Bloating When Taking a Mass Gainer? - Here’s the Solution

James Cunningham, BSc, CPT
Published by James Cunningham, BSc, CPT | Staff Writer & Senior Coach
Last updated: November 28, 2023
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Recently I had a client who wanted to bulk up. He did everything by the book. He started weight-training and eating to achieve his desired body weight.

Then he came to me complaining that he's feeling bloated all the time and wanted to know can anything be done about it.

I've spent countless hours searching for all available information on how mass gainers cause bloating and what can be done about it.

If you're in the same situation, here's some advice that can hopefully help you stop feeling bloated.

Quick Summary

  • To avoid bloating when using mass gainers, gradually adjust to high-calorie shakes and monitor your total daily calorie intake.
  • Excessive caloric intake from mass gainers can lead to bloating; consider reducing shake sizes or caloric content per shake for better digestion.
  • According to a 2015 Springer Link article, sugar alcohols, often present in mass gainers, contain 0.2 to 2.7 calories per gram and can cause digestive issues leading to bloating when overconsumed​.
  • In my professional experience, managing caloric intake from both food and mass gainers is essential to avoid bloating and optimize muscle growth.

How Do Mass Gainers Cause Bloating?

close up image of a man's belly with his hands on it

People who are taking a mass gainer can experience varying degrees of gastrointestinal upset, such as:

  • Bloating
  • Cramping
  • Diarrhea

This happens because to gain weight you need to eat more than you spend.

But, just having a calorie surplus isn’t enough if you can’t eat a meal for another five to six hours.

Amount of Calories

measuring tape wrapping both spoon and fork

In my time as a fitness trainer, I've seen clients overwhelmed by the high-calorie content in some mass gainers.

I remember one who tried consuming 1000 calories in a single shake and ended up feeling uncomfortably bloated.

Through trial and error, we found that starting with smaller portions and gradually increasing them helped his body adjust without the bloating.

Often, there isn’t one specific cause of stomach problems, but the reasons can be varied, such as lactose intolerance or the protein shake volume

Lactose-based Ingredients

butter, milk, cheese and yogurt in one image

You should always check the ingredients of the mass gainer you’re taking.

What can happen is that some brands use less processed and cheaper ingredients.

While this won’t endanger the process of gaining weight, some of these ingredients can have a high lactose concentration.

If you’re lactose intolerant, you want to avoid weight gainers that have a:

  • Milk powder
  • Milk protein concentrate
  • HIgh concentration of whey protein

If you see these, especially the first two, on the list of ingredients, it’s a sign that the product has a high amount of lactose.

Be careful with whey proteins, as it has enough lactose to make lactose intolerant people feel bloated.

The solution for this is to use whey isolate because isolate is more refined, has less lactose, and more protein per gram.

"The problem is that not all whey protein is created equal. Some are made from concentrates, which are high in lactose. I recommend whey protein isolate because it has less lactose, which your body might digest more easily."

- Sameer Islam, MD

Time of Consumption

woman chugging a jug after workout

Another good tip is not to have whey immediately after a workout, but wait between 15 minutes to half an hour and drink it sip by sip.

If you’re drinking whey with milk, switch to water instead.

Some people feel bloated because the protein supplement and carb ingredients, such as casein and fructose, move through your digestive tract more slowly and get digested slowly too, which can also make you feel bloated.

A good option here is to use more stomach-friendly ingredients, such as waxy maize starch.

How to Avoid Feeling Bloated When Taking a Mass Gainer?

woman frustrated holding her stomach

Switch Up Your Supplement

Are you feeling tired after you finish the prescribed amount of protein supplement per serving?

This happens because when you consume a huge amount of calories, your body will draw blood from other areas to cope with the amount of food it has to digest.

For example, if you’re feeling sleepy after your mass gainers or protein shakes, it’s a sign that you should try something different.

If commercial mass gainers disagree with you, a good idea is to make your own. Start with a high-quality protein, and add your source of carbs.

See the best mass gainer supplements on the market.

Eat Less Calories

shirtless man holding up a bowl filled with salad

If you aren’t used to eating a considerable amount of calories, you’ll likely feel bloated, especially if you’re taking a mass gainer that requires a large serving size (over 300g).

You don’t want an excessive amount, but enough carbs that won’t make you feel tired, sleepy, and bloated after being consumed.

It’s a good idea to go for a partial serve instead of a full serving.

And, by eating fewer calories in a single meal, you’ll have more energy because the body won’t have to deal with a lot of food at once.

