What Are the Side Effects of Meal Replacement Shakes? Safe?

Meal replacement shakes are a great way to eat healthy and balanced meals on the go. In the current lifestyle where time is of the essence and we are constantly in the move, meal shakes can offer a nutritious meal that adapts to your needs. But what are the side effects of meal replacement shakes? Are they safe to consume? And what should you look out for?

After having consumed meal replacement shakes for the past 5 years, and having interacted with thousands of meal shakes consumers, I am glad to say that meal replacement shakes do not have any major side effects. In fact, they are mostly beneficial, and 82% of the consumers that drink meal shakes regularly are happy with what they get from them.

However, there are some possible meal replacement shakes side effects like:

  • Bloating and excessive gasses
  • Smelly farts
  • Nausea
  • Weight loss
  • Digestive discomfort

On top of that, the best meal replacement shakes that fit your diet should enhance your nutrition and health, not hinder it. So make sure you find a meal shake that fits your needs.

What Are the Most Common Side Effects of Meal Replacement Shakes?

As mentioned above, most of the side effects of meal replacement shakes are related to digestion issues and stomach discomfort. It’s a lot more rare to suffer from stronger side effects like nausea or headaches, and this is often caused by an allergen or an ingredient that your body doesn’t react well, too.

In extreme situations, meal replacement shakes can cause your acne to blow, or for you to feel weak and without energy. The latter is probably related to not consuming enough calories.

Bloating and Smelly Farts

The most common side effect of meal replacement shakes for first time users is bloating and excess of gasses.

This is because meal replacement shakes are rich in soluble and insoluble fiber that is fermented by your gut bacteria in the intestine. There’s nothing wrong with this as fiber acts as prebiotic promoting healthy gut bacteria. In turn, keeping your gut bacteria happy is extremely important as they help you with digestion, neurotransmitter synthesis, repairing your intestinal mucus, and in many other vital processes.

meal replacement shakes side effects
I’ve been consuming meal replacement shakes for 5+ years without any health issues or side effects.

The downside is that if you are not used to consuming prebiotic fiber, your stomach will “fight” against you. During the first 2 weeks you might suffer from excessive gasses and some bloating.

In fact, the popular meal replacement brand Huel is known for causing these side effects, and many make jokes about the “Huel farts”.

Since I began drinking Huel , My fart levels have increased ten fold.

u/shhsfootballjock, on Reddit

I had some extra farting and loose movements for the first week or so but it settled down. No issues now, but I only regularly have Huel for breakfast (and a sporadically for a few other meals).

mollymoo, on Reddit

Note: some people found that having digestive enzymes, or starting with smaller servings helped with their issues.


In rare occasions, some users might feel nausea after consuming meal replacement shakes. While this is extremely rare, it’s most likely because there’s an ingredient that your body is not used to or does not agree with.

Among the common ingredients that could cause this are soy, milk, and ashwagandha (rarely added). Those meal replacement shakes that use more wholefood ingredients, like Ka’chava, might have some mushrooms or vegetables like Reishi that could cause adverse effects.

Headaches and Migraines

This is another side effect caused by meal replacement shakes that is highly unlikely. However, there are people who react negatively to sucralose and aspartame. These sweeteners are widely used in the industry and could cause and adverse reaction.

If you are one of these, you should look for meal replacement shakes without artificial sweeteners.

Weight Loss

Even though for many weight loss will be a godsent gift, for a few consumers it could be a negative side effect.

Meal replacement shakes can be quite filling and could cause you to eat less calories than what you are used to. Consequently, it could lead to a gradual weight loss if you don’t adjust your calorie intake accordingly.

Allergens: Dairy, Soy, Gluten, Nuts

Lastly, meal replacement shakes can include a lot of allergens. The above-mentioned are among the most common ones.

In fact, finding a gluten-free meal replacement shake can be a challenge as most brands used oats that could be cross-contaminated.

Similarly, you will have to look at the allergens for dairy, as milk-derived particles like lactose can create serious discomfort, flatulence and bloating. Nonetheless, dairy-free meal replacement shakes exists, and there are also a ton of hypoallergenic options.

Myth Busting: You Need to Chew Your Meals

One of the most common misconceptions about meal replacement shakes is that they will cause your jaws to weaken as you don’t need to chew.

While chewing is a vital part of the digestive process, there are no studies showing that consuming your shakes will weaken your jaws.

There are some reasons why chewing is important, such as, helping you break down your food smaller sizes that fit in your digestive track, and help you produce digestive enzymes to help the process. Some studies even link slower eating and more chewing to appetite reduction.

Plus, if you want stronger jaws, you can always chew a gum according to the latest research.

Are Meal Replacements Safe?

For all intends and purposes and for 95% of the population, meal replacement shakes are a healthy and safe meal option.

There is a wide array of options with different allergens, macronutrient ratios, fiber content etc. that will suit various individuals.

enaut no side effects from meal replacements

Conclusion – What Are the Side Effects of Meal Replacement Shakes?

The most common side effects of meal replacement shakes are bloating, flatulence, nausea, and headaches. In rare occasions, they can also cause diarrhea, constipation, acne, and weight loss. It is also important to notice that meal replacement shakes might contain allergens that could cause an allergic reaction. Please read the label before consuming.

That said, for the majority of population meal replacement shakes are a safe option to have a balanced meal on-the-go or at home. They are convenient, healthy, packed with nutrients and can help you achieve your physical goals.

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