Optimum Nutrition - Serious Mass

Optimum Nutrition Serious Mass is ON's highest-calorie weight gain formula — up to 1,260 calories, 50g of protein, and up to 253g of carbohydrates per two-scoop serving in water, with over 1,640 calories when mixed with low-fat milk. Built for athletes who struggle to consume enough calories through food alone — the hard gainers, the high-metabolism athletes, the serious mass-seekers who need caloric density that whole food alone can't reliably deliver. Every serving includes 5g of Creatine Monohydrate, 8g of naturally occurring glutamine, 11g of BCAAs, 24g of EAAs, Choline, Inositol, PABA, and 25 vitamins and minerals. The entire 50g of protein comes from Whey Protein Concentrate — fast-digesting, complete protein from milk. No added sugar. Available in Chocolate, Vanilla, Strawberry, Chocolate Peanut Butter, and Banana. 12 lbs per container — approximately 16 full two-scoop servings. New users: start with 1 scoop (half serving) for the first week. Use post-workout and/or between meals. Mix with an electric blender for best results. Contains Milk and Soy (Lecithin).*

Nutrition Facts — Optimum Nutrition Serious Mass (Per 2 Scoops / 334g / ~16 Servings)

Macronutrients (in water)

• Calories: up to 1,260 (up to 1,640+ with low-fat milk)
• Protein: 50g (from Whey Protein Concentrate)
• Total Carbohydrates: up to 253g (No Added Sugar)

Performance Additions

• Creatine Monohydrate — 5g
• L-Glutamine and Glutamine Peptides — 8g naturally occurring glutamine per serving
• BCAAs — 11g per serving
• EAAs — 24g per serving
• Choline, Inositol, PABA

Vitamins and Minerals

• 25 Vitamins and Minerals including Vitamins A, C, E, Zinc (immune support), and B-vitamins (cellular energy conversion)

• Other Ingredients: Maltodextrin, Whey Protein Concentrate, Natural and Artificial Flavor, Sunflower and/or Soy Lecithin, Malic Acid, Acesulfame Potassium, Sucralose
• No Added Sugar
• Allergens: Contains Milk and Soy (Lecithin)
• 12 lbs per container — approximately 16 full two-scoop servings
• Flavors: Chocolate, Vanilla, Strawberry, Chocolate Peanut Butter, Banana
• Mix 2 scoops in 24oz water using an electric blender
• New users: start with 1 scoop (half serving) for the first week
• Use post-workout and/or between meals

Who Serious Mass Is For — The Honest Answer

Serious Mass is not a product for everyone. It's specifically designed for one type of athlete: the person who cannot get enough calories through food alone to support their muscle-building goals. This includes genuinely hard gainers whose metabolisms burn through calories faster than they can consistently consume them through whole food. It includes younger athletes in growth phases with caloric requirements that exceed what regular meals can reliably provide. It includes competitive athletes who need a rapid, convenient calorie delivery method between training sessions and meals. And it includes anyone on a structured mass-building program who has identified their calorie surplus target and found that whole food meals alone aren't hitting it.†

If you're an average-metabolism person who eats a typical three-meal diet and wants to add a protein supplement — Serious Mass is not the right product. Gold Standard 100% Whey or another protein powder is. Serious Mass at 1,260 calories per serving is an entire meal's worth of calories in liquid form. Used correctly — as additional calories on top of a normal diet, not as a replacement for normal eating — it's one of the most effective tools available for building the caloric surplus that muscle growth requires. Used incorrectly — as a meal replacement by someone who didn't need the extra calories — it produces unwanted fat gain without the lean mass goal.†

The Caloric Math — Why 1,260 Calories Matters

Muscle growth requires a caloric surplus — consuming more calories than your body burns in a day. For most individuals, muscle accretion is maximized at a surplus of 250-500 calories per day above total daily energy expenditure (TDEE). For hardgainers and athletes with high metabolisms, TDEE can exceed 3,500-4,000+ calories daily — creating a scenario where eating enough whole food to hit even a modest surplus becomes a logistical challenge that derails consistency. A 300-pound defensive lineman, a 19-year-old cross-country runner trying to add muscle mass, or a competitive bodybuilder in an off-season mass phase all face the same fundamental challenge: getting enough calories.†

