Welcome to AOB Nutrition

Unfortunately our website doesn't look so great in your current browser

Do yourself a favour and check us out using Google Chrome or Mozilla Firefox

Or call us now on 01 443 262
Are you from Dublin 1-4, 6-12, 15, 20 or 22?
Yes No

Optimum Nutrition Serious Mass 5.45kg

Optimum Nutrition Serious Mass 5.45kg
Chocolate Peanut Butter
RRP: €73.99
16 servings / 8 daily servings
€2.81 per serving / €5.62 per day
3 In Stock

Optimum Nutrition Serious Mass 5.45kg

When You're Serious About Building Mass - Serious Mass

Delicious flavour & texture
1,250kcal per serving
50g of Blended Protein
250g Carbohydrates with No Added Sugar
Added Creatine, Glutamine and Glutamic Acid
25 Vitamins & Essential Minerals

Optimum Nutrition’s award-winning Serious Mass is the ULTIMATE weight gain formula. If you find it difficult to gain weight and muscle, Serious Mass will help you develop the physique you've always wanted by adding high quality protein and calories.

What is Serious Mass?

Each delicious shake delivers an incredible 1,250 calories, but with no added sugar. This includes 50g of blended protein to support the growth and maintenance of muscle, along 250g of carbohydrates and added creatine, glutamine, glutamic acid and 25 key vitamins and minerals.

When Should I Enjoy My Shake?

Simply mix 2 scoops with milk or water in a shaker and enjoy between meals, post-workout and/or before bed.

Suitable for vegetarians.

Chocolate Peanut Butter
Cookies & Cream

Please Note: Products that are sold in bags rather than tubs are more prone to damage. If the products arrive to us damaged but with only negligible loss of product, we will mend the damaged packaging and then treat it as normal. If there is significant loss of product, we will clearly state this. We take extra care when packaging these products for delivery to our customers, but we cannot guarantee their arrival without any damage. If the loss of product is less than one-percent (a third of a scoop) we do not accept any liability. If the loss of product is more significant, please contact us. Thank you for your understanding.

While we do our best to keep this information up-to-date, manufacturers sometimes update their product formulas without warning. Please read the label before opening.
Please note that nutritional values may vary between flavours. Manufacturers may also update the formula without warning. Please contact us if you have any questions regarding the nutritional information, and please read the label before opening.

Here at AOB Nutrition we like to reward our customers. When you buy Optimum Nutrition Serious Mass 5.45kg, you will earn 42 Reward Points worth €0.42. You can redeem your AOB Real Rewards on any future order, simply apply them during checkout. Read more

DUBLIN - Available within our Flexi-Fast delivery area: Dublin 1 - 24 (exc. D 13), Swords, and Dun Laoghaire-Rathdown

Flexi-Fast Same Day Delivery

FLEXIBLE Choose either daytime or evening delivery
FAST Order before 9am for daytime delivery, or before 5pm for evening delivery

FREE when you spend just €50
€2.99 when you spend €25
€4.99 on orders less than €25

Free Standard Delivery

Free delivery available to all orders (over €3.99) within our Flexi-Fast area.
When checking-out, choose three suitable delivery times and we will deliver during one of these as soon as possible

Read more
Ireland - Nationwide Next-Day Delivery

NEXT-DAY DELIVERY - DPD Couriers / An Post

94% of orders placed before 5pm are delivered next working day

FREE when you spend just €60
€1.99 when you spend €40
€3.99 when you spend €20
€5.99 on orders less than €20

Read more
U.K. - Two-Day Delivery

Available throughout the U.K.

Order before 4.00pm Monday - Friday for Same Day Dispatch.
Our website checkout is currently unable to handle U.K. orders, please contact us to place your order

Read more

Please note: couriers do not work weekends or Bank Holidays.


Unhappy with your purchase? Changed your mind? No problem!

Simply return the product to us unopened and in it's original condition and packaging within 14 days.
Once we have received the product(s), we will issue a full refund excluding shipping charges.
[Excludes short-dated products]

Flexi-Fast Area

We can arrange free collection of returns within 3 working days. Please contact us to arrange.


You have two options: (a) Arrange the return yourself or (b) We can arrange collection of the product (small charge will apply). Once we have received the product and confirmed that it is in it's original condition, we will then issue a full refund excluding the shipping / collection charges. Please contact us before returning.

Credit / Debit Card

To maximize security while shopping online with us, all credit and debit card transactions are handled securely by NetPay. Through their encrypted network, NetPay can securely process transactions while keeping your sensitive details hidden.


When you pay using PayPal, they hide your financial details to protect you from fraud. PayPal delivers one of the most secure payment platforms in the world. After more than a decade as a leader in online payments, they've learned a thing or two about keeping your information safer.

Cash on Delivery

Available within our Flexi-Fast Delivery area.

We accept Cash on Delivery - just like when you get pizza delivered!
Cash on Delivery orders must be signed-for on delivery. You will then receive a receipt of payment via email.
Read more here