MASS gainers
Applied Nutrition Critical Mass Professional 6kg
Best Mass Gainer UK for Skinny Guys: Complete Guide to Weight Gain
Struggling to gain weight no matter how much you eat or train? If you’re a skinny guy with a fast metabolism, gaining size can feel impossible. That’s where a mass gainer comes in.
In this guide, we highlight the best mass gainers in the UK for skinny guys—specifically designed to help hard gainers build serious size, strength, and lean muscle. These high-calorie shakes deliver the protein, carbs, and nutrients your body needs to bulk up and recover fast.
Whether you’re after the best weight gainer for skinny guys, a budget option, or a leaner shake—we’ve got you covered.
👉 Also check out our Beginner Workout Plan for Skinny Guys to maximise your gains with these supplements.
What Is the Best Mass Gainer for Skinny Guys in the UK?
A mass gainer (also called a weight gainer) is a high-calorie supplement created to help skinny guys who struggle to gain weight. Packed with protein, carbs, and healthy fats, these shakes make it easier to eat in a calorie surplus and support muscle growth.
✅ Key Benefits:
Convenient and calorie-dense
Supports faster muscle and weight gain
Reduces the need for constant eating
Often includes creatine, amino acids, and vitamins
How to Choose the Right Weight Gainer for Skinny Guys
Consider your body type and goals:
✅ Fast metabolism? Choose a high-calorie mass gainer for rapid size gains.
✅ Slower metabolism? Pick a leaner gainer to bulk up while staying defined.
✅ Struggling to eat enough? A weight gainer shake helps you reach your calorie target with ease.
Top 3 Best Mass Gainers for Skinny Guys in the UK
1. Mutant Mass Extreme – Best Overall Mass Gainer for Skinny Guys
A calorie-loaded powerhouse designed to fuel rapid growth in hard gainers.
Why we recommend it:
✔ Over 1000 calories per serving
✔ Perfect for skinny guys with fast metabolisms
✔ Excellent when stacked with Mutant Creakong CX8
2. Applied Nutrition Critical Mass – Best Budget Mass Gainer UK for Skinny Guys
A UK-made, budget-friendly formula that doesn’t skimp on nutrition or results.
Key Features:
✔ High in calories and protein
✔ Includes oats and MCTs for slow-release energy
✔ Combine with Applied Nutrition Creatine for enhanced strength
3. USN Hyperbolic Mass – Best Weight Gainer for Skinny Guys Focused on Size & Strength
Formulated to support explosive muscle gains for skinny guys training hard.
Why it works:
✔ High-calorie formula with added creatine
✔ Supports muscle recovery and strength
✔ Built for intense training sessions
Best Lean Mass Gainers for Skinny Guys Who Want Definition
If you’re a skinny guy who gains fat easily or prefers a cleaner bulk, these leaner options are your best bet:
1. USN Muscle Fuel Anabolic – Best Lean Mass Gainer for Skinny Guys
Helps build lean mass gradually while maintaining muscle definition.
Top Benefits:
✔ Balanced calorie-to-protein ratio
✔ Works as a meal replacement or post-workout shake
✔ Promotes lean muscle recovery and growth
2. Optimum Nutrition Serious Mass – High-Calorie Gainer for Skinny Guys
A go-to for skinny guys wanting serious size gains without breaking the bank.
Tip: Start with half a serving if you’re concerned about gaining fat too quickly.
Fast vs. Controlled Weight Gain: What’s Right for Skinny Guys?
Fast Muscle Growth (High-Calorie Mass Gainers)
Choose if: You want to gain mass quickly and have a fast metabolism.
Top Picks for Skinny Guys:
✔ Mutant Mass Extreme
✔ Serious Mass
✔ Critical Mass
💡 Pro Tip: Drink your shake right after workouts to maximise recovery and growth.
Gradual Weight Gain & Lean Muscle
Choose if: You want steady muscle gains while staying lean and defined.
Best Options for Skinny Guys:
✔ USN Muscle Fuel Anabolic
✔ Whey Protein + Creatine stack
💪 Bonus Tip: Add a BCAA or amino drink around your workouts to preserve muscle and improve recovery.
Which Is the Best Mass Gainer UK for Skinny Guys?
If you’re a skinny guy ready to put on healthy weight and real muscle, these UK mass gainers are your shortcut to effective bulking.
