muscles. Gaining your desirable form as a naturally lean individual is not exactly an easy task—let alone when your body needs more calories that you can easily ingest.
Top-Rated Selection
Our experts have assessed and handpicked the finest mass gainers and weight gainers from the best protein brands such as Mutant Mass Extreme, USN, Optimum Nutrition, and numerous others. What we pay attention to are:
Quality & Efficacy: Supplements made with the best ingredients for massive muscle gains.
Taste & Consistency: Delicious flavors for enjoyable and convenient shake time.
Value for Money: Good performance at reasonable costs that don’t sacrifice nutrition value.
Balanced Macronutrients: Best blend of protein, quality complex carbohydrates and good fats to fuel muscle recovery and build-up.
Among the best mass and weight gainers for skinny guys are the products below—designed to deliver one serious nutritional wallop when your nutrition for the day is not quite up to par.
Why Mass Gainers are Indispensable for Skinny Guys
Muscle-building as a leaner implies always having more calories into you than you are expending. Mass gainers offer:
High-Calorie Nutrition: Ready-to-drink nutrition or powdered drinks with 500–1000+ calories per serving enable you to create the needed calorie surplus.
Balanced Macronutrients: High-quality proteins balanced carefully with complex carbohydrates and healthy fats for support for muscle-building and recovery.
Convenience: Preparing a shake ahead of or after one’s workout with little time consumed on preparing an entire meal—is ideally suited to busy lives.
What to Look For When Choosing Mass Gainers UK
When choosing the right mass gainer for skinny guys aiming for rapid muscle growth, consider these critical factors:
✅ Calorie Density
High-Calorie Formula: Look for products with high calorie per serving content. This bridges the calorie deficit and enables maintaining the surplus more readily.
✅ Protein Content
Quality Protein Blend: Consider mass gainers with more than 20–30 grams of protein per serving. Protein is required to build and repair muscle tissues after tough exercises.
✅ Carbohydrate and Fat Profile
Complex Carbs: Choose products with carbohydrate-based nutrition that fuel your training periods and support recovery rather than spiking your bloodstream.
Healthy Fats: Select good sources of unsaturated fats that are good for the overall health and hormone production and avoid foods with high saturated or trans fat content.
✅ Added Nutrients
Vitamins and Minerals: High-calorie mass gainers are often supplemented with extra vitamins and minerals such that your body receives the necessary micronutrients when you are on high-calorie diets.
Top Strategies for Using Mass Gainers Effectively
Meal Timing: Add your mass gainer at around workout times. Pre-workout can give you energy with a shake, and post-workout can help initiate muscle recuperation with a shake.
Liquid Base: To get a creamier texture as well as additional calories, blend your mass gainer with milk as opposed to water.
Consistency is the Key: Supplement your meals with your mass gainer regularly. Consistency, along with proper nutrition and regular training, gets the best muscle-building outcome.
Monitor Progression: Track your caloric intake, output of your training, and body composition changes to adjust your supplementation accordingly.
Mass Gainer vs Weight Gainer
Although the terms are often used interchangeably, mass gainers and weight gainers are not the same — and choosing the right one matters if you want muscle, not just scale weight.
Weight Gainers (Fast Size & Bodyweight)
Weight gainers are designed primarily to increase total bodyweight as quickly as possible.
Typical features:
Very high calories (800–1,200+ kcal per serving)
Extremely high carbohydrates
Lower protein relative to calories
Faster weight gain (may include fat)
Best for:
Extremely skinny hardgainers
Fast metabolisms struggling to gain any weight
Short-term size pushes when calories are impossible to hit
Mass Gainers (Muscle-Focused Growth)
Mass gainers are formulated to support lean muscle growth with controlled calories.
Typical features:
Moderate to high calories (300–700 kcal per serving)
Higher protein content (30–50g)
Balanced carbs and healthy fats
Often include creatine and amino acids
Best for:
Skinny guys lifting weights consistently
Lean bulking phases
Long-term muscle and strength development
Which Is Better for Skinny Guys?
For most skinny guys who train regularly, mass gainers are the better long-term choice because they support muscle growth without excessive fat gain.
Use a weight gainer if:
You genuinely cannot gain weight at all
Your appetite is extremely low
You need rapid calorie intake
Use a mass gainer if:
You want lean muscle growth
You’re training 3–5x per week
You want sustainable, controllable gains
💡 Expert Tip:
Many skinny guys start with a mass gainer and only move to a weight gainer if progress stalls — not the other way around.
