We Tested 23 Mass Gainers in the UK — Scores, Reviews & Prices
High-calorie mass gainer protein powders for muscle and weight gain.
We analysed 23 mass gainers using currently available review and product data from public sources. We evaluate each product across six categories — effectiveness, ingredient quality, value for money, side effects, certifications, and overall score — so you can make an informed decision without spending hours reading individual reviews.
🏆 View Best Mass Gainers 2026 Rankings →What are the best mass gainers in 2026?
According to the AIScored 0–100 scoring system, the highest-rated mass gainers in the UK are: Critical Mass Professional Lean Mass Gainer Banana 2.4kg (16 Servings) (80.0/100), Informed Mass, Strawberries and Cream, 3kg (77.0/100), Critical Mass Professional Lean Mass Gainer Strawberry 6kg (40 Servings) (74.0/100). Rankings are based on 23 products scored across effectiveness, ingredient quality, value for money, side effects, and certifications.
| Rank | Product | Brand | Score | Price |
|---|---|---|---|---|
| #1 | Critical Mass Professional Lean Mass Gainer Banana 2... | Applied Nutrition | 80.0/100 | £40.00 |
| #2 | Informed Mass, Strawberries and Cream, 3kg | Bulk | 77.0/100 | £45.00 |
| #3 | Critical Mass Professional Lean Mass Gainer Strawber... | Applied Nutrition | 74.0/100 | £52.95 |
| #4 | Optimum Nutrition Serious Mass Protein Powder High C... | Optimum Nutrition | 72.0/100 | £52.95 |
| #5 | Critical Mass Professional Lean Mass Gainer Vanilla ... | Applied Nutrition | 71.0/100 | £62.76 |
| #6 | Serious Mass Vanilla 1.34kg | Optimum Nutrition | 70.0/100 | £21.00 |
| #7 | Serious Mass Vanilla 2.73kg | Optimum Nutrition | 70.0/100 | £39.17 |
| #8 | Serious Mass Strawberry 5.4kg | Optimum Nutrition | 70.0/100 | £52.95 |
| #9 | Critical Mass Professional Lean Mass Gainer Chocolat... | Applied Nutrition | 70.0/100 | £75.00 |
| #10 | Serious Mass Banana 2.73kg | Optimum Nutrition | 70.0/100 | £40.00 |
23 products
Which mass gainers rank highest in 2026?
View full rankings →
Critical Mass Professional Lean Mass Gainer Banana 2.4kg (16 Servings)
Applied Nutrition
Applied Nutrition Critical Mass Professional is a high-calorie lean mass gainer (1,000+ calories per serving) designed f...
Informed Mass, Strawberries and Cream, 3kg
Bulk
Bulk's Informed Mass is a premium lean mass gainer built around a tri-protein blend (whey concentrate, isolate, and case...
Critical Mass Professional Lean Mass Gainer Strawberry 6kg (40 Servings)
Applied Nutrition
Applied Nutrition Critical Mass Professional is a high-calorie lean mass gainer delivering 1,000+ calories and 42g of pr...
Optimum Nutrition Serious Mass Protein Powder High Calorie Mass Gainer
Optimum Nutrition
Optimum Nutrition Serious Mass is one of the market's most established mass gainers, delivering approximately 1,250 calo...
Critical Mass Professional Lean Mass Gainer Vanilla 6kg (40 Servings)
Applied Nutrition
Applied Nutrition Critical Mass Professional is a high-calorie lean mass gainer delivering over 1,000 calories and 42g o...
Serious Mass Vanilla 1.34kg
Optimum Nutrition
Optimum Nutrition Serious Mass is a high-calorie weight gain formula delivering 1260+ kcal per serving with 50g protein,...
Serious Mass Vanilla 2.73kg
Optimum Nutrition
Optimum Nutrition Serious Mass is a high-calorie weight gain formula delivering 1,260 kcal and 50g protein per serving, ...
Serious Mass Strawberry 5.4kg
Optimum Nutrition
Optimum Nutrition Serious Mass is a long-established, high-calorie mass gainer delivering 1,258 kcal and 53 g of blended...
Critical Mass Professional Lean Mass Gainer Chocolate 2.4Kg (40 Servings)
Applied Nutrition
Applied Nutrition Critical Mass Professional is a high-calorie lean mass gainer delivering 1,000+ calories per serving w...
Serious Mass Banana 2.73kg
Optimum Nutrition
Serious Mass is a high-calorie weight gain formula by Optimum Nutrition containing 1,250 calories and 50g protein per se...
Serious Mass Chocolate Peanut Butter 2.73kg
Optimum Nutrition
Serious Mass is a high-calorie weight gain formula by Optimum Nutrition delivering 1,263 kcal and 50g protein per servin...
Serious Mass Cookies & Cream 2.73kg
Optimum Nutrition
Serious Mass Cookies & Cream is a high-calorie weight gain formula by Optimum Nutrition delivering 1,250 calories and 50...
