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What Your Diet Is Really Doing to Your Poop, According to Science

We all know that what goes in, must come out. So, it’s a no-brainer that what you eat has a direct effect on your bowels. Switching up your diet or eating something new can impact how frequent and how often you have to go number two, and it’s important to talk about it.

“I definitely think it should be less of a taboo to talk about our poop. There are some changes that can occur with our stools which may be an indication of something more sinister going on,” Isa Robinson, a Registered Associate Nutritionist said. “Talking about these things means people may be more likely to visit their GP and have the necessary investigations carried out earlier.”

So, how can you prepare for changes in your bowel movements based on a new diet or healthy eating plan? We’ve compiled a few of the most popular diets right now (with the knowledge that fad diets and diet culture have a host of problems) and asked professionals to weigh in with their thoughts.


The Mediterranean diet was introduced in the 1960’s after scientists linked longer life spans in Mediterranean countries to their daily diet. They concluded that individuals living in countries like Greece and Italy consumed a diet primarily of vegetables, fruits, whole grains and very little red meat and dairy products. In other words, a diet high in soluble fibers.

“Soluble fiber is found in nuts, seeds, oats, peas, beans, and fruits, like apples and pears. Soluble fiber helps keep your poop soft, but still formed,” Samantha Cassetty, MS, RD, nutrition and wellness expert with a virtual counseling practice in New York City said. “This is what makes poop easier to pass.”


Saying goodbye to meat is a great way to keep your poop regular and healthy. Because the vegetarian diet is comprised mainly of vegetables and fruits, your consumption of fiber is much higher than it would be on a carnivorous diet.

“One of fiber’s many benefits is that it adds bulk to the stools, helping everything pass through. Fiber can provide a nice little push,” Robinson said.


Just like the vegetarian diet, going vegan will improve your bowel movements and the regularity of them. And with the vegan diet going one step further and cutting out dairy and eggs, your time in the bathroom will likely be easier and quicker.

However, Robinson does point out that eating a regular balanced diet is crucial, especially when consuming a diet that restricts many foods: “By ‘balanced meals,’ I’m usually talking about including three macronutrient proteins, carbohydrates, fat and some fruit or veggies too.”


The paleo diet, also known as the caveman diet, lets you consume as much meat as possible, but this is where you can get backed up…fast. Meat tends to take longer to digest but Robinson says consuming a balance of fruits and vegetables with this diet, should help with constipation.


The keto diet places a high emphasis on consuming mainly protein and fat but keeping your carb intake below 40 grams per day. But this is where you run into a little more trouble.

“Since the keto diet drastically eliminates carbohydrates, it’s very difficult to hit your fiber targets and therefore, may be hard to maintain regular bowel movements,” Cassetty said. Expect infrequent and liquid poops. “And since the keto diet eliminates so many plant foods that provide substances related to gut health, keto dieters often complain of constipation.”

Whatever diet you choose, nutritionists agree that it’s important to remember to consume a healthy balance of fiber-packed foods.

“Most Americans don’t hit the daily fiber targets of 25-38 grams per day. If you’re not regularly consuming this amount from a range of sources you might become constipated, which can be uncomfortable,” Cassetty said. “For people with IBS — either accompanied by diarrhea or constipation — diet can be a trigger. In this instance, understanding the foods that trigger your symptoms can be life changing.”

Read on to get real about diet trends and fads:

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