INTRODUCTION

One common complaint from some people that have tried a low-carb ketogenic diet but then gave up on it is that they had issues with constipation and abdominal bloating. The good news is that there are some easy ways to avoid developing constipation on a ketogenic or low-carb diet.

WHAT CAUSES CONSTIPATION ON A KETOGENIC DIET?

The one issue with constipation is slower transit time thru the small and large intestines. With that slower transit time of stool through the large intestine, more water can be absorbed out of it.

As a result of the water being pulled from the stool and through the wall of the large intestine, the stool becomes firmer and harder, sometimes resulting in constipation. This constipation can result in having to strain to have a bowel movement or causing that bloated stomach feeling that some of us have experienced.

There can be a number of reasons for the change in the transit time thru the intestine that results in constipation

LACK OF FIBER AND CHANGE IN YOUR GUT BIOME CAN CAUSE CONSTIPATION

Constipation can occur on a ketogenic diet because of a change in the gut bacteria (your gut microbiome) and changes in food choices when you’re starting a ketogenic low carb diet

We do see a change in the gut biome or the gut bacteria on a ketogenic diet and that change in your gut microbiome can lead to bowel issues such as constipation or abdominal bloating.

This change in the gut bacteria on a ketogenic diet usually is due to a lack of fiber on the diet. Some people completely cut out ALL vegetables and fruit when they first start on a low-carb ketogenic diet.

This important dietary fiber is the necessary and healthy prebiotic foods that your gut microbiome need in order to survive and function properly, so suddenly eliminating dietary fiber can lead to constipation.

OTHER MEDICAL CONDITIONS OR MEDICATIONS THAT CAN CAUSE CONSTIPATION

Medical conditions such as diabetes or hypothyroidism can cause constipation so its important to follow up with your doctor if your constipation has been an on-going issue or does not respond with changes in your diet.

Several different classes of medications can cause constipation as well. Narcotic or opioid pain medications like morphine or hydrocodone are well-known to cause constipation in patients that are prescribed them.

Certain classes of blood pressure medications such as alpha-blockers (Catapress, doxazosin), beta-blockers (metoprolol or  propranolol) or calcium-channel blockers like amlodipine or nifedipine can also cause constipation.

Over-the-counter medications like non-steroidal anti-inflammatories (ibuprofen or naproxen) or antihistamines such as Benadryl can sometimes result in constipation as well. 

Even supplements like iron can end up causing constipation in a large number of people that are taking them.

*** If you suspect that your medication is causing your constipation, talk to your prescribing doctor before you  stop or make any medication changes***

DEHYDRATION CAN CAUSE CONSTIPATION ON A KETOGENIC DIET

When you start on a low-carb ketogenic diet, you might already know that some of the initial weight loss is due to water weight (diuresis) as the body’s glucose and glycogen stores decrease, you will urinate out the water that was stored with the glycogen and glucose. For each gram of glucose/glycogen, the body stores about 4 grams of water. When those glycogen stores drop, the water has to go somewhere and that means less water in your body to be pulled into the large intestine to keep the stool soft.

Remember to stay well-hydrated, especially when starting on the ketogenic diet, and the extra water intake should help prevent or minimize any constipation.

PREVENTING CONSTIPATION WITH SOLUBLE AND INSOLUBLE FIBER ON A KETOGENIC DIET

There are two types of dietary fiber; soluble fiber,  which is absorbed into the water and kind of pulls water back into the gut, and insoluble fiber, which actually acts more as a bulking agent.

Both types of dietary fiber are important for proper gut health and function. So sure you’re getting at least a good mix of soluble fiber, vegetables, and fruit in your diet that don’t increase your glucose and insulin levels and knock you out of ketosis.

There are a variety of high fiber prebiotic foods that you can eat on a ketogenic diet that have that soluble fiber in there.

Psyllium husks have a good combination of mostly soluble fiber with some insoluble fiber. If you have ever taken Metamucil, then you’ve taken psyllium husks 

Typically just a scoop of psyllium husks in a glass of water in the morning should give you enough soluble fiber to help prevent developing constipation on a ketogenic diet

Other high fiber foods  (those healthy prebiotic foods that we’ve talked about before) that you can eat on a low-carb ketogenic diet include:

• Asparagus
• Berries (blackberries, raspberries and strawberries)
• Broccoli 
• Cabbage
• Cauliflower
• Garlic
• Green bananas 
• Leeks and green onions
• Mushrooms
• Peppers (bell peppers)
• Salad greens
• Sauerkraut
• Seeds such as flax seeds, hemp seeds and chia seeds

Conclusion

Avoiding constipation on a low-carb, ketogenic diet can be as simple as making sure you get high-quality soluble fiber in your diet and remember to stay well-hydrated the first week of the diet.

Be sure to see your doctor if your constipation doesn’t improve to review your medications and determine if there is another reason for your constipation