Protein

Optimum Nutrition Serious Mass 12lb

$119.99

Flavour

Add to cart

5% off any 2 · 10% off any 3 · 15% off any 5 – applied automatically in your cart.

Serious Mass is Optimum Nutrition’s classic gainer for athletes who need a big calorie surplus to keep the scale moving.

The 12 lb bag delivers a deep bench of servings for a sustained gaining phase.

Nutrition information is on the product packaging. Values vary slightly by flavour — the tub label is the authority.

Shipping. Orders placed before 2 pm ET on weekdays ship the same day. Standard shipping is free over $99; below that it's calculated at checkout. Most of Ontario and Quebec sees delivery in 1–3 business days; Western Canada and the Atlantic provinces in 3–6.
Returns. Unopened products can be returned within 14 days of delivery for a full refund. Opened tubs can't be restocked - if something's wrong with your order, contact us and we'll make it right.
Freshness. Everything ships sealed, from authorized Canadian distribution. If your order arrives short-dated, contact us and we'll replace it or refund it.

More Products

Performance

Weight Management

Weight Management