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Muscle Gain

Collection: Muscle Gain

Build size, strength and lean muscle with our premium muscle gain supplements at The Box Supplements. Whether you're looking for high-quality whey protein, mass gainers, creatine or intra-workout support, we stock trusted brands to help maximise muscle growth and recovery. Ideal for beginners and advanced lifters alike, our muscle-building range is designed to support progressive overload, improved recovery and consistent results. Shop muscle gain supplements in the UK with fast delivery and outstanding customer service.

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1792 products

Applied Nutrition Beef Mass Gainer 3.13kg Tropical Vibes

Applied Nutrition Beef Mass Gainer 3.13kg Tropical Vibes

Regular price £45.99
Sale price £45.99 Regular price
Sci-MX V-Gain 2.2kg Chocolate

Sci-MX V-Gain 2.2kg Chocolate

Regular price £32.99
Sale price £32.99 Regular price
Applied Nutrition Critical Mass Original 6kg Strawberry

Applied Nutrition Critical Mass Original 6kg Strawberry

Regular price £42.99
Sale price £42.99 Regular price
Applied Nutrition Critical Mass Original 6kg Banana

Applied Nutrition Critical Mass Original 6kg Banana

Regular price £42.99
Sale price £42.99 Regular price
Warrior Lean Mass Gainer 5040g - Salted Caramel

Warrior Lean Mass Gainer 5040g - Salted Caramel

Regular price £42.99
Sale price £42.99 Regular price
Warrior Lean Mass Gainer 5040g - Double Chocolate

Warrior Lean Mass Gainer 5040g - Double Chocolate

Regular price £42.99
Sale price £42.99 Regular price
Warrior Lean Mass Gainer 5040g - Banana

Warrior Lean Mass Gainer 5040g - Banana

Regular price £42.99
Sale price £42.99 Regular price
USN Wholefood Gainer 2kg - Vanilla

USN Wholefood Gainer 2kg - Vanilla

Regular price £30.99
Sale price £30.99 Regular price
USN Hyperbolic Mass 2kg - French Vanilla

USN Hyperbolic Mass 2kg - French Vanilla

Regular price £28.99
Sale price £28.99 Regular price
Reflex Nutrition One Stop Xtreme 4.35kg - Vanilla

Reflex Nutrition One Stop Xtreme 4.35kg - Vanilla

Regular price £69.99
Sale price £69.99 Regular price
DY Nutrition Shadowhey Isolate 2kg - Vanilla Caramel

DY Nutrition Shadowhey Isolate 2kg - Vanilla Caramel

Regular price £76.99
Sale price £76.99 Regular price
Applied Nutrition Iso-XP 1.8kg - Mango Passion Fruit

Applied Nutrition Iso-XP 1.8kg - Mango Passion Fruit

Regular price £82.99
Sale price £82.99 Regular price
Optimum Nutrition Serious Mass 5.45kg - Chocolate Peanut Butter

Optimum Nutrition Serious Mass 5.45kg - Chocolate Peanut Butter

Regular price £62.99
Sale price £62.99 Regular price
Optimum Nutrition Serious Mass 2.73kg - Strawberry

Optimum Nutrition Serious Mass 2.73kg - Strawberry

Regular price £38.99
Sale price £38.99 Regular price
Optimum Nutrition Serious Mass 2.73kg - Chocolate Peanut Butter

Optimum Nutrition Serious Mass 2.73kg - Chocolate Peanut Butter

Regular price £38.99
Sale price £38.99 Regular price
Optimum Nutrition Serious Mass 2.73kg - Banana

Optimum Nutrition Serious Mass 2.73kg - Banana

Regular price £38.99
Sale price £38.99 Regular price
NutriSport Weight Gain 700g - Strawberry

NutriSport Weight Gain 700g - Strawberry

Regular price £11.99
Sale price £11.99 Regular price
NutriSport Weight Gain 5kg - Strawberry

NutriSport Weight Gain 5kg - Strawberry

Regular price £38.99
Sale price £38.99 Regular price
NutriSport Weight Gain 5kg - Chocolate

NutriSport Weight Gain 5kg - Chocolate

Regular price £38.99
Sale price £38.99 Regular price
NutriSport Protein + Carbs 5kg - Banana

NutriSport Protein + Carbs 5kg - Banana

Regular price £38.99
Sale price £38.99 Regular price

FAQ's

How long will delivery take?

We ship via DPD Next Working Day for orders placed before 3pm. Please allow 1 working day for order handling and dispatch, plus 1 working day transit.

How long do I have to return an item?

You have 30 days from the date you receive your order to return any items.

What happens if I order after the 3pm cut-off?

Orders placed after 3pm will enter our handling queue the next working day, and you’ll then need 1 working day for processing plus the usual 1 working day for DPD delivery.

How do I start a return?

Simply fill out the Customer Returns Form and we’ll send you the return instructions.