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Limited evidencePhysical performance

Mass Gainers

A mass gainer is maltodextrin, sugar and whey sold at a premium as a muscle-building product. It works only as calories, and the research on aggressive calorie surpluses shows the extra weight is mostly fat.

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What the science says

  • Mass gainers build muscle Limited evidence

    Nothing in a typical gainer is anabolic beyond its protein and energy content. Meta-analysis of 49 protein supplementation trials found supplemental protein adds about 0.3 kg of fat-free mass over resistance training alone, with benefits plateauing near a total intake of about 1.6 g/kg/day. Once protein and total calories are accounted for, the remaining 150-250 g of maltodextrin per serving is simply energy.

  • A bigger surplus produces faster gains Limited evidence

    Tested directly in elite athletes: a guided high-calorie group ate 3,585 kcal/day versus 2,964 kcal/day ad libitum over 8-12 weeks of strength training. Body weight rose 3.9% vs 1.5%, but fat mass rose 15% vs 3% and the gain in lean body mass did not differ between groups. The extra calories bought fat, not muscle.

  • They are better than food you make yourself Limited evidence

    A typical serving is roughly 1,000-1,250 kcal from about 150-250 g of maltodextrin and sugar plus 40-60 g of whey or casein. Oats, milk, whey, peanut butter and a banana replicate the same macros for a fraction of the price and add fibre and micronutrients. The only genuine advantage is convenience and the fact that liquid calories are easier to consume when appetite is the limiting factor.

  • Added creatine, glutamine or 'anabolic matrices' add value Limited evidence

    Creatine included in a gainer does work, but at 1-3 g per serving it is often below the 3-5 g/day maintenance dose and cheaper to buy separately. Glutamine, tribulus and similar add-ons in these blends have no supporting evidence for muscle gain in healthy people eating enough protein.

Dosage & safety

Studied doseLabel directions typically call for 1-2 servings of 1,000-1,250 kcal per day. The evidence-based approach is much more modest: a surplus of roughly 300-500 kcal/day, targeting about 0.25-0.5% body weight gain per week, with total protein at 1.6-2.2 g/kg/day. Use a gainer, or a fraction of a serving, only to close a real gap you cannot fill with food.
SafetySingle 1,000+ kcal doses with 150 g or more of rapidly digested carbohydrate commonly cause bloating and GI distress and produce large blood glucose excursions; unsuitable for people with insulin resistance or type 2 diabetes. Rapid weight gain at large surpluses is disproportionately fat and worsens blood lipids and insulin sensitivity. Some products contain undisclosed or under-dosed added actives, and protein spiking has been documented in the category, so third-party testing matters, particularly for tested athletes. Lactose content is high in concentrate-based products.

How to take it

TimingTiming does not matter; total daily calories do.
With food?Between meals, or split into halves — a full 1,000+ kcal serving at once is what causes the bloating.
Worth knowingHalf a serving, or oats blended with milk and peanut butter, closes the same calorie gap for less money and less GI distress.

Interactions

With medications

  • insulin and other glucose-lowering drugs

    A single serving can carry 150 g or more of rapidly digested carbohydrate and produce a large glucose excursion. do not use it in diabetes without adjusting medication with your clinician

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Do mass gainers build muscle?

Only as calories and protein; the evidence for mass gainers as muscle builders is limited. Once protein and total calories are accounted for, the 150-250 g of maltodextrin and sugar in a serving is simply energy.

Does a bigger calorie surplus build muscle faster?

No. In athletes eating 3,585 versus 2,964 kcal/day during strength training, the high-calorie group gained more weight, but fat mass rose 15% versus 3% and lean mass gains did not differ.

Are mass gainers better than homemade shakes?

No. Oats, milk, whey, peanut butter and a banana replicate a mass gainer's macros for a fraction of the price, with added fibre and micronutrients; the gainer's only real advantage is convenience.

How much mass gainer should I take?

Use a mass gainer, or a fraction of a serving, only to close a real calorie gap: the evidence supports a surplus of roughly 300-500 kcal/day, not 1-2 servings of 1,000-1,250 kcal. A full serving at once commonly causes bloating and large blood glucose swings.

Scientific references

Where to buy

Dymatize, Super Mass Gainer™, Rich Chocolate, 6 lb (2.7 kg)

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