🏆 Top Recommendations:
Best Mass Gainer for Skinny Guys Overall: Mutant Mass Extreme
Best for Size and Strength: USN Hyperbolic Mass
Best for Lean Gains: USN Muscle Fuel Anabolic
Best Budget Option: Applied Nutrition Critical Mass
All of these shake options taste great, mix well, and suit different goals and budgets.
👉 Pick the one that fits your needs—and start packing on real muscle today.
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.
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.
Weight Gainers vs Mass Gainers: What’s the Difference & Which Is Right for You?
Among the many muscle-building supplements on the market today, two names are routinely brought up: weight gainers and mass gainers. While many confuse the two with one another, there are justifiable differences between the two.
If you are a lean person wishing to bulk up or gain lean muscle mass, understanding the mechanism of action for each will help you to determine the right supplement for you.
What Are Weight Gainers?
Weight gainers are high-calorie shakes for individuals with trouble ingesting enough during the day. Weight gainers will contribute to your entire body weight—not just muscle mass.
Principal Features of Weight Gainers:
Very High Calories: Generally between 500–1,200+ calories per serving
High Carb: Centered around carbs (usually 100–200g) with reduced protein (15–25g)
Fast Weight Gain: Most suitable for quick gains in size, but may incur some gains of fat
Specifically Designed For: Hardgainers with fast metabolism or poor appetite
What is the job of a weight gainer?
A weight gainer is one of the best weight gain supplements available on the market today to rapidly achieve weight gain by giving high numbers of carbohydrate and calorie per serving.
What Are Mass Gainers?
Mass gainers are nutritionally more balanced and are formulated for lean muscle gains instead of size gains. There is more protein and better overall macros present in the mass gainers.
Main Features of Mass Gainers:
Moderate to High Calories: about 300–700 calories per serving
Increased Protein: Typically 30–50g protein per serving
Balanced Carbs & Fats: Lower level of carbs relative to weight gainers, includes healthy fats
Recommended For: Skinny guys seeking to build muscle mass with minimal fat
What is the difference between a weight gainer and a mass gainer?
Mass gainers are formulated to support lean muscle gains with higher protein and balanced macros, whereas weight gainers are higher-caloric and carbohydrate-based products to support quick gains in overall body weight.
Comparative Nutrition at a Glance
In comparisons between weight gainers and mass gainers, the most noticeable difference is between their constitution and their planned use of nutrition.
Weight gainers will contain approximately 500 to 1,200+ calories per scoop with relatively low protein content of 15–25 grams but are packed with elevated carbohydrate content usually over 100 grams.
The fat content is regulated by the brand but the chief issue is to help with the high calorie surplus for rapid weight gain—good for those with difficulty gaining weight or with a fast metabolism.
Mass gain supplements are not formulated to build lean muscles. These have a relatively more balanced calorie level between 300 to 700 per scoop but are more in protein by about 30–50 grams. Carbs are balanced as well, and they are usually fortified with good fats for balanced energy output and post-workout muscle recovery.
✅ This is why mass gainers are better suited for skinny guys with the objective of making steady, controlled gains with minimal fat retention.
✅ Summary
Use a weight gainer when one needs to gain weight rapidly
Make use of a mass gainer when you want to build muscle and stay lean
When Should You Take Them?
It is important to know the optimal time to take the supplements as it will greatly affect the results.
⏱️ Weight Gainer Timing:
In between meals or at bedtime to increase overall daily calories
Pre-workout if you are working with low energy
Good as a substitute for meals when skipping food
⏱️ Mass Gainer Timing:
Post-workout to support muscle recuperation and glycogen restoration
As a high-protein afternoon snack
Ideal for a clean bulk phase
Final Thoughts: Which One Should You Choose?
Your supplement choice should match your fitness goal:
Choose a Weight Gainer if:
You’re a “hardgainer”
You metabolize calories quickly and struggle to eat enough
You want to add size quickly, even if it includes some fat
Choose a Mass Gainer if:
You are aiming to create lean muscle, not just gain weight
You’re exercising routinely with weights
You prefer a balanced, lean bulk with minimal fat gain
Do Skinny Guys Need a Weight Gainer or Mass Gainer?
Both are good for skinny guys, but:
Weight gainers are optimal for those with difficulty consuming enough and who need rapid weight gain
Mass gainers are better for lean muscle with controlled calorie excess
💡 Pro Tip:
If you are new to this, take a mass gainer to build quality muscle. Switch to a weight gainer only when you are not gaining despite having achieved your protein and calorie requirements through whole foods 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.
