Optimum Nutrition Serious Mass is a high calorie mass builder that helps you pack muscle and bulk up quickly by delivering dense calories, plenty protein, and clever carbs. Protein from whey concentrate, calcium caseinate and egg albumen delivers steady amino acids to fuel muscle growth, mirroring Optimum Nutrition's pledge to quality. Creatine monohydrate powers strength during hard sessions, and quick acting carbohydrates top up energy and speed recovery.

Benefits & Features:

• Dense calories support rapid mass gains.
• Protein blend powers muscle recovery after tough sessions with steady amino acids.
• Creatine monohydrate supports ATP regeneration for stronger workouts, while a high carbohydrate blend replenishes glycogen stores to keep energy levels high through demanding training sessions.
• Glutamine and B vitamins support metabolic function and recovery after workouts.
• Quality is assured by GMP compliant facilities and NSF testing.

Optimum Nutrition Serious Mass blends whey concentrate, calcium caseinate and egg albumen with maltodextrin to deliver a dense, calorie rich shake. Trusted by athletes. The range is manufactured in NSF certified facilities, with third-party testing to verify purity. Creatine monohydrate supports strength, and glutamine plus B vitamins back recovery and metabolic function. Crafted to the highest standards, with a long standing history in sport nutrition, this mass gainer is built for serious training and steady progress. It also serves as a reliable protein powder for muscle gain, helping you reach your goals without compromise.

Maltodextrin, Protein Blend (Whey Protein Concentrate, Calcium Caseinate, Egg Albumen, Sweet Dairy Way), Creatine Monohydrate, L-Glutamine, Glutamine Peptides, Choline (as Choline Bitartrate), Inositol, Paba (Para-Aminobenzoic Acid), Artificial Flavor, Vitamin & Mineral Blend (Di-Potassium Phosphate, Magnesium Aspartate, Di-Calcium Phosphate, Calcium Citrate, Ascorbic Acid, Niacinamide, Zinc Citrate, Beta Carotene, d-Calcium Pantothenate, d-alpha Tocopherol Succinate, Selenomethionine, Copper Gluconate, Ferrous Fumarate, Manganese Amino Acid Chelate, Thiamin Mononitrate, Pyridoxine Hydrochloride, Riboflavin, Chromium Picolinate, Folic Acid, Biotin, Molybdenum Amino Acid Chelate, Cholecalciferol, Potassium Iodide, Cyanocobalamin), Medium Chain Tri-glycerides, Acesulfame Potassium

• GTIN: 5060469988368
• Manufacturer: Optimum Nutrition
• Size: Strawberry / 2.73kg
• Categories: Bodybuilding SupplementsCHECKOUT UPSELLNew ArrivalsNew In Supplements & VitaminsOptimum NutritionSports Supplements
• Best buy: 6 - 24 months+

United Kingdom Shipping:

Orders placed by 2pm (Monday to Friday) are dispatched the same day. Orders placed after 2pm will be dispatched the next working day.

Free shipping on orders over £50 to the UK.

Returns: Our products are meant to make you feel healthy and at your best. If you need to return your item, you can do so free of charge within 30 days in the same original and unopened packaging. Subject to T&C's.

For best results, consume this 1263-calorie serving mindfully. Each portion delivers 50g of muscle-supporting protein and 251g of energy-rich carbohydrates. Monitor your saturated fat intake, with 2.4g present per serving from the total 5.5g fat content. The 26g of sugars and 3.2g of fiber support balanced energy release. Contains 1.56g salt - adjust other daily sodium intake accordingly. (5284 kJ total energy value)

Please consult the product packaging for accurate instructions on how to use the product.

The Active Ingredient Is: Protein (Whey Protein)

Protein plays a role in providing essential amino acids that support normal muscle maintenance and growth as part of a balanced diet.

This form combines whey protein with dairy and egg-derived proteins to deliver a complete amino acid profile in a highly bioavailable form.

What Does Protein Do?

Protein assists with muscle protein synthesis and recovery following exercise, supporting daily fitness goals. This function aligns with EFSA and NHS guidance on protein’s role in everyday muscle health.

Evidence from sports nutrition research supports the importance of adequate protein intake to support muscle growth when paired with physical activity.

Optimum Nutrition sets a science‑driven standard in sports nutrition, and this brand’s commitment to manufacturing excellence informs why we chose them as our supplier for Serious Mass. Their facilities operate under GMP and are NSF International certified, underpinning rigorous quality and safety alongside third‑party testing for label accuracy and ingredient purity. This focus on dependable manufacturing aligns with our own quality assurance practices, which are verified by our quality certification process.

Our vetting criteria centre on credibility, traceability, and manufacturing integrity, and Optimum Nutrition consistently meets these benchmarks with a long‑standing reputation in the industry as a global leader in weight‑gainer formulation. This brand’s heritage in delivering high‑calorie, protein‑rich supplements positions it as a natural fit for Serious Mass, supporting a product that is designed for individuals with high energy needs to gain mass and recover after training.

We selected Optimum Nutrition because this brand demonstrates robust quality standards, clear manufacturing controls, and a proven track record in the British market. This partnership is reinforced by our expert team of doctors, nurses, and nutritionists and aligns with our commitment to transparency and trusted supplementation for on‑course delivery to customers.