Compare mass gainers on the calories, protein, carbohydrate and sugar in each serving, and on the cost per serving. They are high-calorie shakes, and some provide over 1,000 calories at the full serving, so check the label and make sure the numbers fit what you actually need.
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What is a mass gainer?
A mass gainer, or weight gainer, is a powder that mixes protein with a large amount of carbohydrate, and sometimes fat, to give a lot of calories in one shake. The main difference from a standard protein powder is the carbohydrate: a gainer is mostly carbs, while a protein powder is mostly protein.
Some gainers in this collection also list oats or added creatine in the product name. Check the label for the carbohydrate source, the sugar content and anything else that's been added, so you know what each serving contains.
How many calories are in a mass gainer?
It varies widely: some gainers provide a few hundred calories per serving, while others are designed to provide well over 1,000 at the full recommended serving. Read the calories for the serving you'll actually use, because the label's serving can be several scoops.
For context, the NHS says an average man needs 2,500kcal a day and an average woman 2,000kcal, and that you're likely to put on weight if you eat and drink more calories than you use. A full-serving gainer shake can be half of a day's calories on its own.
How much sugar is in a mass gainer?
Many mass gainers contain a lot of sugar, often from maltodextrin, dextrose or fructose, so check "of which sugars" on the nutrition label. The NHS says adults should have no more than 30g of free sugars a day, and a single gainer serving can contain more than that, so check the label.
Maltodextrin is a carbohydrate made from starch; it usually counts towards carbohydrate rather than sugars on the label, but it's still a fast-digesting source of calories. The NHS classes food with more than 22.5g of total sugars per 100g as high in sugar, which is a useful benchmark when you compare gainers.
Do mass gainers work?
A mass gainer only adds calories, protein and carbohydrate; it doesn't do anything a meal with the same nutrients wouldn't. If you're eating more calories than you use, you'll gain weight; whether that's muscle or fat depends largely on your training and overall diet.
The British Dietetic Association says muscle gain needs a combination of resistance training and enough protein, around 1.6 to 1.7g per kilogram a day. Where a gainer is at least a source of protein, the authorised claim is that "protein contributes to a growth in muscle mass", and that applies to any food that is at least a source of protein, not just gainers.
Is a mass gainer bad for you?
Not in itself, but the calories and sugar are high, and relying on shakes rather than food has trade-offs. The NHS advice on gaining weight is to gain weight gradually by adding healthy calories, around 300 to 500 extra calories a day, and not to rely on chocolate, cakes and sugary drinks.
That's far less than many gainer servings provide. If you're underweight, have lost weight without trying, or have a medical condition such as diabetes, speak to your GP before using high-calorie products. The NHS says to speak to a GP if you've lost weight suddenly.
Mass gainer or protein powder?
If you mainly want more protein, a standard protein powder gives you more of it for fewer calories. If you struggle to eat enough food overall, a gainer adds calories as well.
"The amount of protein on the front of the packaging doesn't always tell you which product offers the best value," says Andy Arshad, who runs SupplementHQ. Some people make their own version by mixing whey protein with oats or milk, which lets you control the sugar.
| Per serving (typical label ranges) | Mass gainer | Standard protein powder |
|---|---|---|
| Main ingredient | Carbohydrate | Protein |
| Calories | Several hundred to over 1,000 | Much lower; check the label |
| Protein | Varies; check the label | Most of the calories |
| Sugar | Often high | Usually low |
How do you compare mass gainers on value?
Compare the cost per serving at the serving size you'll actually use, then look at the calories and protein in that serving. A tub listing many servings might assume a smaller scoop than the "full" serving on the front.
How to compare value (example figures, not real products): a £40 tub of 5kg with a 250g serving gives 20 servings at £2 each. If one serving has 1,000kcal and 50g of protein, that's 20p per 100kcal and £1 per 25g of protein. A £30 tub of 3kg with a 100g serving gives 30 servings at £1 each; if each has 380kcal and 30g of protein, that's about 26p per 100kcal and about 83p per 25g of protein. The first gives cheaper calories, the second cheaper protein.
"Two products that look almost identical on the shelf can offer different value," says Andy.
How much protein should a gainer have?
There's no set amount, but the ISSN suggests 20 to 40g of protein per serving as a general guide, with total daily protein of 1.4 to 2.0g per kilogram of body weight for most people who exercise. Many gainers fall within that range at the full serving.
Check the protein-to-carbohydrate ratio on the label. If protein is a small share of the calories, you're mostly buying carbohydrate. Compare against our protein powder hub to see the difference.
We sell the products on this page. That's our commercial interest, and it's why we show the evidence alongside them. This page is general information for adults, not personalised medical advice. Food supplements should not replace a varied, balanced diet.
Written by Andy Arshad, SupplementHQ. Last reviewed 11 October 2026.