The benefits of eating fewer calories include:

  • Less bloating
  • Not feeling tired
  • Fewer chances of storing fat

Avoid Sugar Alcohol

spoon filled with sugar cubes

Sugar alcohol is neither sugar nor alcohol, but carbohydrates. It’s called sugar alcohol because it looks a little bit like sugar and alcohol.

It’s usually found in chewing gum, plants, protein bars, and lots of processed foods.

“If you abuse it or overconsume it or increase your exposure to it, your likelihood of having adverse effects on your digestion goes up."

- Roger Clemens, Adjunct Professor at the University of Southern California’s International Center for Regulatory Science

Don’t mistake it for artificial sweeteners. Based on a 2015 article published in Springer Link, it has different caloric content. While artificial sweeteners are sugar-free, sugar alcohols have 0.2 to 2.7 calories per gram [1].

Sugar alcohols go to the large intestine, where the gut bacteria metabolize them and release hydrogen gas. This leads to gas, feeling bloated, stomach pain, and even diarrhea.

Drink High Fiber Shakes to Gain Weight and Muscle Mass

jar filled with banana smoothie and a bowl of oats on the side

From my own experience, transitioning to a high-fiber diet using protein and fiber shakes can initially cause bloating and gas.

This doesn’t mean you have to stop drinking protein shakes that have fiber, especially because fiber has many health benefits, such as:

  • Helps you lose body fat
  • Reduces blood sugar spike after a high-carb meal
  • Helps maintain bowel health
  • Lowers cholesterol levels [2]

What you can do until you get used to a high fiber intake is have a quarter of the serving dose on the first day, then a half-serving dose the following day, and so on, until you gradually come to a full protein shakes serving in about a week.

Some good protein shake examples to avoid feeling bloated are:

  • Protein shakes with pineapple juice — blend pineapple with water and whey protein in a blender, and have it within half an hour of your workout. Pineapple has a bromelain enzyme which is excellent if you have digestion problems.
  • Protein shakes with yogurt/curd and banana — Mix yogurt, banana, and whey powder in a blender and drink it after a workout. Yogurt has active bacteria, which help with digestion, and bananas are rich in sugars which is good for post-workout.

Track Diet and Calorie Consumption

empty notebook with diet tools on the side

In my practice, I've noticed that a common mistake is not accounting for the total daily caloric intake, especially when using mass gainers.

For example, you need 4000 calories a day, and you’re already getting 3500 from the food you eat.

Then, you have three weight-gaining drinks of 300 calories each, which brings you above your total needed amount.

Instead, to avoid gastrointestinal issues, you can lower the amount of shakes you have.

For example, instead of each shake being 300 calories, you can lower it to 100, and you’ll end up with your target goal.

How to Make and Drink Mass Gainers Correctly

jar getting filled with a smoothie from a blender

It matters how you blend and drink your mass gainer for better muscle gains and to prevent bloating.

If you blend your shake in a blender and gulp it down in a matter of seconds, you’ll get bloated because the air traps the bubbles.

The longer you blend the shake, the more air goes into it, which means you’ll ingest more air.

Don’t overdo the blending.

You can also open the blender lid after the blending is done and let the shaker sit for about 5 minutes.

Or, if you don’t want to wait, stir the shake with a spoon after you blend it.

Sip it slowly and not in one go.

How to Digest Food Easier While Taking Mass Gainers

crossed fork and knife on an empty ate

You can do several things to digest food more efficiently and avoid being bloated when taking a weight gainer.

  • Be careful with low carb and fad diets, such as a ketogenic diet — According to the article published in Healthline, when you start the keto diet, you’ll go through something called the keto flu, where the body tries to adapt to getting energy from fat, and you can lose fat instead of gaining it [3].
  • Intermittent fasting — Per a 2016 study published in The National Center for Biotechnology Information (NCBI), it will result in weight loss, not weight gain. If you still want to try intermittent fasting, you can try having more calories, especially pre-workouts [4].
  • Choose easy-to-digest food — For example, instead of a steak, eat ground meat because it’s easier to chew and digest and won’t make you feel bloated. If you don’t have problems digesting dairy products, use whey powder instead of protein powder.
  • Be careful with adding fat and carbs — Instead of brown rice, choose white rice if you want to add carbs. Use olive oil for your salad to get enough calories.
  • Use foods that improve digestion — Bananas, onions, yogurt, cottage cheese, greek yogurt.


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