Full Guide on the Best Weight Gain Supplements
Need more help with your supplement selection, use our full guide here to find all the help and how to use them for weight and muscle gain.
Best Mass Gainers – Final Advice & Next Steps
Choosing the right mass gainer is only one part of the equation. To actually gain weight and build muscle as a skinny guy, your supplement choice must be combined with the right training plan, calorie intake, and consistency.
If you’re still struggling to move the scale, make sure you’ve covered these fundamentals:
🔹 Train for Growth, Not Just Sweat
Mass gainers work best when paired with progressive overload training. If your weights aren’t increasing over time, your calories won’t turn into muscle.
👉 Follow our proven Beginner Workout Plan for Skinny Guys to ensure your training supports real size and strength gains.
🔹 Understand When to Use a Mass Gainer vs Whey
Not every skinny guy needs extreme calories all the time. Some benefit more from combining whey protein with creatine, while others need a full mass gainer daily.
👉 Read our full breakdown: Whey Protein vs Mass Gainer – Which One Is Better?
🔹 Stack Smart for Faster Results
For best results, many skinny guys combine:
A mass gainer (post-workout or between meals)
Creatine for strength progression
Whey protein to support daily protein targets
👉 See our expert picks in the Best Creatine Supplements for Muscle Gain guide.
🔹 Don’t Ignore Diet & Consistency
Even the best mass gainer won’t work if it’s used inconsistently or without enough total calories across the day.
👉 Learn how to structure your intake properly in our How to Gain Weight Fast for Skinny Guys complete guide.
Final Word – choode the Right Mass Gainer for You
If gaining weight has always felt impossible, mass gainers remove the biggest barrier: hitting a calorie surplus every single day.
Pick the gainer that fits your metabolism, follow a structured training plan, stay consistent, and your body will respond.
Now let’s answer the most common questions skinny guys have about mass gainers 👇
Frequently asked questions
The top picks for mass and weight gainers: Mutant Mass Extreme 2500, Optimum Nutrition Serious Mass, USN Muscle Fuel Anabolic, USN Hyperbolic Mass.
When selecting a mass gainer, consider factors such as your metabolism, calorie requirements, and desired rate of weight gain. For fast metabolisms, opt for products like Mutant Mass Extreme 2500 or USN Hyperbolic Mass, while those with slower metabolisms may prefer options like Optimum Nutrition Serious Mass.
Yes, mass gainers can be beneficial for beginners looking to build muscle and increase weight rapidly. They provide a convenient way to boost calorie intake and support muscle growth.
To use a mass gainer effectively, determine your calorie and nutrient requirements based on your fitness goals and metabolism. Incorporate mass gainer shakes into your daily nutrition plan, consuming them between meals or immediately after workouts to support muscle recovery and growth.
Mass gainers are specifically formulated to provide a high calorie and nutrient-dense option for individuals looking to gain weight and build muscle. They contain a balanced mix of proteins, carbohydrates, and fats, making them ideal for supporting muscle growth and recovery.
Mass gainers work by providing the body with a surplus of calories and essential nutrients, creating an optimal environment for muscle growth and recovery. They capitalize on the body’s anabolic state post-exercise, helping to replenish nutrient stores and promote muscle repair.
Yes, mass gainers are particularly beneficial for skinny guys and hard gainers who struggle to consume enough calories through their regular diet alone. These products provide a convenient way to increase calorie intake and support muscle growth.
While both mass gainers and weight gainers aim to promote weight and muscle gain, they differ in their macro-nutrient compositions and calorie contents. Mass gainers typically contain a balanced ratio of proteins, carbohydrates, and fats, whereas weight gainers focus more on providing a high-calorie option with a higher proportion of carbohydrates.
Our quick list of the best mass gainers in the uk: 1. Mutant Mass Extreme 2. Usn Hyperbolic Mass 3. Usn Muscle Fuel Anabolic 4. Warrior Lean Mass Gainer 5. Optimum Nutrition Serious Mass 6. Applied Nutrition Critical Mass 7. CNP Mass XL.
The best mass gainer for skinny guys in the uk is Usn Hyperbolic mass. A complete formula to add muscle and gainer weight.
