Why Do Meal Replacement Shakes Make Me Nauseous?

By Matt Smith

Published: April 8, 2025

Adjusting to a new diet can always be difficult during the first week or so, but sometimes the problems can persist. A common question is, “why do meal replacement shakes make me nauseous?” This article will help you to find out why.

There are many reasons why a meal replacement shake may cause nausea. One common cause is the use of artificial sweeteners. Finding shakes that are free from artificial sweeteners can help many people to avoid nausea.

Let’s take an in-depth look at what the common causes of nausea are, how some meal replacement shakes may cause them, and how to prevent nausea while enjoying meal replacement shakes.

What is Nausea?

Nausea is defined as a feeling of sickness that could lead to vomiting and an upset stomach. Nausea has a biological purpose, working as a form of defence against foods and substances that are harmful. Swallow a lot of poison, and your body will try to induce vomiting as a way to protect you.

Nausea is caused by the activation of receptors in your brain by neurotransmitters such as dopamine [1]. What causes the influx of neurotransmitters to those receptors can vary. Below is a list of some of the most common causes of nausea.

What are Common Causes of Nausea?

When you drink a meal replacement shake and feel nauseated, the obvious conclusion is that the shake itself is responsible. This is, of course, possible, but it may be another factor that is being overlooked. For example, if you were drinking your meal replacement shake on a rollercoaster, it may not be the shake that is the issue!

Motion Sickness

When walking at a normal pace, your body is constantly receiving signals about your surroundings. These signals help to inform your brain about what is happening. When you travel in a vehicle or a rollercoaster, the signals sent to your brain start to become confused. Your body has no idea whether you are moving or staying still.

This is why it is possible to get motion sickness while sitting at home watching the television or playing computer games. The same issue occurs. Your brain struggles to work out whether you are moving or stationary. Motion sickness can cause nausea, vomiting, anxiety, and perspiration [2].

Food Poisoning

If your body discovers that the food you have eaten is bad for you, it can send signals to the brain that you need to vomit. This can cause nausea, particularly if you try to prevent yourself from vomiting. Food poisoning-induced nausea is very different to motion sickness-induced nausea, as it is purposeful rather than the effects of the brain becoming confused.

Pregnancy

The cause of nausea during pregnancy is a hormone produced in the placenta called human chorionic gonadotropin (HCG). Women with higher levels of HCG tend to have worse morning sicknesses but also have a lower risk of miscarriage [3]. Other hormones, such as estrogen and progesterone, can also cause nausea and sickness.

Dehydration

Being severely dehydrated can really affect how your body functions, and it can affect your brain in a similar way to motion sickness, causing confusion and then triggering the receptors that cause nausea. Vomiting when dehydrated is a common response but also a particularly dangerous one, as you can lose even more water this way.

Medication

Medicine is crucial for your health and well-being, and there are many forms of medication that can help to reduce nausea. However, there are many medicines that can actually cause nausea. Chemotherapy is well-known for causing nausea but is obviously a crucial treatment for people with cancer.

Infections

Infections, particularly those that affect the digestive system, are well known for causing nausea. Influenza, for example, can cause nausea and vomiting in sufferers.

Alcohol

Alcohol causes nausea by irritating the stomach lining. It can also cause motion sickness and dehydration, both of which can cause nausea. Hangovers are famous for causing nausea; this is mostly due to dehydration from the night before.

Why Do Meal Replacement Shakes Make Me Nauseous?

If you have eliminated all other causes, and you are sure that your meal replacement shake is causing you to feel nauseated, then it is useful to identify why this may be.

They May Contain Dairy

Many meal replacement shakes use dairy as their main source of protein. This is often in the form of whey protein, but sometimes casein is used. Whey has many advantages. It is easily absorbed, cheap to use, and provides a delicious taste and texture.

However, many people may suffer from lactose intolerance, which can cause bloating, an upset stomach, and nausea. Whey contains lactose and is, therefore, likely to cause nausea in people who cannot tolerate it.

Many people also suffer from milk allergies, which differ from lactose intolerance, but can also lead to bloating, constipation, upset stomachs, and nausea.

