Protein Powder Constipation: Does Protein Powder Cause Constipation?

Written by Carina Fabia

Last updated on: Sep 17, 2022

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Protein shakes are a great way for individuals to increase their protein intake. Sometimes, protein powders can lead to constipation. Normally, constipation is not caused by the protein shake, but from a lack of dietary fibre or dehydration. However, sometimes the ingredients in the supplement may trigger constipation.

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Common Causes Of Constipation

• Eating foods low in fibre.

• Not drinking enough water (dehydration).

• Not getting enough exercise.

• Changes in your regular routine, such as traveling or eating or going to bed at different times.

• Consuming large amounts of dairy products such as milk and cheese.

• Stress.

• Resisting the urge to have a bowel movement (1).

Can Too Much Protein Cause Constipation?

For most people a diet high in protein should not cause any issues. However, high protein diets which severely restrict carbohydrates and dietary fibre can cause issues such as constipation (2). This makes it important for individuals following a high protein diet to ensure they are consuming enough fibre. 

The recommended intake of dietary fibre in the US and most European countries is between 30 and 35 grams per day for men and between 25 and 32 grams per day for women (3). With a high protein diet it is this lack of fibre rather than too much protein being consumed which causes the issue of constipation.

Can Whey Protein Powder Cause Constipation?

Whey protein shakes have high protein contents and contain all nine essential amino acids. Whey protein powders are produced using the liquid part of the milk which separates during the cheesemaking process. This liquid part of the milk is called whey, hence the term whey protein.  This whey is then further processed to form whey concentrate. With further processing whey isolate powder is formed. Whey protein isolate is a form of whey protein which has a higher protein content per gram of weight, with lower carbohydrate, fat and lactose. However, research has found both whey protein isolate and concentrate, have lactose levels which are low enough to not cause lactose intolerant individuals issues (4).

Despite this those with milk allergies or a lactose intolerance may suffer from constipation after consuming a whey protein supplement (5, 6). Any type of protein shake may cause issues in the first few days of consuming it, but if problems persist, it is best to switch to another brand or consult with a medical professional. If you believe, your issues are caused by lactose intolerance or an allergy to milk a non-dairy protein powder may be better for you.

If suffering from constipation whilst consuming a whey supplement, in most cases the protein supplement will not be to blame. The most likely causes are dehydration, a lack of dietary fibre or taking the protein shake with milk. Try increasing your water intake, adding fibre to your diet and taking your whey supplement with water rather than milk. If symptoms persist switch to another powder or consult with a medical professional.

Can Plant-Based Protein Powders Cause Constipation?

Some people choose to avoid animal based supplements such as whey protein for health or lifestyle reasons. Plant-based protein supplements can use one of or a blend of the following protein sources:

• Peas

• Hemp Protein

• Pumpkin Seeds

• Brown Rice

• Soy

• Chia

Most plant based powders are derived from legumes and seeds. Research has found the ‘protein package’ provided by plant based proteins gives the consumer several benefits including a high amount of dietary fibre which is absent or limited in animal based proteins (7). This extra fibre makes plant based protein supplements a possible solution to those who have suffered from adverse effects when consuming whey protein. Pea protein isolate can offer similar protein levels to most whey protein supplements and is also hypoallergenic (8).

Additionally, research has found pea protein isolate to be comparable to whey protein when it comes to promoting strength, performance, body composition, and muscular adaptations (9). Despite the extra fibre found in most plant based powders, to minimise the chances of suffering from constipation it should be ensured enough dietary fibre and water is consumed. The recommended total daily fluid intake for men is 3,000 ml and for women is 2,200 ml (10).

One possible cause of constipation with plant based powders is they are sometimes sweetened with non-calrodic artifical sweetners (NAS). These have been linked to intestinal troubles and glucose intolerance, so it is best to avoid them altogether when possible (14).

How Do I Prevent Constipation From Protein Shake Consumption?

The most likely causes of constipation are dehydration and a lack of fibre.

Drink Enough Water

Research has found fluid loss and fluid restriction increase constipation (11). This makes hydration vital in order to prevent constipation. Those who are taking protein shakes are often fitness enthusiasts or athletes who are consuming them to help with various types of training. This means they are likely to sweat more than an average individual. Therefore, it is vital athletes and fitness enthusiasts taking protein shakes make sure they are consuming their recommended fluid intake and also replace any fluids they lose through sweating during exercise.

With regards to a high protein diet having any impact on dehydration the evidence is minimal. A small study found a diet high in protein silently caused dehydration in endurance athletes (12). However, a larger study found the effect of increasing dietary protein on fluid status was minimal (13).


Research has found increased fiber intake benefits a number of gastrointestinal disorders including constipation (15).Fibre is the edible parts of carbohydrates or plants which are not easily digested. Fibre can be found in all plant foods including; fruits vegetables, nuts, legumes seeds and grains. A type of fibre called chitin can also be found in the shells of crustaceans. Some fibres are water soluble whilst others are insoluble. Soluble fibre slows the digestion process and helps the absorption of nutrients from food. Insoluble fibre draws water into and adds bulk to the stools, helping them pass through the intestines at a faster rate.

Types of Soluble Fibre

• Apples

• Lemon

• Orange

• Carrots

• Barley

• Oats

• Peas

• Beans

Types Of Insoluble Fibre

• Potatoes

• Nuts

• Beans

• Cauliflower

• Wheat Bran

• Whole-wheat Flour


Protein shakes are great dietary supplements for individuals wanting to increase their daily protein intake. The consumption of a protein shake should not cause constipation in individuals who do not have allergies. The most likely reason for constipation when consuming protein shakes is inadequate hydration or a lack of dietary fibre. However, the ingredients added to some protein shakes may cause constipation. 

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