Serious Mass Cookies & Cream 5.4kg
Optimum Nutrition
Serious Mass is a high-calorie weight gain powder designed for muscle building with 1,250 calories, 50g protein, and 3g ...
Universal Nutrition Real Gains Weight Gainer 3.17kg
Universal Nutrition
Universal Nutrition Real Gains is a long-standing mass gainer featuring a dual protein blend of whey concentrate and mic...
Serious Mass Chocolate 2.73kg
Optimum Nutrition
Optimum Nutrition Serious Mass is a long-established, high-calorie mass gainer delivering 1,250 calories and 50g protein...
Serious Mass Powder Banana 5.4kg
Optimum Nutrition
Optimum Nutrition Serious Mass is one of the most established mass gainers on the market, delivering approximately 1,250...
Serious Mass Chocolate Peanut Butter 5.45kg
Optimum Nutrition
Optimum Nutrition Serious Mass is a long-established high-calorie mass gainer delivering 1,263 kcal and 50g protein per ...
Serious Mass Chocolate 5.4kg
Optimum Nutrition
Optimum Nutrition Serious Mass is a long-established, high-calorie mass gainer delivering 1,263 kcal, 50g protein, and 2...
Critical Mass Professional Lean Mass Gainer Banana 6kg (40 Servings)
Applied Nutrition
Applied Nutrition Critical Mass Professional is a high-calorie lean mass gainer delivering over 1,000 calories per 150g ...
Serious Mass Strawberry 2.73kg
Optimum Nutrition
Optimum Nutrition Serious Mass is one of the most established mass gainers on the market, delivering 1,258 kcal and 53g ...
Bulk Complete Mass Gainer
Bulk
Bulk Complete Mass Gainer is a high-calorie powder delivering 500 kcal, 45g protein, and 65g carbohydrates per 135g serv...
Serious Mass Vanilla 5.4kg
Optimum Nutrition
Optimum Nutrition Serious Mass is a long-standing, high-calorie mass gainer delivering 1,250 calories and 50g protein pe...
Serious Mass Chocolate 1.34kg
Optimum Nutrition
Optimum Nutrition Serious Mass is a long-standing, high-calorie mass gainer delivering 1,250 kcal, 50 g protein and over...
What are the most popular uses for mass gainers?
Filter products by common goals and user profiles in this category.
How do the top mass gainers compare head-to-head?
See all side-by-side comparisons between mass gainers products.
How does AIScored compare mass gainers?
We collect currently available review and product data from public sources to build a complete comparison baseline.
We read every review, check ingredient labels, fillers, and certifications, then generate an unbiased summary.
Products are scored 0-100 across evidence-based categories, making it easy to compare at a glance.
What should you look for when buying mass gainers?
Choosing the right mass gainers can be overwhelming with hundreds of options on the UK market. Here are the key factors we analyse when scoring each product:
Bioavailability & Forms
Not all ingredient forms are equally effective. We check which forms are used and whether they're backed by research for optimal absorption and bioavailability.
Clean Label & Fillers
Many products contain unnecessary fillers, artificial colours, added sugars, and bulking agents. We flag products with excessive additives and reward clean formulations.
Third-Party Testing
Independent lab testing verifies that what's on the label is actually in the product. Products with third-party certifications (NSF, USP, Informed Sport) score higher in our rankings.
Value per Serving
The cheapest option isn't always the best value. We calculate the cost per serving and weigh it against ingredient quality, dosage, and overall effectiveness reported by users.
How Our Scoring Works
Each product is scored 0-100 across evidence-based categories. An overall score of 80+ indicates a product we'd recommend to most people. Scores of 60-79 are solid choices with some trade-offs, while anything below 60 has significant drawbacks reported by users. Our scores are recalculated regularly as new reviews and ingredient data come in.
Frequently Asked Questions
Where do you get your reviews?
We aggregate publicly available review and product data from retailer pages, communities, and specialist sources. We do not use manufacturer-provided testimonials as evidence.
How often are scores updated?
We re-analyse reviews and update scores regularly. Product pages show the date of the latest analysis.
Do you receive products for free?
No. AIScored does not accept free products or sponsored placements. Our revenue comes from affiliate links, which do not influence our scores.
What is the best mass gainers in 2026?
Based on our analysis of 23 products, the top rated mass gainers is Critical Mass Professional Lean Mass Gainer Banana 2.4kg (16 Servings) with a score of 80.0/100.
How many mass gainers products have you reviewed?
We have analysed 23 mass gainers products, scoring each on effectiveness, ingredient quality, value for money, side effects, and certifications.
What other categories are related to mass gainers?
Disclaimer: AIScored provides research-backed summaries based on publicly available reviews and product information. This is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Prices are updated regularly but may differ at the time of purchase. Affiliate links may earn us a commission at no extra cost to you.