If you are lactose intolerant or have an allergy to milk and dairy products, then make sure that your meal replacement shake does not use whey, casein, or any other form of milk protein in its formula.

This also affects protein shakes. Check out our article on them here.

They May Contain Allergens

But it isn’t just milk allergies that can cause nausea. Many allergies can elicit similar responses. Soy is a very common ingredient in meal replacement shakes, and it can cause a whole host of symptoms: stomach cramps, indigestion, diarrhoea, nausea, and in severe cases, it can cause anaphylaxis and death.

Some meal replacement shakes contain ingredients such as dextrose, which can cause nausea in some people. Maltodextrin and isomaltulose can also cause nausea and can be found in many low-priced meal replacement shakes.

Of course, almost every food on earth has at least a few people who are allergic to them, but some ingredients (soy, maltodextrin, etc.) tend to have larger numbers of people who cannot tolerate them. They also happen to be cheap and low in quality, making their inclusion all the more baffling.

Unlike many companies, Rootana has a completely transparent nutrition label. Check out all the ingredients here.

They May Contain Artificial Sweeteners

Many meal replacement shakes use artificial sweeteners as a way to keep the calorie content low while still delivering a very sweet taste. There are different types of artificial sweeteners out there:

Sucralose
Stevia
Aspartame
Saccharin
Sugar alcohols
Xylitol
Sorbitol

While there are many people who have no reaction to artificial sweeteners, there is a growing number of people who experience mild side effects such as upset stomachs, bloating, nausea, and even vomiting when they come into contact with certain artificial sweeteners and sugar alcohols.

Even if you have no allergy to these ingredients, many of them are known to affect your digestion and cause nausea. Sugar alcohol such as xylitol and sorbitol are particularly renowned for this.

Why You Should Make the Switch to Rootana

Rootana is a meal replacement shake with a difference. It offers all the benefits that many other meal replacement shakes offer (high in protein, high in fibre, packed full of vitamins and minerals), but it also avoids the use of artificial sweeteners as well as cheaper ingredients such as whey protein, soy, and highly-processed carbohydrates such as isomaltulose, dextrose, and maltodextrin.

This means that your risk of nausea is lower with Rootana than with other brands. Rootana gets its sweetness from naturally occurring coconut sugars and uses the finest ingredients to provide you with a delicious, nutritious meal replacement.

Check out our article on the health benefits of Rootana to learn more about this.

Final Thoughts

There are many causes of nausea, and most of them can be traced back to your regular lifestyle. However, if you are wondering, “why do meal replacement shakes make me nauseous?” it could be down to poor-quality ingredients or personal allergies.

Finding the perfect meal replacement shake for you is about many things: taste, macronutrient content, micronutrient content, texture, and how it fits into your health and lifestyle goals. We believe that Rootana delivers on all of these without any of the side effects that so many meal replacement shakes overlook.

References

[1] https://daily.jstor.org/why-do-we-get-nauseated/

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4112051/

[3] https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/nausea-during-pregnancy/faq-20057917

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Complete Nutrition: Perfect Balance of Macros, Vitamins & Minerals

Rootana is a perfectly balanced combination of complex carbohydrates for slow energy release, the right amount of protein for a balanced meal and all 27 vitamins and minerals.

No Half Measures: 400 Calories Per Serving

Many meal shakes are simply too low in calories and too high in protein to be a complete meal, meaning they're little more than a protein shake. Rootana fuels you effectively and has the perfect macro split for a balanced meal.

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No Sweeteners: No Stevia, No Sucralose, No Aspartame, No Acesulfame K, No Monk Fruit

We don't include any sweeteners as they don't provide any nutritional benefit and may have short or long-term unwanted effects. Rootana is naturally flavored with a small amount of coconut sugar.

Tastes Like Real Food: Because It Is Real Food

With no sweeteners like acesulfame k, aspartame, stevia or sucralose (Splenda), Rootana tastes like real food. That means no artificial after taste and none of that bloated feeling that many sweeteners cause.