One two-scoop serving of Serious Mass in water provides 1,260 calories — approximately 35-50% of most mass-building athletes' daily caloric target in a single drink that takes under two minutes to prepare and under five minutes to consume. Mixed with milk, that number climbs to over 1,640 calories. Add a banana, two tablespoons of peanut butter, and a cup of oats in a blender and a single Serious Mass shake can deliver over 2,000 calories — in under 500ml of liquid. This caloric density is the point of the product.†

The Protein — 50g of Whey Protein Concentrate

The entire 50g of protein in Serious Mass comes from Whey Protein Concentrate — fast-digesting, complete milk-derived protein with the full amino acid profile including 11g of BCAAs and 24g of essential amino acids per serving. Whey protein concentrate (as opposed to Whey Protein Isolate) retains more of the natural bioactive fractions present in milk — including immunoglobulins, lactoferrin, and growth factors — alongside its protein content. At 50g per serving, Serious Mass provides more than enough protein to maximally stimulate muscle protein synthesis from a single shake, with significant room for the leucine threshold that activates mTOR signaling to be exceeded multiple times over.†

The naturally occurring glutamine content (8g per serving) reflects the high glutamine concentration in whey protein — important for recovery, immune function, and the anti-catabolic muscle preservation that keeps the calories Serious Mass provides going to muscle rather than fat. The 5g of added Creatine Monohydrate further supports performance by increasing the phosphocreatine pool that powers explosive training intensity — directly improving the quality of the training sessions that give the surplus calories somewhere anabolic to go.†

The Carbohydrate Profile — Maltodextrin and Fuel

Up to 253g of carbohydrates per serving — the primary macronutrient driver of Serious Mass's caloric density — comes primarily from Maltodextrin, a fast-digesting glucose polymer derived from starch. Maltodextrin is a high-glycemic carbohydrate source that rapidly replenishes muscle glycogen post-workout, triggers the insulin response that facilitates glucose and amino acid uptake into muscle cells, and provides the raw caloric fuel that supports both the training sessions that create the stimulus for muscle growth and the recovery periods when muscle is being rebuilt. In the post-workout window specifically, the combination of Maltodextrin's rapid glycogen replenishment and whey protein's fast amino acid delivery creates the nutrient timing synergy that mass-building protocols are built around.†

Beyond the Basics — Creatine, Glutamine, Choline, Inositol, PABA

Serious Mass includes several compounds beyond the core macronutrient profile that separate it from a simple carb-and-protein powder. The 5g of Creatine Monohydrate per serving is a full daily maintenance dose — meaning on days you take Serious Mass, your creatine supplementation is covered without needing a separate product. L-Glutamine and Glutamine Peptides provide recovery support and immune function maintenance during high-calorie, high-volume training phases. Choline is an essential nutrient involved in acetylcholine synthesis and fat metabolism — important for athletes consuming high-calorie diets where choline demand increases. Inositol participates in cell membrane composition and insulin signaling. PABA (para-aminobenzoic acid) is a B-vitamin family compound with roles in protein metabolism and red blood cell formation. The 25-vitamin-and-mineral panel rounds out the nutritional completeness — covering the micronutrient requirements that intense training and high-calorie consumption elevate.†

How to Use Serious Mass Effectively

Serious Mass works when used as an addition to normal diet — not as a replacement for it. The most effective mass-building protocol using Serious Mass treats the shake as a structured caloric top-up on top of regular meals rather than as a substitute for eating. Post-workout is the primary timing: the combination of fast-digesting whey protein and high-glycemic maltodextrin carbohydrates in the 30-60 minutes following training optimizes the anabolic window for muscle glycogen replenishment and muscle protein synthesis. Between meals is the secondary timing: a half-serving or full serving between two whole-food meals adds structured calories without requiring additional meal preparation.†

