Weight gainer supplements are designed to help you put on pounds by providing you with a higher calorie source.
Also called mass gainers, their caloric content can range anywhere from 250 calories all the way up to 1000 calories or more.
If you’re someone who struggles with gaining weight, this might seem like the ideal solution.
But is it?
In this review, let’s go over some of the need-to-know facts about the best mass gainer supplements so that you can make an informed buying decision that's right for you.
Our Top Weight Gainers (2021 Updated)
1 - Transparent Labs Mass Gainer (Editor's Choice)
This is my personal favorite because of the following reasons:
It contains 750 calories, 53 grams of protein, 12 grams of fat, and 109 grams of carbs per serving, which makes it a reliable mass gainer supplement available on the market to help you build muscle mass and gain weight quickly and effectively.
You can use this mass gainer to make weight gainer protein shakes or even as a meal replacement for muscle building while still getting all the important nutrients you need.
- 750 calories per serving
- Comes in sweet vanilla and cookies and cream flavors
- Easily mixed with water shakes, and smoothies
- No artificial sweeteners, coloring, or preservatives
- Made with 100% grass-fed whey protein concentrate
- The cookies and cream flavor is not gluten-free
On top of that, the Mass Gainer ProteinSeries is made from 100% grass-fed whey protein concentrate and is said to have no artificial sweeteners, colorings, or preservatives.
The cookies and cream option is not gluten-free though, but you can still try the sweet vanilla flavor.
This is why it belongs in our hefty list of best mass gainers today.
2 - Optimum Nutrition: Pro Gainer
Optimum Nutrition (ON) is a brand that many people know and trust, so it should come as no surprise that their mass gainer supplement ranks at the top in our list of recommended products.
Pro Gainer will give you 650 calories per one scoop serving, 8 grams of dietary fat, 85 grams of carbs with 7 of those coming from sugar, and 60 grams of protein in total.
With a right balance of macronutrients, it makes this weight gainer a perfect supplement that can also be used at any point during the day.
You’ll also take in 5 grams of dietary fiber per serving, which will help give you maximum blood glucose control.
ON Pro Gainer also contains a nice blend of whey, casein, as well as egg protein, so this will be a good option for those who tend to struggle with having too much whey protein (lactose intolerant people) in their diet.
- Packed with 650 calories per serving to support weight gain
- Helps boost energy for high-explosive workouts
- Easily mixed with water, shakes, and smoothies
- The unflavored variant does not taste good
3 - Optimum Nutrition Serious Mass
Optimum Nutrition Serious Mass was created as a high-quality mass gainer protein powder for those who want to gain weight.
One serving of Serious Mass will give you 1,250 calories and 50 grams of protein per serving. This muscle gain supplement will help provide you the nutrients needed to gain weight without forcing yourself to overeat.
It also speeds up muscle recovery after intense exercise sessions to get you ready for the next gym day. Packed with 25 vitamins and minerals, Serious Mass helps keep you energized while adding gains.
- Another high-quality weight gainer from ON
- Contains 1,250 calories per serving for better gains
- Speeds up muscle recovery after workouts
- Texture is not really good when mixed with water
You can take this supplement between meals, during post-workout, or before going to bed.
Pro tip: If you want to gain some serious size, mix this with whole milk.
4 - BSN True-Mass
BSN is well-known for its great-tasting protein powders with their meal replacement product Syntha-6 being a bit hit for many. Now, you can get the mass gainer version of Syntha-6 with True-Mass.
This product contains 700 calories per 3-scoop serving and provides you with 17 grams of dietary fat, 90 grams of carbs - 15 of those from sugar and 6 grams from fiber, as well as 50 grams of protein.
This is a higher fat product, so it is a good option later on in the day. Use it at a time other than the post-workout period.
- Contains 700 calories per serving to support weight gain
- Provides 2:1 ratio of carbs and protein
- Tastes great in shakes and smoothies
- Not advisable to take during post-workout
It also contains 10 grams of naturally-occurring branched-chain amino acids (BCAAs), which studies suggest are effective in supporting anabolism and muscle recovery in the body.
5 - CytoSport Cyto Gainer
CytoSport is a name that’s been around for a while. The company makes protein powders, as well as weight gainers. Their Cyto Gainer is a mass gainer supplement that contains a lower overall at just 550 calories per serving.
