MASS gainers
Applied Nutrition Critical Mass Professional 6kg
Original price was: £65.99.£57.99Current price is: £57.99.
Best Mass Gainers Uk: Complete Guide
Gaining weight as a skinny guy can be frustrating. You eat constantly, train hard—but the scale barely moves. That’s where mass gainers come in.
These high-calorie protein shakes are made for hard gainers with fast metabolisms. They pack in the protein, carbs, and calories your body needs to build muscle and size—without constantly force-feeding yourself.
In this complete UK guide, we review the best mass gainers for skinny guys, covering top brands like Mutant Mass, Serious Mass, and Applied Nutrition. Whether you’re looking to gain weight fast, build lean muscle, or bulk on a budget, we’ve got you covered.
👉 Also see our Beginner Workout Plan for Skinny Guys to maximise your gains with these supplements.
What Are the Best Mass Gainers for Skinny Guys & How Do They Work?
A mass gainer (or weight gainer) is a high-calorie protein supplement designed to help individuals struggling to gain weight increase muscle mass quickly. They contain a mix of protein, carbohydrates, and healthy fats, making them ideal for hard gainers who need extra calories.
How to Choose the Best Mass Gainer for Your Body Type
✅ Fast Metabolism? Choose high-calorie mass gainers to fuel rapid weight gain.
✅ Slower Metabolism? Opt for lower-calorie, nutrient-dense weight gainers to build muscle while staying lean.
✅ Struggling to eat enough? A weight gainer shake helps you hit your daily calorie target without force-feeding yourself.
Best Mass Gainer for Skinny Guys (with Fast Metabolisms)
If you’re a hard gainer who struggles to put on weight, these high-calorie mass gainers will help you bulk up fast:
1. Mutant Mass Extreme – Best Overall Mass Gainer for Skinny Guys
Why it’s the best: Mutant Mass Extreme delivers a perfect blend of protein, carbs, and essential fats, packing a high-calorie punch to fuel serious muscle growth.
💪 Best for:
✔ Hard gainers needing rapid weight gain
✔ Mixing with Mutant Creakong CX8 for even better results
2. Applied Nutrition Critical Mass Original – High-Calorie Weight Gainer
💥 Key Benefits: A powerful muscle-building and weight-gain formula loaded with essential nutrients.
✅ Boost results with: Applied Nutrition Creatine to increase strength and maximize muscle growth.
3. USN Hyperbolic Mass – Ideal for Muscle Size & Strength
Why Choose It? Designed for fast metabolisms, USN Hyperbolic Mass contains added creatine to fuel intense workouts and maximize muscle size.
Best Weight Gainer for Skinny Guys (with Slower Metabolism)
For those who gain weight more easily but still want quality muscle growth, these lean mass gainers are the best options:
1. USN Muscle Fuel Anabolic – Best Lean Mass Gainer
Why it works: A low-calorie, nutrient-dense mass gainer that helps build muscle without excessive fat gain.
✅ Perfect for:
✔ Gradual weight gain without losing definition
✔ A complete meal replacement for muscle recovery
2. Optimum Nutrition Serious Mass – High-Calorie Mass Gainer
💪 Key Features: A calorie-dense formula designed for serious bulking.
🚀 Tip: If you’re worried about gaining weight too quickly, reduce the serving size to control calorie intake.
Fast vs. Controlled Weight Gain – Which Strategy is Best for You?
Fast Weight Gain & Muscle Growth
If you want to pack on size quickly, go for a high-calorie weight gainer like:
✔ Serious Mass
✔ Mutant Mass & Mutant mass Extreme
✔ Critical Mass
➡ Pro Tip: Drink your protein shake immediately after a workout to prevent muscle breakdown and accelerate gains.
Gradual Muscle Gain & Lean Physique
If you prefer a controlled weight gain approach, try:
✔ USN Muscle Fuel Anabolic
✔ A combination of Whey Protein + Creatine
➡ Alternative: Not a fan of weight gainers? Add a BCAA or Amino drink in the morning and around workouts to prevent muscle breakdown and support lean growth.
Which Mass Gainer Should You Choose?
