Mass Gainer for Muscle Gain: When It Makes Sense and What the Research Says

Anyone who has ever been "the skinny one in the group" knows the frustration. You're sure you eat a lot, you train at the gym, and the scale doesn't move. And then, at the supplement store, the seemingly obvious solution awaits: a giant 3 kg bucket with MASS written on it in big letters. The promise sounds simple: drink, grow. A mass gainer is one of the first supplements that "hardgainers," skinny people who struggle to gain weight, buy.

But there's a fact that the marketing emphasizes less: a mass gainer is mostly powdered food. A single serving of a "heavy" mass gainer can contain more than 1,200 calories, about the same as two regular meals, and about 80% of them come from carbohydrates. There is no ingredient in the powder that turns calories into muscle. Muscle is built from three things: a moderate caloric surplus, enough protein, and progressive strength training. In this guide we'll explain what a mass gainer actually does, what the research says about how much surplus is needed, when it is useful, who should avoid it, how to choose between three popular products, and how to make a homemade shake with a similar result at a lower cost. Rating: yellow.

What is a mass gainer?

A mass gainer (Mass Gainer or Weight Gainer) is a shake powder designed to deliver a lot of calories in a relatively small volume. Here's what's important to know:

• Calorie-dense powder: A single serving usually ranges from about 400 to about 1,300 calories, depending on the product and serving size.
• Mostly carbohydrates: In most mass gainers, most of the calories come from carbohydrates, usually maltodextrin, a processed carbohydrate that breaks down quickly into glucose. In "heavy" mass gainers, carbohydrates make up about 80% of the calories.
• Plus some protein: Alongside the carbohydrates there are usually 30-60 grams of protein per serving, mostly from milk proteins.
• Additives: Some products add vitamins, minerals, and sometimes also creatine. It's important to check the label so you don't take a double dose.
• The difference from protein powder: A regular serving of protein powder provides about 110-130 calories, most of them from protein. A mass gainer provides 3 to 10 times the calories, and most of them are not from protein.

The connection to muscle building: why a mass gainer doesn't build mass on its own

To understand what a mass gainer can and cannot do, you need to understand what builds muscle. There are three conditions, and all of them are required together. Progressive strength training (gradually increasing weights, reps, or volume) is the signal that tells the body "we need to build here." Protein is the building material. And a caloric surplus is the energy that funds the construction, which is an energetically expensive process.

A mass gainer touches only two of the three: calories and some of the protein. It doesn't provide the signal. Without strength training, surplus calories are stored mainly as fat, and there is no ingredient in the powder that "directs" them to muscle. In terms of energy balance, 1,000 calories from a mass gainer are equal to 1,000 calories from rice, chicken, bread, and tahini. The difference is not in the biology, but in the convenience.

And that's exactly where a mass gainer can help. For many skinny people, it's physically hard to eat more: appetite shuts down after a big meal, the schedule is busy, and they tend to overestimate how much they actually eat. Drinking 600 calories is easier for many people than eating them. In other words, a mass gainer is a logistical tool for solving an appetite and time problem, not a magic ingredient.

The current evidence

An honesty note before anything else: there are very few controlled trials on mass gainer powders themselves. Most of the knowledge comes from studies on the building blocks: how much caloric surplus is needed, how much protein is beneficial, and what happens when the surplus is too large. Therefore the evidence here is mainly about the principles, plus one older trial that tested a mass gainer directly.

Study 1: Iraki et al. 2019, how much surplus is really needed

A review by Juma Iraki, Eric Helms, and colleagues, published in the journal Sports, summarized the scientific literature on the nutrition of natural bodybuilders during the "bulking" phase. The main recommendations: a caloric surplus of about 10-20% above maintenance, and weight gain of about 0.25-0.5% of body weight per week for beginner and intermediate trainees, with a more conservative surplus for advanced trainees. Alongside this, protein at 1.6-2.2 grams per kilogram of body weight per day, divided into 3-6 meals of about 0.40-0.55 grams per kilogram each, a moderate amount of fat (0.5-1.5 grams per kilogram), and a sufficient amount of carbohydrates (3-5 grams per kilogram and up) to fuel training.

Translated into numbers: someone weighing 65 kg who maintains their weight on about 2,600 calories per day needs a surplus of about 260-520 calories, and a gain of about 160-325 grams per week. That's much less than most people imagine. Another review by Gary Slater, Eric Helms, and colleagues in Frontiers in Nutrition from 2019 adds an important caveat: the optimal surplus for muscle building has never been precisely verified in research, and therefore the recommendations are ranges, not a formula. It also addresses the practical problem of satiety when trying to increase caloric intake.

Study 2: Helms et al. 2023, a large surplus adds mostly fat

A controlled trial by Eric Helms and colleagues, published in Sports Medicine - Open, randomly assigned 21 strength trainees to three groups: maintenance nutrition, a moderate 5% surplus, and a high 15% surplus. All trained 3 times a week for 8 weeks. Due to the COVID-19 pandemic, only 17 completed the study.

