Do You Poop Less In A Calorie Deficit?

Irregular bowel movements may be related to inadequate calorie intake, especially a very low carbohydrate diet, according to experts.

pooping less in calorie deficit

Do you poop less in a calorie deficit?

One of the most common things I’ve noticed during my calorie deficit experiments was a change in my bowel movements (more specifically, I was pooping less).

On the other hand, the moment I change my diet again (increase calorie intake), and eat 3 square meals a day, my bowel movements go back to normal.


I went down the rabbit hole and scavenge through several PubMed and Google Scholar articles to learn more about pooping and calorie deficit.

Anyway, you will like this one.

Do you poop less when losing weight?

“Eating fewer calories leads to less food passing through your gut. And, peristaltic movements can slow down, which leads to less frequent pooping,” says David Parés, MD, Ph.D., from the Hospital de Can Ruti in Barcelona.

“The amount of food you eat has to transit through the intestinal tract,” explains Dr. Parés.

In our email conversation, I asked Dr. Parés about any correlation between weight loss and stool frequency.

“Okay, so with less food, the gut motility (and frequency) decreases. However, these changes are mainly due to acute caloric and food portion restriction, rather than a decrease in body weight,” says Dr. Parés.

Is pooping less related to weight loss?

It may seem logical that pooping less is related to weight loss, but that’s not the case, according to studies.

Beate Ott, MSc, an expert on gut permeability and gut microbiota composition from the Technical University of Munich, conducted a study on 20 women who underwent calorie deficit for 4 weeks.

The participants were instructed to consume 800 kcal per day.

Beate Ott explains that “this particular study aimed to investigate whether the caloric restriction is able to change gut permeability.”

“Apart from the significant weight loss (7 kg, on average), during the 4-week study, every person reported lower gut permeability and frequency in bowel movements,” says Beate Ott.

Do you poop more when gaining weight?

Eating more food means more waste in your digestive tract, which can result in more frequent bowel movements, says Beate Ott.

In her aforementioned study, Beate Ott explains that the same group of 20 women did a 2-week-long follow-up and consumed 1,700 kcal per day (normal food intake).

Surprisingly, after 2 weeks of follow-up, says Beate Ott, gut permeability and stool frequency increased significantly again.

This experiment suggests that you (indeed) do poop less when you eat fewer calories.

It also suggests that eating more can be related to frequent bowel movements, but it’s not necessarily related to weight gain.

Lower gut permeability and stool frequency (less pooping) were due to the lower food amount, not due to the weight loss or weight gain.

Why do I poop less on a diet?

“There are several reasons why people experience lower peristaltic motility during weight loss,” explains Beate Ott.

For instance:

  • reduced food amount;
  • lower water content;
  • less fiber-rich foods;
  • certain medications; and
  • stress.

Reducing food intake oftentimes goes hand in hand with lower carbohydrate intake (which are also high in fiber).

And, according to the British National Health Service (NHS), some antibiotics can negatively affect the digestive system.

Finally, the weight loss process itself can also contribute to stress and anxiety, which in some people can cause bloating, pain, and constipation, NHS states.

Can changing diet affect bowel movements?

A lot of things can affect how we poop, and how often.

Eating healthy and changing your diet, especially when eating more soluble fiber (often found in plant-based diets), may make your poop larger and softer.

On the contrary, eating foods that lack fiber may make stool harder.

So, yeah.

Changing your diet can affect your bowel movements.

New types of foods, different food compositions, or even new eating environments can play a role in the frequency of your bowel movements.

From my experience, I noticed that my bowel movements change in specific situations.

For instance:

  • traveling (especially long-haul flights that take 7 hours or longer);
  • sleeping in a new place (new environment, different time zone, etc.);
  • using a different bathroom (I try to avoid going for number 2 away from my home);
  • thinking about something (I often have to run to the bathroom immediately after an emotional event); and
  • stress.

What to do when eating healthy but not pooping?

Okay, what happens when my bowel movements seem odd, despite having my diet dialed in? These steps can help you poop more frequently.

Increase your physical activity

Apart from the low-calorie diet, one of the reasons for pooping less can be due to a lack of physical activity, according to Ruitong Gao, Ph.D. systematic review and meta-analysis.

Start by doing regular aerobic exercise, ideally in the lower-to-medium intensity. This can be walking, cycling, or slow jogging.

You can combine aerobic training, and weight lifting with a calorie deficit, as long as you focus on compound movements.

Watch how much food you eat

The amount of food you eat can be the most important predictor of how much you will poop. Notice your bowel movement habits with certain foods.

Use a food journal and write down your physical sensations to help you spot the changes. Add more potatoes and other starchy foods that have a high satiety value (which will keep you fuller for longer).

Watch what type of foods you eat

Below you can see a comprehensive video from Well+Good where they explain foods to eat to help your bowels move.

Add more fiber-rich foods to your diet (I’ve already explained that high-fiber foods can increase bowel movements in my other article).

At the same time, try to avoid processed foods, cakes, sweets, and other low-fiber meals. A diet that has a low amount of fiber can lead to constipation, bloating, and difficulty in relaxing.

One study compared a group of healthy men eating a low-fiber diet with a high-fiber diet.

Low fiberHigh fiber
Stool weight51g157g
Number of bowel movementsOnce in 33hOnce in 19h
Transit time48h19h
Source: (PMID: 632492)

Looking at the chart above you can see how a lack of fiber can affect bowel movement.

Stay hydrated

NOTE: For every gram of carbohydrates our body stores 3 grams of water. When you eliminate carbs from your diet, your body doesn’t hold into the water as it used to.

In other words, with a low volume of carbs, we often can lose water levels. Start your day by drinking 400-600 ml of water. (You can add some lemon or lime for extra flavor.)

Then sip 200-300 ml every 3-4 hours (or whenever you feel thirsty). Check and monitor your urine levels to notice any signs of dehydration.


Calorie restriction, changing the environment, changing diet, and stress can all alter the frequency of your bowel movement.

The best practice you can do is to make sure you’re drinking enough water, eating fiber-rich foods, staying physically active, getting plenty of rest, and being mindful when traveling.

Michal Sieroslawski

Michal is a personal trainer and writer at Millennial Hawk. He holds a MSc in Sports and Exercise Science from the University of Central Lancashire. He is an exercise physiologist who enjoys learning about the latest trends in exercise and sports nutrition. Besides his passion for health and fitness, he loves cycling, exploring new hiking trails, and coaching youth soccer teams on weekends.

2 thoughts on “Do You Poop Less In A Calorie Deficit?

    1. There is one study (at least that I’m aware of) that documents “a positive association between the severity of constipation and sarcopenia in elderly adults”. Hope that helps

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