Of course, you have the option to take half a serving if you want fewer calories.
But per 4-scoop serving, you’ll also take in 5 grams of fat, 73 grams of carbs, 8 of which are sugar, and 54 grams of protein.
- Recommended for those who want to take lighter supplements
- Promotes muscle recovery after high-energy workouts
- Tastes good with whole milk
- We find it hard to mix with other liquid
Aside from the presence of artificial flavors and sweeteners, it is also hard to mix with other liquids so you might have to double your shaking efforts to have a satisfying and smooth drink.
6 - Universal Nutrition Real Gains
Real Gains Weight Gainer makes no bones about the fact that it’s high in carbs.
It's based on the old-school bulk building that focuses on producing large, powerful muscles and leaves any arguments over which diet is better for another day.
The bad news is that this mass gainer supplement has a few artificial ingredients along with sugar and salt (presumably to aid in the taste), but on the brighter side, it definitely works to just do that.
- Contains healthy fats you need for muscle gain
- With regular workouts, you’ll see gains in bulk and strength
- Plenty of calcium to help build a stronger skeleton
- Fairly high in sodium and cholesterol
If the kind of bulk that raises eyebrows is what you’re after, Real Gains will provide it for you. Your job then is to get into the weight room, build muscle, and sculpt that bulk into the body you want.
7 - MuscleMeds Carnivore Mass
If you are really watching your sugar and carb count in your quest for lean muscle mass, you’ll want to consider Carnivor Mass by MuscleMeds.
This mass gainer protein powder is not made from whey, but instead, from beef, so it is free of lactose and is overall, a pure product.
With 0 grams of sugar, it’s one that will keep insulin levels stable, preventing unwanted body mass gain.
This one is also light at just 690 calories per serving, providing 50 g of protein and 119 grams of carbs.
- Made with 100% hydrolyzed beef protein isolate
- Helps build lean muscle mass
- Good for those with sensitive stomachs
- Not vegan-friendly
With only 2 grams of fat, it’s also one that’s a good choice following a workout session.
8 - MuscleTech Mass Tech
Mix a single serving of Mass Tech with a couple of cups of skim milk, and you'll get 1,000 calories and an astonishing 80 g of protein to do with as you wish.
Mass Tech is loaded with the branched-chain amino acids (BCAAs) you need to stimulate muscle protein synthesis and shorten recovery times.
MuscleTech doesn't stop there, however. They go all-in on muscle growth by providing 10 grams of creatine monohydrate per serving as well.
- A generous 17 grams of BCAAs per serving
- One of the few mass gainer supplements and protein powders to include muscle building creatine monohydrate
- A well-balanced combination of slow and fast-digesting proteins
- 80 grams of protein per serving is among the best in class
- Like most protein powders, the taste is only so-so
With Mass Tech, you're likely going to spend less time nursing sore muscles and more time in the gym. And the creatine monohydrate content may help with muscle building too.
Reasons To Take A Weight Gainer
People take these calorie dense drinks because of two reasons:
- They struggle to hit their daily calorie requirement because of their busy lifestyle.
- They're an ectomorph or "hardgainer".
Weight gain protein powders are helpful for increasing calories when you can't increase your calories from food alone.
- Susan Kleiner & Maggie Greenwood-Robinson (Human Kinetics)
What to Look for in a Weight Gainer
- Calorie requirements - Piling up on calories must be challenging just by eating. As an alternative, you can opt for mass gainer supplements to bulk up and meet your daily calorie requirements. Look for a meal replacement that can supply more than 450 calories in one serving to maximize your gains.
- High-quality protein (whey or casein) - One of the most important things to consider in finding the best mass gainer supplement is the quality of protein used. The considered best types of protein are casein and whey, for muscle development, since they contain all the essential amino acids needed by the body. The only difference between the two is the rate of digestion, where whey is more quickly absorbed by the body compared to casein.
- Carbohydrates - Apart from knowing your protein source, carbohydrate content is also a vital thing to consider. It's the body's primary source of energy during exercise and strenuous physical activity, so a good amount of carbs won't only fuel your performance, but will also ensure weight gain.
- Ingredients - Knowing how to read the food label gives an assurance that you get what you pay for. It also protects you from consuming ingredients that are not good or healthy for the body. Understanding the macronutrients (and micronutrients) on your favorite supplement is essential when planning your diet.
