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PRODUCT INFORMATION

Instant Mass® Heavyweight provides the body with protein from Whey Protein Concentrate, Micellar Casein, Native Whey, Hydrolysed Whey Protein

The whey protein concentrate in Instant Mass® Heavyweight is made by separating the whey protein from the other components in milk. Hydrolysed whey protein is treated with enzymes to make it even faster to digest.

This product will feed the body energy, while the carbohydrates provide a long-lasting comprehensive energy source to enable the body to work out for longer, more intense periods.

HOW TO USE

5.4kg size: Mix 300g (approximately two level 250ml measures (there is a scoop included in the bag) with 700ml water in a shaker or blender.

2kg size: Mix 300g (approximately five level 60ml measures (there is a scoop included in the tub) with 700ml water in a shaker or blender.

When just starting with this product, you may find it beneficial to begin with half the quantity before slowly increasing to the full serving in order to make it fit into your personal calorie plan.

Consume Instant Mass® Heavyweight between meals to maintain a positive nitrogen balance, or drink 20-30 minutes after a workout for optimal results. Alternatively, take Instant Mass® Heavyweight 45-60 minutes before bed to contribute to muscle maintenance overnight.

Once mixed, consume the shake immediately and don't leave to stand.

For a shake that is more calorie-heavy and creamier, try the product with semi-skimmed milk.

Protein contributes to the growth and maintenance of muscle mass.

Creatine increases physical performance in successive bursts of short-term, high intensity exercise. The beneficial effect is obtained with a daily intake of 3 g of creatine.

This product is a food supplement and should be used in conjunction with food as part of a varied and balanced diet and healthy lifestyle, not as a substitute for such. Recommended consumption is one 300 g serving per day. Do not exceed the stated recommended daily dose. This product is not intended for use by persons under the age of 18. Keep out of reach of young children.

DELIVERY & RETURNS

Free Standard Delivery on UK Orders Over £50.00
UK Standard (5-7 working days) £4.00
UK Next Day Delivery £6.00
Jersey, Guernsey & Isle of Man £16.99
Click here for Delivery Information

Instant Mass® Heavyweight

£36.99

6 servings

£6.16/serving

The ultimate choice for those looking to gain muscle mass and weight.

High protein

Fuel every rep
High calorie

Made to bulk
All in one

Optimised for convenience

Instant Mass® Heavyweight provides the body with protein from Whey Protein Concentrate, Micellar Casein, Native Whey, Hydrolysed Whey Protein

This product will feed the body energy, while the carbohydrates provide a long-lasting comprehensive energy source to enable the body to work out for longer, more intense periods.

CHOOSE BUNDLE

1 tub

— Servings —/serving

🚚 FREE SHIPPING OVER £50

⏱ NEXT DAY UK DELIVERY ORDER BY 13:00

Or express checkout with

PRODUCT INFORMATION

Instant Mass® Heavyweight provides the body with protein from Whey Protein Concentrate, Micellar Casein, Native Whey, Hydrolysed Whey Protein

This product will feed the body energy, while the carbohydrates provide a long-lasting comprehensive energy source to enable the body to work out for longer, more intense periods.

HOW TO USE

DELIVERY & RETURNS

For those who want to gain

For more than 30 years, we’ve built nutritional systems that support your capability for years to come

Grow the way you want

For hard gainers and serious athletes who burn through calories faster than they can consume them, Instant Mass Heavyweight closes the gap, delivering 1,160kcal and 60g of premium blended protein per serving, with no added sugars, corn syrups, or fructose. Every serving is engineered to build mass without compromise.

A DOSE THAT DELIVERS

Good nutrition should make you feel more in control, not more confused. So we keep things clear, using effective ingredients at scientifically-backed doses. Products built to help you stay capable for longer. Because you’ve still got it and we’re here to help you prove it.

QUALITY YOU CAN RELY ON

From our facility in Brighton, we’ve delivered the same high standards for more than two decades. We only believe in the highest grade minerals, so that's what we use.

What's inside

Instant Mass® Heavyweight

PRODUCT INFO

Product Information

Instant Mass® Heavyweight provides the body with protein from Whey Protein Concentrate, Micellar Casein, Native Whey, Hydrolysed Whey Protein

This product will feed the body energy, while the carbohydrates provide a long-lasting comprehensive energy source to enable the body to work out for longer, more intense periods.