The researchers' conclusion: a faster rate of weight gain, and consequently a larger surplus, added mostly fat (as measured by skinfold thickness), and did not clearly increase muscle thickness or strength. There were a few outlier findings: in the comparison between groups, evidence was found for a greater improvement in bench press in the high-surplus group, and the triceps muscle may have benefited slightly. But the overall trend is clear. This is a small and short study, so caution is needed, but it aligns with logic: the body has a limited rate of muscle building, and calories beyond that go to storage. And here is exactly the problem with heavy mass gainers: a full serving of 1,250 calories, if added on top of the regular diet, is about 2.5 to 5 times the entire recommended daily surplus for the person in the example above.

Study 3: Morton et al. 2018, the protein ceiling

A meta-analysis by Robert Morton, Stuart Phillips, and colleagues, published in the British Journal of Sports Medicine, combined 49 controlled trials with 1,863 participants who trained with resistance training for at least 6 weeks. Protein supplements increased lean body mass by an average of 0.30 kg and maximal strength by 2.49 kg more than control groups. But the important finding for our purposes is the breakpoint: beyond a total protein intake of about 1.6 grams per kilogram per day, no additional gain in lean mass was found.

The implication for mass gainers: the protein in them is only useful for reaching the daily target. Someone who already eats enough protein gets mainly carbohydrate calories from a mass gainer. Protein is not the reason to buy a mass gainer, calories are the reason.

Study 4: Kreider et al. 1996, the direct trial on mass gainer powder

This is one of the few trials that tested a classic mass gainer directly. Richard Kreider and colleagues from the University of Memphis published in the International Journal of Sport Nutrition a double-blind trial with 28 trained strength men who received one of three powders: maltodextrin (carbohydrate only), Gainers Fuel 1000 (a classic calorie-dense mass gainer), or Phosphagain (a lower-calorie formula that also contained creatine).

The results: weight increased in all groups, and body mass increased more in the mass gainer group and the Phosphagain group. But in the classic mass gainer group, fat mass and body fat percentage increased significantly, while a greater increase in lean tissue was found only in the Phosphagain group, the one that contained creatine. There are important caveats here: the study is old and small, the successful formula contained several ingredients so it's impossible to isolate the effect of each one, and one of the study's authors, Anthony Almada, was one of the developers of Phosphagain and a co-founder of EAS, the company that marketed it. And still, the lesson fits all the other evidence: a calorie-dense mass gainer increased weight, but a significant portion of the gain was fat.

Study 5: Levine et al. 1999, why some people "don't gain"

If you've ever wondered why your friend gains weight just from looking at cake and you don't, a classic trial by James Levine and colleagues from the Mayo Clinic, published in Science, provides part of the answer. 16 non-obese volunteers ate 1,000 calories per day above maintenance for 8 weeks. About two-thirds of the increase in daily energy expenditure came from an increase in non-exercise activity thermogenesis (NEAT): small movements, posture, and daily activity we're not aware of. The changes in NEAT explained 10-fold differences in fat storage between participants.

The study examined fat storage and not muscle building, but the message for hardgainers is important: you're not imagining it. There are people whose bodies "burn" part of the surplus through unconscious movement. So there's no point in guessing: weigh yourself once a week, and adjust the amount based on what the scale actually does.

Mass gainer or homemade shake?

If a mass gainer is mostly powdered food, the obvious question is: why not just make liquid food at home? The answer is that it's usually possible, and cheaper. Here's a simple homemade shake:

• 400 ml 3% milk: about 240 calories, about 13 grams of protein
• One medium banana: about 105 calories
• Half a cup of oats (about 40 grams): about 150 calories, plus fiber
• One tablespoon of peanut butter (about 16 grams): about 95 calories
• One scoop of whey protein powder (about 30 grams): about 120 calories, about 24 grams of protein

The total: about 700 calories, about 45-50 grams of protein, and about 80 grams of carbohydrates, very close to a moderate mass gainer serving, only with more fiber, more vitamins and minerals from the food itself, and usually at a lower cost. Tips: grind the oats into powder first so the shake is smooth; each additional tablespoon of peanut butter adds about 95 calories; and anyone sensitive to lactose can switch to lactose-free milk or soy milk. The only downside: you need a blender and 3 minutes, and it's less convenient to carry to work.

Three popular mass gainers: a comparison

For those who still prefer a ready-made powder, here's a comparison between three well-known products. The data are for one serving according to the manufacturer, and the protein percentage is calculated from the calories:

How to choose? If you're missing a few hundred calories per day, the moderate option, or half a serving, is definitely enough and maintains a better protein ratio. The mass gainers of about 1,250 calories are suitable only for those who, even after adding meals, are still very far from the target, and in them about 80% of the calories are carbohydrates. In any case, start with half a serving, and check whether the product already contains creatine before you add more. To compare prices, compare by price per 1,000 calories and not by price per bucket.

Should you take a mass gainer?