If you’re a skinny guy looking to gain weight and build muscle, mass gainers are an easy way to increase calorie intake and support muscle recovery.Top Picks for Skinny Guys:
🏆 Best Overall Mass Gainer: Mutant Mass Extreme
💥 Best for Maximum Muscle Size: USN Hyperbolic Mass
💪 Best for Lean Mass & Definition: USN Muscle Fuel Anabolic
🚀 Best Budget-Friendly Option: Applied Nutrition Critical Mass Original
All of these mass gainers mix well, taste great, and suit different budgets.
✔ Pick the one that aligns with your weight gain goals and start making real muscle gains today!
Understanding Mass Gainers
Mass gainers are high-calorie supplements designed to help you create the calorie surplus needed for muscle growth. They provide a potent blend of macro- and micro-nutrients to support intense training sessions, speedy recovery, and muscle repair. Achieving your dream physique as a naturally lean individual is no small feat—especially when your body demands more calories than you can easily consume.
Expert-Approved Selection
Our experts have analyzed and handpicked the finest mass gainers and weight gainers from leading protein brands such as Mutant Mass Extreme, USN, Optimum Nutrition, and more. We consider factors such as:
- Quality & Effectiveness: Only products made with premium ingredients that drive impressive muscle gains.
- Taste & Consistency: Delicious flavors that make shake time enjoyable and hassle-free.
- Value for Money: Affordable options that perform without compromising nutritional benefit.
- Balanced Macronutrients: The perfect mix of protein, complex carbohydrates, and healthy fats to fuel muscle recovery and growth.
For skinny guys, these products are among the best mass and weight gainers for skinny guys—designed to deliver a substantial nutritional punch even when your daily food intake falls short.
Why Mass Gainers Are Essential for Skinny Guys
Building muscle as a lean individual requires consistently eating more calories than you expend. Mass gainers offer:
- High-Calorie Nutrition: Ready-to-drink shakes or powders packed with 500–1000+ calories per serving help you create the necessary calorie surplus.
- Balanced Macronutrients: A thoughtful blend of high-quality proteins, complex carbs, and healthy fats to aid in recovery and muscle growth.
- Convenience: Easily mix up a shake pre- or post-workout without having to spend time preparing a full meal—ideal for busy lifestyles.
What to Look For in Mass Gainers UK
When choosing the right mass gainer, especially if you’re a skinny guy aiming for rapid muscle growth, consider these critical factors:
Calorie Density
- High-Calorie Formula: Look for products that provide a significant number of calories per serving. This bridges the calorie gap and makes it easier to sustain a surplus.
Protein Content
- Quality Protein Blend: Aim for mass gainers boasting at least 20–30 grams of protein per serving. Protein is essential for repairing and building muscle after intensive workouts.
Carbohydrate and Fat Profile
- Complex Carbs: Choose products with nutrient-dense carbohydrates that fuel your workouts and support recovery without causing blood sugar spikes.
- Healthy Fats: Opt for sources of unsaturated fats that support overall health and hormone production while avoiding products high in saturated or trans fats.
Added Nutrients
- Vitamins and Minerals: Superior mass gainers are often fortified with extra vitamins and minerals, ensuring your body receives the essential micronutrients it needs when consuming higher-calorie diets.
Top Tips for Using Mass Gainers Effectively
- Meal Timing: Incorporate your mass gainer around workouts. A shake before training can provide energy, while a post-workout shake helps kickstart muscle recovery.
- Liquid Base: For a creamier consistency and added calories, mix your mass gainer with milk instead of water.
- Consistency is Key: Use your mass gainer as a supplement to regular meals. Consistent use, combined with a balanced diet and regular training, yields the best muscle-building results.
- Monitor Progress: Track your calorie intake, training output, and body composition changes to adjust your supplementation as needed.
Best Weight & Mass Gainers in the UK – Reviews & Top Picks (2025)
💥 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.
🏆 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. 💥
🥇 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. 👊
🚀 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.
🏋️♂️ 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.
🥊 Weight Gainers vs Mass Gainers: What’s the Difference & Which Is Right for You?
In the world of muscle building supplements, two names often come up: weight gainers and mass gainers. While many people use these terms interchangeably, there are important differences between them.