Anything else?

Available in a 2kg or 5.4kg bag.

HOW TO USE

Recommended Usage

5.4kg size:Mix 300g (approximately two level 250ml measures (there is a scoop included in the bag) with 700ml water in a shaker or blender.

2kg size:Mix 300g (approximately five level 60ml measures (there is a scoop included in the tub) with 700ml water in a shaker or blender.

When just starting with this product, you may find it beneficial to begin with half the quantity before slowly increasing to the full serving in order to make it fit into your personal calorie plan.

Consume Instant Mass® Heavyweight between meals to maintain a positive nitrogen balance, or drink 20-30 minutes after a workout for optimal results. Alternatively, take Instant Mass® Heavyweight 45-60 minutes before bed to contribute to muscle maintenance overnight.

Once mixed, consume the shake immediately and don't leave to stand.

For a shake that is more calorie-heavy and creamier, try the product with semi-skimmed milk.

Protein contributes to the growth and maintenance of muscle mass.

Creatine increases physical performance in successive bursts of short-term, high intensity exercise. The beneficial effect is obtained with a daily intake of 3 g of creatine.

This product is a food supplement and should be used in conjunction with food as part of a varied and balanced diet and healthy lifestyle, not as a substitute for such. Recommended consumption is one 300 g serving per day. Do not exceed the stated recommended daily dose. This product is not intended for use by persons under the age of 18. Keep out of reach of young children.

NUTRITIONAL INFORMATION

Blueberry

Chocolate Peanut Butter

Chocolate Perfection

Salted Caramel

Instant Mass® Heavyweight

INGREDIENTS

Ingredients

Maltodextrin, Glutamine Peptides (WHEAT), OAT Flour, Whey Protein Concentrate (MILK, Emulsifier (SOYA Lecithin)), Cocoa Powder (Chocolate varieties only), MILK Protein (of which 80% Micellar Casein, 20% Native Whey), Hydrolysed Whey Protein (MILK), Flavourings, Creatine Monohydrate (Creapure®), Sodium Chloride, Cocoa Powder (Salted Caramel variety only), Colour (Betanin) (Strawberries & Cream variety only), Potassium Chloride, Magnesium Citrate, L-Glutamine, L-Choline Bitartrate, Colours (Betanin, Anthocyanins) (Blueberry variety only), Colour (Carotenes) (Vanilla Ice Cream and Salted Caramel varieties only), Vitamin C (L-Ascorbic Acid), Potassium Chloride, Sweetener (Sucralose), Bacillus Coagulans (LactoSpore®), Zinc Bisglycinate, Vitamin E (D-Alpha Tocopherol Acetate), Selenium Enriched Yeast, Ferrous Bisglycinate, Vitamin B3 (Nicotinamide), Copper Bisglycinate, Black Pepper Extract (BioPerine® Piperine), Vitamin A (Retinyl Acetate), Vitamin B5 (Calcium D-Pantothenate), Vitamin D3 (Cholecalciferol), Vitamin B6 (Pyridoxine Hydrochloride), Vitamin B2 (Riboflavin), Vitamin B1 (Thiamine Hydrochloride), Chromium Picolinate, Vitamin B9 (Folic Acid), Vitamin B7 (D-Biotin), Vitamin B12 (Methylcobalamin).
For allergens, including cereals containing gluten, see ingredients in BOLD. May also contain traces of egg.

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Product Comparisons

Protein Source

Serving Size

Protein

Protein %

Fat

Carbohydrate

Sugar

Calories

Instant Mass® Heavyweight

Glutamine Peptides, Whey Protein Concentrate, Milk Protein, Hydrolysed Whey Protein

300g

60g

20%

5.3g

203g

14g

1104kcal

Quick Buy

Instant Mass® Heavyweight

£36.99

6 servings

£6.16/serving

The ultimate choice for those looking to gain muscle mass and weight.

High protein

Fuel every rep
High calorie

Made to bulk
All in one

Optimised for convenience

Instant Mass® Heavyweight provides the body with protein from Whey Protein Concentrate, Micellar Casein, Native Whey, Hydrolysed Whey Protein

This product will feed the body energy, while the carbohydrates provide a long-lasting comprehensive energy source to enable the body to work out for longer, more intense periods.