- Serving size - As long as you get enough calories, serving size shouldn't be an issue at all. However, some mass gainer supplements come at a whopping 6 scoops of powder per serving (or more), which may make them difficult to drink or even blend. An average of 1-3 scoops per serving should be ideal for giving you the right amount of calories, vitamins and minerals while still being easy to ingest.
Studies have shown that ingesting casein and whey (which most weight gainers have) results in net anabolism and muscle growth following exercise.
See related post:
How Much Weight Gainer Should I Drink?
Generally speaking, one serving of a weight gainer will be enough for most people.
This will, however, depend on the calorie content of the drink and how fast your individual metabolism is. 
What you should aim to do is match the weight gainer to your metabolic level. If you are a pure ectomorph and really struggling to increase your weight, you’ll want to look for a product that has 500+ calories per serving.
If you are someone lives a very active lifestyle and burns a lot of energy but gains fat if they aren’t careful, then a weight gainer in the 250-400 calorie range is more appropriate to support enhanced muscle endurance and growth.
Weight Gainer Side Effects
Generally speaking, as weight gainer is quite similar to a standard protein powder, you won’t be at risk for any extra symptoms over and beyond what you would with the standard protein powder.
- Bloating and/or digestive issue - Some people may experience bloating and/or gas when using mass gainer, in part due to the lactose (if not having lactose free weight gainer), as well as simply due to the sheer calorie count. To avoid this, consider working your way up. Try a mass gainer that has around 250-300 calories, then 450 calories, then the 600 calorie level and s
- Fat gain - Remember, your body can only build so much muscle at once. Any excess calories beyond this point will be converted into body fat. This is why more is not always better and why you shouldn’t go out and find the weight gainer with the highest calorie value thinking it will yield optimal results.
Mass gainers can cause body fat gain. Many people taking mass gainers tend to assume that all the excess calories will automatically turn into muscle. But they will also turn into adipose tissue (unless the person taking it is burning more calories than they are consuming).
- Peter Tzemis, Nutritionist
Who Should Drink Weight Gainers?
Weight gainers or mass gainers are for people that struggle to gain any weight - people who are naturally thin and who have the ectomorph body type.
Mass gainer supplements may also be used by athletes who are expending a very high amount of energy on a day to day basis and need the extra calorie support.
A good rule of thumb is that if your daily calorie needs are higher than 3000 per day, looking into a weight gainer is a smart move. Eating more than 3000 calories per day from whole food sources can be hard to stomach, which is where a mass gainer comes in handy.
When Should I Drink My Mass Gainer?
You should drink your mass gainer post-workout so your muscles can soak up all the nutrients, vitamins, minerals, and essential amino acids to aid in your recovery.
However, you can always drink it for breakfast, between meals (as a snack), and before going to bed. You can mix mass gainers with water in your shaker, or if you want to add more calories, you can add milk.
If the texture is too thick, you can use a blender to get a better consistency. See more information on How to use mass gainers in this related post.
Can I Use A Mass Gainer Before My Workout Session?
You may drink mass gainers before a workout, but you may notice you feel bloated and/or sluggish during the workout if you take it prior to hitting the gym.
For more efficient results, try using it after your workout or at another point during the day.
Should I Take My Mass Gainer With Food?
While you can do this, remember that weight gainer supplements are very calorie-dense, and taking it with food may cause even more bloating to occur. Your best bet is to take it as a snack or at a different time than your main meals.
Can I Take It On Days I Don't Train In The Gym?
You can if it helps you reach your calorie intake needs. Remember that your calorie intake may not be as high on non-training days, so you need to adjust your intake accordingly.
You may decide to only take half the serving size on non-training days as an easy way to achieve better calorie control.
The Best Weight Gainer Is...
The best mass gainer protein powder not only helps with weight gain and muscle growth, but also contains the essential vitamins and minerals and skips the unhealthy ingredients to achieve a good overall health.
That's what you're likely going to get with the ProteinSeries Mass Gainer from Transparent Labs if you consider this product.
With this high protein content, this mass gainer will optimize your results, helping you gain muscle and weight.
Since it comes from 100% grass-fed whey protein concentrate, you would be assured that the calories you are consuming are of top quality.
Use it as a high protein shake or a meal replacement. Either way, you can’t go wrong with the ProteinSeries Mass Gainer for the results you want.