Here's where the yellow rating comes in. A mass gainer is not dangerous for most healthy people and is not a "scam," but it's also not a supplement that builds muscle. It's convenient food with several real limitations:

• It's food, not a miracle cure: everything a mass gainer does can be achieved from regular food or a homemade shake.
• Processed carbohydrates and little fiber: most of the calories come from maltodextrin, a carbohydrate that raises blood sugar quickly and doesn't provide the fiber and micronutrients found in real food.
• It's easy to exceed the surplus: a full serving of a heavy mass gainer can by itself exceed the entire recommended daily surplus, and according to the evidence, too large a surplus adds mostly fat.
• Digestive discomfort: very large servings at once, together with lactose and a large amount of carbohydrates, cause bloating, gas, and diarrhea in some people. The solution: start with half a serving and split it throughout the day.
• Creatine duplication: some mass gainers already contain creatine. If you also take creatine separately, you're probably paying twice for the same ingredient for no reason.
• Cost: a homemade shake is usually cheaper per 1,000 calories.

When does a mass gainer make sense? When you're skinny and training, you've already tried adding meals and snacks, and you still can't reach the caloric target due to weak appetite, a busy schedule, physical work, or high training volume. In that situation, a moderate serving per day is a convenient way to close the gap.

Who should not use a mass gainer?

• Diabetes, prediabetes, or insulin resistance: a single serving can contain 85-250 grams of carbohydrates, most of them fast. That's a large sugar load. Consult your doctor or dietitian before any change.
• Overweight: if the goal is to build muscle when there's already excess fat, there's no need for a large caloric surplus. It's better to focus on strength training and enough protein, and regular protein powder is more suitable than a mass gainer.
• Kidney disease: large amounts of protein, and in some products also creatine, require a doctor's approval.
• Lactose sensitivity or milk allergy: many mass gainers are based on milk proteins. Check the ingredient list.
• Unexplained thinness or weight loss: if you're underweight without a clear reason, or you've lost weight unintentionally, you first need to find out with a doctor what the cause is, and only then add calories.
• History of eating disorders: intentional weight change should be done with professional supervision.
• Teenagers: it's better to start with real food, regular meals, and a homemade shake, and if needed with a dietitian's supervision.

What should you take from the research?

1. Target first, product second: calculate how many calories you need. Our free muscle gain planner calculates a caloric target, builds an hourly meal schedule, and a training plan. Aim for a surplus of about 10-20% and a gain of about 0.25-0.5% of body weight per week.
2. Protein in the right amount: 1.6-2.2 grams per kilogram per day, divided into 3-6 meals. Our protein calculator will calculate the exact range for you. Beyond that, more protein doesn't add muscle.
3. Progressive strength training: at least 3 workouts per week with gradual increases in weights or reps. Without this signal, most of the surplus goes to fat.
4. Food first: add a meal or a snack, and make a homemade shake. Only if you still don't reach the target is a mass gainer a convenient option.
5. If you choose a mass gainer, do it carefully: start with half a serving, split it throughout the day, check whether it contains creatine, and weigh yourself once a week. If you're gaining more than about 0.5% per week and your waist circumference is growing quickly, reduce the amount.

Want to know which supplements actually promote muscle building, honestly rated according to the evidence? Run our personal supplement checker with the muscle goal, and get a list tailored to your age, gender, and goals.

The broader perspective

A mass gainer is a good example of how packaging changes perception. When it's in a bucket with the word MASS on it, it looks like a sports supplement. When it's in a blender with a banana and oats, it's clear that it's food. As far as the body is concerned, there's no fundamental difference: calories are calories, and muscle is built only when there's a reason to build it.

The broad lesson is simple: quality mass is built slowly, from a moderate surplus, from sufficient protein, and from consistent training, not from a few thousand liquid calories. Whoever looks for a shortcut in a bucket will get mainly weight, and a large part of it fat. Whoever builds an organized plan will get muscle. If you want to start right, build yourself a plan in the muscle gain planner: caloric target, hourly meal schedule, and a training plan, for free. A mass gainer can help close a gap, but the plan is what builds the muscle.

Medical note: The information in this guide is general and is not personal medical or nutritional advice. If you're underweight without explanation, you've lost weight unintentionally, or you have diabetes, kidney disease, or another medical condition, consult a doctor or dietitian before starting a mass gainer or significantly increasing your calorie and protein intake.

References:
Iraki J, Fitschen P, Espinar S, Helms E. Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review. Sports (Basel). 2019;7(7):154.
Helms ER, Spence AJ, Sousa C, et al. Effect of Small and Large Energy Surpluses on Strength, Muscle, and Skinfold Thickness in Resistance-Trained Individuals: A Parallel Groups Design. Sports Med Open. 2023;9(1):102.
Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384.
Kreider RB, Klesges R, Harmon K, et al. Effects of ingesting supplements designed to promote lean tissue accretion on body composition during resistance training. Int J Sport Nutr. 1996;6(3):234-246.
Levine JA, Eberhardt NL, Jensen MD. Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science. 1999;283(5399):212-214.
Slater GJ, Dieter BP, Marsh DJ, Helms ER, Shaw G, Iraki J. Is an Energy Surplus Required to Maximize Skeletal Muscle Hypertrophy Associated With Resistance Training. Front Nutr. 2019;6:131.