How to Use a Mass Gainer for Weight Gain

If you’re training hard but the scale won't budge, the problem often isn’t your workout. You may simply not be eating enough calories consistently to gain weight. This is where I think mass gainers can be useful.

I don’t see a mass gainer as a shortcut to building muscle. It’s basically a convenient way to add a large amount of calories, carbohydrates and protein to your diet when getting those calories from regular meals becomes difficult. You can drink all the mass gainer you want, but if your overall diet, training, and recovery aren’t supporting muscle growth, the shake itself won’t magically build muscle.

In this guide, I’ll show you how I recommend approaching a mass gainer, including how much to take, when to take it, what to mix it with and how to tell if you actually need one.

What Is a Mass Gainer?

A mass gainer is a high-calorie supplement designed to make it easier to consume enough calories and protein to gain weight. Most mass gainers combine:

• Protein
• Large amounts of carbohydrates
• Some dietary fat
• Vitamins, minerals or other added ingredients depending on the formula

The biggest difference between a mass gainer and a regular protein powder is the calorie content. A whey protein shake might give you roughly 100–150 calories per serving. A full serving of some mass gainers can provide several hundred calories, or even more than 1,000, depending on the product and serving size. That can be extremely helpful if you’re already eating three or four solid meals and still struggling to get enough food down. It can also be completely unnecessary if you’re already eating enough.

How Do You Use a Mass Gainer to Gain Weight?

The most important thing I want you to understand is this:

Use a mass gainer to fill the gap between the calories you can comfortably eat and the calories you need to gain weight.

Don't automatically start with the maximum serving printed on the tub. If a serving contains 1,000 calories and you only need another 300 calories per day, drinking the full serving may just push your calorie surplus much higher than necessary. Instead, figure out roughly how much you’re currently eating and watch what happens to your body weight over time. If your weight stays relatively unchanged for several weeks, you probably need more calories. That’s where you can introduce a partial serving of mass gainer.

A Simple Starting Approach

If you’re using a mass gainer for the first time, I recommend keeping it simple:

1. Continue eating your normal meals.
2. Start with around half of the manufacturer's recommended serving.
3. Drink it once per day.
4. Track your body weight consistently.
5. Adjust your serving based on your progress.

You don't need to overhaul your entire diet because you bought a mass gainer. You’re just adding calories where you need them.

How Much Mass Gainer Should You Take Per Day?

No single serving size works for everyone. The right amount of mass gainer is the amount that helps put you into a manageable calorie surplus without replacing nutritious whole foods or causing unnecessary digestive issues. Your needs depend on things like:

• Your current calorie intake
• Your body size
• How active you are
• How frequently you train
• Your appetite
• The calorie content of the mass gainer

This is also why I don't love advice like “take two scoops every day.” Two scoops of one product could contain 300 calories. Two scoops of another could contain 800. Look at the actual nutrition label and calories per serving, not just the number of scoops.

Start With a Partial Serving

Mass gainers can be heavy. If you go from never drinking one to suddenly throwing a huge serving into a blender with milk, peanut butter and oats, your stomach may not be particularly happy with you. Start with half a serving to see how you tolerate it. If your digestion feels good but your weight still isn't increasing after a couple of weeks, you can gradually increase the amount.

When Is the Best Time to Take a Mass Gainer?

For gaining weight, your total daily calorie and protein intake matters more than drinking your mass gainer at one exact time. That said, there are a few times when I think it makes the most practical sense.

After Your Workout

Post-workout is probably the easiest time to work a mass gainer into your routine. You’ve finished training, you need to recover, and a shake gives you a convenient combination of carbohydrates, protein and calories. If you already drink a protein shake after training, replacing it with an appropriately sized mass gainer serving can be an easy change when you’re trying to bulk.

Between Meals

This may actually be the better option if appetite is your biggest problem. Instead of making lunch or dinner enormous, have a shake between meals. For example:

Breakfast → mass gainer → lunch → snack → dinner

You’re increasing your total daily calories without trying to force another huge plate of food into one meal.

Before Bed

You can also take a mass gainer later in the evening if that’s when you realize you’re short on calories. I wouldn't force yourself to drink a huge shake immediately before lying down, especially if it affects your digestion or sleep. Again, timing should work around your routine, not control it.

Should You Take Mass Gainer on Rest Days?

Yes, you can. One mistake I see with bulking is treating calories like they only matter on workout days. Your body is still recovering between training sessions, and muscle building doesn't happen only during the hour you’re lifting weights.

If you need extra calories to maintain your calorie surplus, you can keep using a mass gainer on rest days. You also don't necessarily need the exact same serving every day. If you naturally eat more food on a rest day, you may need less mass gainer. That’s why I prefer thinking about your total diet instead of following a rigid supplement schedule.

Should You Mix Mass Gainer With Water or Milk?

Both work.

Mix It With Water If:

• You want fewer calories
• You prefer a thinner shake
• Milk bothers your stomach
• Your mass gainer already provides plenty of calories

Mix It With Milk If:

• You need additional calories
• You want more protein
• You prefer a creamier shake
• You tolerate dairy well

Milk can turn an already calorie-dense mass gainer into an extremely high-calorie shake, so check the numbers. That's useful when you genuinely need those calories. It's unnecessary when you don't.