New users should start with one scoop (half serving, approximately 630 calories) for the first week to allow the digestive system to adapt to the high-volume caloric intake before advancing to two scoops. Using an electric blender — not a shaker cup — is strongly recommended at two scoops: the volume and viscosity of Serious Mass at full serving requires blending for complete dissolution and smooth consistency. Adding ice, frozen fruit, peanut butter, oats, or other calorie-dense ingredients to the blender at full serving can push a single shake well above 2,000 calories for athletes with the highest caloric requirements.†

Frequently Asked Questions

1. How many servings are in a 12 lb container of Serious Mass?
   The 12 lb (5.44kg) container provides approximately 16 full two-scoop servings at the standard 334g serving size. Serving count can vary slightly depending on how leveled the scoops are. For new users taking half servings (1 scoop) during the initial week, the container provides approximately 32 half servings. At full two-scoop daily use, a 12 lb container lasts approximately 16 days.†
2. Should I mix Serious Mass with water or milk?
   Both are appropriate depending on your caloric goals. In water: up to 1,260 calories, 50g protein, up to 253g carbohydrates. In low-fat milk: up to 1,640+ calories with additional protein and calcium from the milk. Water is the standard recommendation for calorie tracking precision. Milk is the recommendation for athletes who need the maximum calories and prefer the thicker, creamier consistency. New users often find the water version easier to consume initially due to the lower volume density.†
3. Why does Serious Mass include Creatine?
   The 5g of Creatine Monohydrate per serving covers the full daily maintenance dose for phosphocreatine saturation — eliminating the need for a separate creatine supplement on days you use Serious Mass. Creatine directly supports the explosive training intensity that gives the caloric surplus somewhere anabolic to go — heavier loads, more reps, more total training volume. Including creatine in a mass-gaining formula reflects ON's understanding that caloric surplus alone doesn't build muscle — you have to train hard enough to create the stimulus first.†
4. Is Serious Mass appropriate for diabetics or people with blood sugar concerns?
   No — not without physician clearance. Serious Mass's primary carbohydrate source is Maltodextrin — a high-glycemic carbohydrate that produces a significant blood glucose and insulin spike. Diabetics, hypoglycemics, and individuals with blood sugar regulation disorders must consult a physician before use. This is explicitly noted on the Serious Mass label.†

How to Take Optimum Nutrition Serious Mass

Add 2 heaping scoops to a blender with 24oz of cold water or low-fat milk. Blend for 45-60 seconds. Add ice cubes and optional calorie-contributing ingredients (fruit, peanut butter, oats) and blend for an additional 30-45 seconds if desired. New users: start with 1 scoop in 12oz water or milk daily for the first week, then gradually increase to the full 2-scoop serving. Use post-workout and/or between meals to add calories, carbohydrates, and protein to a healthy, balanced diet. Do not use as a meal replacement — use as an addition to existing dietary intake. Not for pregnant or nursing women. Do not use if you are a diabetic or hypoglycemic without physician clearance. Contains Milk and Soy (Lecithin). Keep out of reach of children.*

Why Buy at Get Yok'd

• Real-time inventory across all five Southern California stores
• Available in Burbank, Glendale, Glendale Galleria, Pasadena, and North Hollywood
• Authorized Optimum Nutrition retailer — the world's number one sports nutrition brand
• All five Serious Mass flavors available — ask staff for current in-store flavor selection
• Staff who can help you build the right mass-gaining protocol around Serious Mass
• One of the best loyalty programs in the supplement industry — earn rewards on every purchase

Who Should Exercise Caution with Serious Mass

• Not for pregnant or nursing women
• Diabetics and hypoglycemics must consult a physician before use — high glycemic maltodextrin carbohydrates produce significant blood glucose and insulin response
• Individuals with milk protein allergies should not use — primary protein source is Whey Protein Concentrate from milk
• Individuals with soy allergies should note the product contains Soy (Lecithin)
• Individuals who are not in caloric deficit for mass-building purposes should not use Serious Mass as a regular supplement — 1,260 calories per serving will produce fat gain in individuals without a genuine caloric need for the surplus
• Individuals with kidney disease should consult a physician — high protein and creatine intake increases renal processing demand
• Consult a physician before use if taking any prescription medications
• Keep out of reach of children.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.