Chronic diarrhea more common in the obese

Chronic diarrhea is a common condition affecting nearly 20 million Americans every year. Many factors may contribute to the condition including:

  • Obesity
  • High daily carbohydrate intake
  • Being female
  • Feeling depressed

A lot of mystery surrounds the causes of diarrhea. As a result, people often have problems addressing it. One factor strongly associated with chronic diarrhea is obesity. However, there’s a lot going on there.

First of all, many behaviors that obese people regularly do promote diarrhea. But does being obese on its own contribute to chronic diarrhea? A study published last week indicates this is the case.

Chronic diarrhea

Chronic diarrhea and obesity

To untangle the relationship between obesity and chronic diarrhea, researchers looked at data from NHANES 2009-2010. Consequently, they analyzed the data and teased out the effects of other variables to see how strongly obesity associates with chronic diarrhea.

They found that obesity on its own increases the risk for chronic diarrhea by 60%. This is independently from other factors such as:

  • Gender, age, race, income, & education
  • Type 2 diabetes status
  • Exercise
  • Laxative use
  • Alcohol use
  • Milk intake
  • Carbohydrate, fat, protein, sugar, and fiber intake

This data is interesting, but for the things it doesn’t look at. People believe most of the above factors cause diarrhea. As a result, these are the factors people address. Above all, people often alter their diet.

Most try to increase fiber, decrease sugar, or tinker with their macronutrient profile. Think Keto, Carnivore, or low carb. Using the same dataset, previous research showed high carbohydrate intake increases chronic diarrhea risk by 56%.

The problem with those diets is that most of them, for most people, lead to weight loss. And since obesity correlates with chronic diarrhea, you don’t know if it’s the weight loss per se or the change in diet.

Other factors related to obesity

As a general principle, a combination of high calorie intake and low calorie usage leads to obesity. As a result, we store the extra as fat. Certainly there are other genetic and lifestyle factors at play, but they typically impact these factors.

For example, meal frequency and timing are both associated with obesity. Obese people tend to eat more frequently and consume dinner as their largest meal. Furthermore, four factors helped prevent obesity:

  • Eating less than 3 meals per day
  • Not skipping breakfast
  • Making breakfast or lunch the biggest meal
  • Maintaining a longer overnight fast

Another factor associated with obesity not controlled for in this study is nighttime eating. Eating dinner right before bed and snacking after dinner increase obesity risk. These behaviors double the risk for men and triple it in women.

A main factor driving the association between obesity and chronic diarrhea is chronic inflammation. On one hand, fat cells secrete inflammatory cytokines so having more fat leads to more inflammation.

But I think a bigger driver is increased inflammation in the gut. And these factors not controlled for in the study increase gut inflammation. The gut is like every other organ or tissue in the body: it needs recovery time.

This is where circadian rhythms come in to play. Circadian rhythms schedule use and repair. In order for any tissue to be resilient and function properly, you can’t use it too much or give it inadequate recovery time.

Eating exposes the gut to stress, and adequate recovery time is required to maintain resilience in the gut. Eating too much, too frequently, and at improper times decreases resilience in the gut. When you do all of these things all of the time, resilience is lost. This predisposes to disorders of the gut, including chronic diarrhea.


Obesity independently increases the risk for chronic diarrhea by 60%. Some of the risk likely lies in the increased inflammation from having more fat tissue. However, other behaviors explain the risk as well.

But you don’t have to be obese to experience chronic diarrhea. Behaviors that are more common in obese people may be the primary drivers of the increased risk. This includes eating too many meals, eating late at night, and eating most of your calories for dinner.

Therefore, changing these behaviors may give relief to people suffering from chronic diarrhea. This includes all people with these behaviors, not just the obese.

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