How I Would Build a Higher-Calorie Mass Gainer Shake

If you need even more calories, you can build around your mass gainer rather than just adding more powder. For example, you could blend it with:

• Milk
• Banana
• Oats
• Peanut butter or another nut butter
• Greek yogurt
• Frozen berries

This also lets you bring more whole foods into the shake. A banana, oats, milk, nut butter and mass gainer can quickly become a very calorie-dense meal. That’s great for someone who genuinely struggles to eat enough. Just remember that adding more ingredients means adding more calories. Don't fall into the trap of thinking that because the ingredients are nutritious, the calories somehow don't count.

Will a Mass Gainer Make You Gain Muscle or Fat?

Potentially both. A mass gainer provides calories. It doesn't determine where every calorie goes. If you're progressively strength training, eating enough protein, and maintaining a reasonable calorie surplus, you're creating a much better environment for muscle growth.

But pushing your calories far above what your body needs doesn't automatically mean more muscle. Some of that additional weight can be body fat. That's another reason I prefer gradually increasing calories instead of immediately taking the largest mass gainer serving possible.

How Fast Should You Gain Weight With a Mass Gainer?

Don't judge your progress from a couple of days on the scale. Your body weight naturally changes based on food intake, hydration, sodium, carbohydrate intake and digestion. Instead, weigh yourself under similar conditions and look at the trend over several weeks.

If you're consistently gaining weight and your gym performance is progressing, you probably don't need to keep increasing your mass gainer serving. If your average weight isn't moving after a few weeks, increase your calorie intake slightly and continue monitoring. A mass gainer is simply one way to make that adjustment.

Do You Actually Need a Mass Gainer?

Before buying one, ask yourself:

Am I struggling to gain weight because I genuinely can't eat enough calories?

If yes, a mass gainer can make your life much easier. I think they're particularly practical for someone who:

• Has a naturally smaller appetite
• Burns a lot of calories through work, sports or training
• Has difficulty eating large meals
• Needs convenient calories during a busy day

• Has repeatedly struggled to maintain a calorie surplus

But if you can reach your calorie target through regular meals without feeling like you're force-feeding yourself, you don't need a mass gainer. Whole foods should still make up the foundation of your diet.

Common Mass Gainer Mistakes I Would Avoid

Taking the Full Serving Immediately

A massive serving isn't automatically better. Start smaller and increase it when your progress tells you to.

Replacing Too Many Meals

A mass gainer is convenient, but I wouldn't build your entire diet around powdered calories. Use it alongside your regular meals.

Ignoring the Nutrition Label

Compare calories, protein, carbohydrates, serving size and ingredients between products. “Two scoops” tells you almost nothing without context.

Expecting the Shake to Build Muscle for You

You still need progressive strength training, adequate recovery, protein and consistency. A mass gainer simply helps you eat enough to support that process.

Increasing Calories Every Time the Scale Stalls for a Few Days

Weight fluctuates. Look at trends across weeks before making major changes.

Frequently Asked Questions About Mass Gainers

How many times a day should I take mass gainer?

For many people, one serving or partial serving per day is enough. If you need a lot of extra calories, splitting the serving into two smaller shakes can be easier to digest.

Can beginners use mass gainer?

Yes. A beginner can use a mass gainer if they struggle to consume enough calories through food. I would start with a partial serving rather than immediately using the maximum amount on the label.

Can I take mass gainer without working out?

You can, but a mass gainer simply increases your calorie intake. If your goal is muscle gain, combine your calorie surplus with resistance training rather than relying on the supplement alone.

Can I take mass gainer every day?

Yes, including rest days, if you need those calories to meet your daily intake. Your serving doesn't have to be identical every day.

Is mass gainer better before or after a workout?

Neither timing is mandatory. Post-workout is convenient because you can combine calories, protein, and carbohydrates with your recovery meal, but your overall daily nutrition matters more than exact timing.

How long does it take for mass gainer to work?

A mass gainer starts adding calories to your diet immediately, but judge meaningful weight gain over weeks rather than days. If your average body weight isn't increasing after consistently eating more calories, reassess your total intake.

My Take on Using Mass Gainer for Weight Gain

I think mass gainers make the most sense when you stop treating them as a muscle-building shortcut and start treating them as what they actually are: a convenient source of calories and protein. If you're already training consistently and eating well but simply can't consume enough food to move the scale, they can be incredibly practical.

Start with a smaller serving. Keep eating real meals. Track your weight.  Keep progressing in the gym. Then adjust your intake based on what your body is actually doing rather than blindly following the biggest serving listed on the tub.

If you're looking for one, you can also browse the mass gainers available on Fit Fuel Blog and compare the calories, protein and serving sizes to find one that fits your own calorie needs.

About the Author

I created Fit Fuel Blog to share practical fitness and supplement information based on my own experience with training, nutrition and the products that come with that lifestyle. I’m not interested in telling you that you need every supplement on the shelf. My goal is to break down what a product actually does, where I think it can be useful and where your training, nutrition and consistency matter more.

When I write about supplements like mass gainers, I look at them the same way I do for my own fitness: does this actually solve a problem, and does it help you stay consistent? The information on Fit Fuel Blog is educational and based on personal experience and research. It is not a substitute for individualized medical or nutrition advice from a qualified healthcare professional.