Mass gainer
Convenient calories with protein when you can't eat enough food
What it is
A high-calorie blend of protein and carbohydrate. The sources don't use the word “gainer”; the closest categories are high-calorie carbohydrate/protein supplements (ISSN) and mixed macronutrient supplements (AIS).
Benefits
It is a compact way to add energy and protein. Protein combined with resistance training helps build lean mass (IOC). Adding carbohydrate to protein matters little once protein needs are met (ISSN), but it helps you reach the energy intake you need, and that too may affect results.
Dose
The sources give no recommended dose. AIS says the amount depends on the purpose, and that the product should add to regular food rather than replace it.
When to take it
Before exercise, after exercise, or as a snack between meals (AIS). According to ISSN, once protein needs are met, the exact timing of carbohydrate matters little.
Who it's for
People gaining mass or training with heavy loads who can't eat the amount of food they need, especially when appetite is low (AIS, IOC).
Who can skip it
With general fitness, 30–40 minutes 3 times a week, a normal diet covers your needs (ISSN). AIS: such products aren't needed at every session or in the everyday diet; whole foods are more cost-effective and give a wider range of nutrients.
Safety
Most people tolerate it well; a few get significant gut issues (AIS). Too many energy-dense, low-satiety shakes can upset energy balance and diet quality. Such blends have less protein than protein powder and fewer micronutrients than food. Possible allergens: milk, tree nuts, gluten. We found no data for pregnancy or diabetes: see a doctor first.
Work out your numbers
This is a summary of public sources, not medical advice. If you have a health condition, are pregnant or take medication, talk to a doctor before taking a supplement.
Sources
- ISSN exercise & sports nutrition review update: research & recommendations . ISSN, 2018.
- ISSN position stand: nutrient timing . ISSN, 2017.
- IOC consensus statement: dietary supplements and the high-performance athlete . IOC, 2018.
- AIS Sports Supplement Framework — Mixed Macronutrient Supplement, Practitioner Fact Sheet . AIS, 2025.
- AIS Sports Supplement Framework — Isolated Protein Supplements, Practitioner Fact Sheet . AIS, 2025.
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