Does a weight gainer build muscle?

It makes you gain weight if it puts you in a calorie surplus, and part of that weight will be muscle if you train strength and eat enough protein. The gainer supplies nothing food does not: it is a convenient way to add calories when you cannot get them in otherwise.

Is a gainer better than a homemade shake?

Homemade is almost always cheaper. Oats, milk or plant milk, a banana and peanut butter give a similar profile for considerably less money, and they add fibre and micronutrients. The tub wins on convenience and not having to think about it.

Why do weight gainers have no score on this site?

Because there is no effective dose to cite. A gainer is carbohydrate with protein, and its effect is the calories it supplies, not an active at a dose. Scoring it with this site’s method would require inventing a reference, so they are listed by price per kilo, which is exactly what matters in a product bought for its calories.

Does a gainer make you gain fat?

It adds as much fat as the day’s total surplus does. Because you drink it and it is not very filling, it is easy to overshoot without noticing, and a big surplus always brings more fat. If the goal is lean weight gain, a moderate surplus and a weekly weigh-in work better.

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Weight gainers · Moderate evidence

What a weight gainer is for and when it is worth it

The short answer. A weight gainer has no mechanism of its own: it is food in powder form. Its effect is the calorie surplus, and the kitchen achieves that surplus just the same. What you are buying is convenience, not an active ingredient. That is why this category is compared by price per kilo and not scored by dose: there is no effective dose of "weight gainer", there is a total of calories a day.

There are studies in favour, but few, with small samples or measuring markers instead of outcomes. No figure on this page is attributed to a specific product: the effect belongs to the ingredient and every number carries its source next to it.

01 What it does and how much

Each row is a measured effect, with the figure the study gives and the source number. Where the evidence gives no figure, the column says so instead of making up a percentage.

Effects of mass gainer with their source
Effect	How much	Detail
Gaining weight	requires a surplus	All a gainer does is add calories to the day. Without a surplus you do not gain weight with or without a gainer, and with a surplus you gain with or without one. [1]
Daily protein	1.4 to 2.0 g/kg	A gainer supplies protein, but diluted in a lot of carbohydrate. If protein is what is missing, a tub of protein is better value; if calories are missing, the gainer does the job. [2]
Typical gainer split	3:1 or 5:1 carbohydrate:protein	It is mostly sugar and maltodextrin. Worth knowing before paying protein prices for a tub that is mostly carbohydrate. [2]
Muscle gain versus fat	decided by the surplus	A big surplus adds more fat, wherever it comes from. The gainer makes overshooting easier precisely because you drink it without feeling full. [2]

02 How to take it

Dose. Whatever is missing to close your daily surplus. There is no reference dose.
When. When you cannot fit in more food: between meals, after training or as a quick breakfast.
How long before you notice it. Weight goes up within weeks if the surplus is real.

Details that change the result

Do the maths before buying: oats, milk, banana and peanut butter in the blender usually give the same calories for much less money.
Check the split on the label. A "gainer" that is 80 % maltodextrin competes on price with a bag of maltodextrin, not with a protein.
If you have plenty of appetite but lack consistency, a tub will not fix that.
Drinking calories is not very filling: that is an advantage when you cannot eat more and a trap when you already eat enough.

03 When it makes sense and when it does not

Worth it if

You struggle to gain weight from food and your meals are already large.
Long training sessions or high daily expenditure, with little time to cook.
Phases of high training volume when appetite falls short.

Not worth it if

If you already reach your calories. Then you are just buying expensive sugar.
When cutting, for obvious reasons.
As a regular replacement for real food: a gainer has neither the fibre nor the micronutrients of a meal.

04 Sources

Every figure above comes from here. They are position stands from scientific societies, meta-analyses and peer-reviewed reviews: if a claim cannot hang from one of these lines, it is not on the page. References are cited in their original form.

Kerksick CM et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr. 2018;15:38. El balance energetico es lo que determina el cambio de peso; los suplementos calorico-proteicos son una via comoda de alcanzarlo. doi:10.1186/s12970-018-0242-y
Jager R et al. ISSN position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. Ingesta diaria de proteina de 1,4-2,0 g por kilo para quien entrena. doi:10.1186/s12970-017-0177-8

This is not medical advice. It is what some studies say about an ingredient, not a protocol for you. With an illness, medication or pregnancy involved, the decision belongs to a healthcare professional who knows you.

Questions about mass gainer

Answered with the data on this page

Does a weight gainer build muscle?: It makes you gain weight if it puts you in a calorie surplus, and part of that weight will be muscle if you train strength and eat enough protein. The gainer supplies nothing food does not: it is a convenient way to add calories when you cannot get them in otherwise.
Is a gainer better than a homemade shake?: Homemade is almost always cheaper. Oats, milk or plant milk, a banana and peanut butter give a similar profile for considerably less money, and they add fibre and micronutrients. The tub wins on convenience and not having to think about it.
Why do weight gainers have no score on this site?: Because there is no effective dose to cite. A gainer is carbohydrate with protein, and its effect is the calories it supplies, not an active at a dose. Scoring it with this site’s method would require inventing a reference, so they are listed by price per kilo, which is exactly what matters in a product bought for its calories.
Does a gainer make you gain fat?: It adds as much fat as the day’s total surplus does. Because you drink it and it is not very filling, it is easy to overshoot without noticing, and a big surplus always brings more fat. If the goal is lean weight gain, a moderate surplus and a weekly weigh-in work better.

And now, which to buy

Prices, kept apart from the evidence

This page explains what mass gainer does and deliberately names no brand. The comparison is the other half: 96 products from 12 stores from €7.50 per kg, sorted by price and by how verifiable their certification is.

See the weight gainers comparison

Other guides

What each supplement does, with its sources