CHOOSE BUNDLE

1 tub

— Servings —/serving

🚚 FREE SHIPPING OVER £50

⏱ NEXT DAY UK DELIVERY ORDER BY 13:00

Or express checkout with

One Stop® Xtreme

Whey Protein Concentrate, Milk Protein (of which 80% Micellar Casein, 20% Native Whey) & Glutamine Peptides

145g

55g

38%

4.3g

71g

24g

551kcal

Quick Buy

One Stop® Xtreme

£46.49

14 servings

£3.32/serving

Built for serious lifters. Everything you need in one shake, nothing you don't.

High protein

Fuel every rep
All in one

Optimised for convenience

One Stop® Xtreme is Reflex Nutrition's all-in-one muscle-building shake, delivering 55g of grass-fed whey protein, 5,000mg of Creapure® creatine monohydrate, 10.3g of BCAAs and 73g of low GI carbohydrates in every 145g serving. Alongside these core ingredients, each shake includes L-Leucine, Beta Alanine, Betaine Anhydrous, Taurine, DigeZyme® digestive enzyme complex and friendly bacteria, making it one of the most complete and convenient all-in-one training supplements available.

Designed for serious lifters and bodybuilders who want everything in one shake without the need to stack multiple supplements, One Stop® Xtreme is available in six flavours across two tub sizes, 2.03kg and 4.35kg. With a full vitamin and mineral profile and protein sourced from grass-fed cows, it is a premium daily training shake built for those who demand more from their nutrition.

CHOOSE BUNDLE

1 tub

— Servings —/serving

🚚 FREE SHIPPING OVER £50

⏱ NEXT DAY UK DELIVERY ORDER BY 13:00

Or express checkout with

Growth Matrix

Hydrolysed Whey Protein

105g

38g

36%

1.9g

56g

11g

391kcal

Quick Buy

Frequently Asked Questions

What you need to know

Reflex Nutrition Instant Mass Heavyweight is a premium mass gainer shake designed specifically for hard gainers and athletes who train intensely but struggle to consume enough calories and protein through food alone. Each serving provides a high amount of protein, carbohydrates, and calories.

Mix 300g with 700ml of water in a shaker cup or blender and mix until smooth. For precise measurements, using weighing scales is recommended as the scoops measure in millilitres rather than grams. The shake can also be mixed with skimmed milk to increase the calorie and protein content further, depending on your individual goals.

Each 300g serving provides approximately 18 servings from the 5.4kg tub. Instant Mass Heavyweight is also available in a 2kg tub providing approximately 6 serving, a practical option for those trying the product for the first time before committing to the larger size.

Yes, you have the right to cancel your order within 14 days from the date you receive your items, without needing to give a reason.

You have 14 days from the date of delivery to cancel your order under your cooling-off period rights. This allows you to change your mind about your purchase and return the item, provided it is unused and in its original, resellable condition.

To arrange a return or refund, please contact our Customer Service team via email on info@reflexnutrition.com or call 01273 303817 with your order number and delivery address, and we will guide you through the next steps.

Yes, return shipping is your responsibility to arrange and pay for.

If a delivery fails or you don't collect your parcel and it comes back to us, additional charges may apply.

Refunds go back to your original payment method once we've received and processed your return. Timings vary by payment provider; your bank or card issuer will confirm the exact date.

If there is an issue with your order, please contact our Customer Service team via email info@reflexnutrition.com or call 01273 303817 with your order number and delivery address as soon as possible so we can investigate and resolve the issue.

Items must be unused and in their original, resellable condition, exactly as you received them. Pack them securely in appropriate packaging to protect them in transit.

We can't accept returns that arrive damaged due to poor packaging.

We are unable to accept returns for certain items where it would not be suitable for resale, such as products that have been opened, used, or are not in a resellable condition.

If you no longer have your receipt or order confirmation, please contact our Customer Service team via email info@reflexnutrition.com or call 01273 303817 with as much information as possible (such as your name, email address, or delivery postcode), and we will do our best to locate your order.

Replacements or exchanges will be processed once your returned item has been received and inspected. Delivery times for replacements will follow standard shipping timeframes.

Yes, items purchased using a discount code or as part of a promotion can still be returned, provided they meet the returns criteria. This means items must be unused and in their original, resellable condition, exactly as you received them. Pack them securely in appropriate packaging to protect them in transit.