If you’re a skinny guy trying to gain weight or build lean muscle, understanding how each one works will help you choose the right supplement to match your goals.
🏋️♂️ What Are Weight Gainers?
Weight gainers are high-calorie shakes made for people who struggle to eat enough during the day. They help you increase your overall body weight—not just muscle.
🔍 Key Features of Weight Gainers:
Very High Calories: Usually between 500–1,200+ calories per serving
High in Carbs: Focused on carbs (often 100–200g) with lower protein (15–25g)
Fast Weight Gain: Ideal for quick size increases, but may include some fat gain
Designed For: Hardgainers with a fast metabolism or low appetite
What does a weight gainer do?
A weight gainer is a high-calorie supplement designed to help individuals rapidly increase their overall body weight by providing large amounts of carbohydrates and calories in one serving.
💪 What Are Mass Gainers?
Mass gainers are more balanced in nutrients and are aimed at supporting lean muscle growth rather than just adding size. They include more protein and healthier macros overall.
🔍 Key Features of Mass Gainers:
Moderate to High Calories: Around 300–700 calories per serving
Higher Protein: Typically 30–50g protein per serving
Balanced Carbs & Fats: Lower carb content than weight gainers, includes healthy fats
Designed For: Skinny guys who want to gain muscle without excessive fat
What is the difference between a mass gainer and a weight gainer?
Mass gainers are designed to support lean muscle growth with higher protein and balanced macros, while weight gainers are higher in calories and carbs to help increase overall body weight quickly.
🧪 Nutritional Differences at a Glance
When comparing weight gainers and mass gainers, the most noticeable difference lies in their nutritional makeup and purpose. Weight gainers typically contain between 500 to 1,200+ calories per serving, with a relatively low protein content of 15–25 grams, but are packed with high amounts of carbohydrates, often exceeding 100 grams.
The fat content can vary depending on the brand, but the primary focus is delivering a large calorie surplus to promote rapid weight gain—making them ideal for individuals who struggle to gain weight or have a fast metabolism.
In contrast, mass gainers are formulated to support lean muscle growth. They generally provide a more moderate calorie range of 300 to 700 per serving, but with a higher protein content of 30–50 grams. Their carbohydrate content is moderate, and they often include healthy fats to support balanced energy release and muscle recovery.
This makes mass gainers a better choice for those aiming for steady, controlled gains without excessive fat accumulation.
Use a weight gainer if you need to increase total weight fast
Use a mass gainer if you want to build muscle and stay lean
⏱️ When Should You Take Them?
Knowing the best time to take these supplements can make a big difference in your results.
📅 Weight Gainer Timing:
Between meals or before bed to boost daily calories
Pre-workout if you’re training with low energy
Good as a meal replacement if you’re skipping meals
📅 Mass Gainer Timing:
Post-workout to help muscle recovery and glycogen replenishment
As a high-protein snack during the day
Ideal for a clean bulk strategy
🧠 Final Thoughts: Which One Should You Choose?
Your supplement choice should match your fitness goal:
💥 Choose a Weight Gainer if:
You’re underweight or a “hardgainer”
You burn calories fast and struggle to eat enough
You want to gain size quickly, even if it includes some fat
🔧 Choose a Mass Gainer if:
You want to gain lean muscle, not just weight
You’re training consistently with weights
You prefer a balanced, clean bulk with less fat gain
Should skinny guys take a weight gainer or mass gainer?
Skinny guys can benefit from both, but weight gainers are ideal for those who struggle to eat enough and need fast weight gain, while mass gainers are better for building lean muscle with a controlled calorie surplus.
🎯 Pro Tip:
If you’re just starting out, go with a mass gainer to build quality muscle. Only move to a weight gainer if you’re still not seeing results after hitting your protein and calorie goals with regular food and shakes.
Full Guide on the Best Weight Gain Supplements for skinny Guys
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.
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, and CNP Mass XL.
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 Mutant Mass Extreme 2500. It offers over 1,000 calories per serving, 30+ grams of protein, and fast-digesting carbs—ideal for hard gainers who struggle to gain size through food alone.
