This Common Diet Could Be Making It Harder for You to Poop, New Study Says

When researchers take a close look at how different eating patterns affect our overall health, there are certain diets that crop up in studies over and over again. Those old standards include the likes of the Mediterranean diet—often gauged by the Alternate Mediterranean diet (aMED) score—plant-based or vegetarian diets, an anti-inflammatory diet and others. Many researchers also examine the Western diet, a diet rich in processed food, red meat, salt and high-fat dairy.

The Western diet is also low in fresh fruits, veggies and whole grains—the opposite of something like the Mediterranean diet. While few experts recommend the Western diet as a healthy choice, it’s a common eating pattern for many people around the world, especially in the U.S. And though a Western diet can be convenient, it also comes with drawbacks.

Constipation is a particularly common complaint—affecting about 16% of American adults—and it can include hard stools, straining and that frustrating sensation of incomplete emptying. To better understand how different eating patterns affect digestive health, researchers analyzed data from nearly 96,000 people who were followed for up to 30 years. They examined how five dietary patterns—Mediterranean, plant-based, low-carbohydrate, Western and inflammatory eating patterns—influenced chronic constipation risk. Their findings, published in Gastroenterology, revealed that while some diets protect against constipation, low-carb diets may actually increase your risk.

How Was This Study Conducted? 

This study analyzed data from three well-established research projects: the Nurses’ Health Study, Nurses’ Health Study II, and the Health Professionals Follow-Up Study. Together, these included 27,774 older women, 55,906 middle-aged women and 12,237 older men.

Participants completed detailed food questionnaires every four years, allowing researchers to track eating habits over 25 to 30 years. Researchers calculated scores for five dietary patterns and gathered information about health behaviors, medical conditions and constipation symptoms—defined as being bothered by constipation for at least 12 weeks in the past year.

After following participants for two to four years and documenting 7,519 new constipation cases, researchers analyzed whether different dietary patterns were associated with constipation risk while accounting for factors like age, physical activity, smoking, medications and chronic diseases.

What Did the Study Find? 

The study revealed clear connections between dietary patterns and constipation risk. People who followed Mediterranean and plant-based diets most closely had 16% and 20% lower chances of developing constipation, respectively. These protective effects held up even after accounting for fiber intake, suggesting benefits beyond fiber alone.

Conversely, those with highest adherence to Western diets or inflammatory eating patterns faced 22% and 24% increased constipation risks, respectively. The researchers also assessed low-carb diets, but didn’t find a statistically significant relationship between low-carb diets and constipation.

The study had limitations worth noting. Since participants were mostly older, white health care professionals, findings may not apply to younger or more diverse populations. As an observational study, it shows associations but can’t prove specific diets directly cause or prevent constipation.

How Does This Apply to Real Life? 

These findings offer practical guidance for digestive health. If you’re eating a Western or otherwise inflammatory diet, try to make adjustments that gradually add more fresh fruits, veggies and whole grains to your routine. Those key food groups can help you eat enough fiber, which can also help lower your constipation risk. According to the Dietary Guidelines for Americans, adults should get between 25 and 34 grams of fiber per day. Staying hydrated can also help.

In this study, the standout performers were Mediterranean and plant-based diets. Both emphasize vegetables—especially leafy greens, cruciferous vegetables like broccoli, and tomatoes—along with nuts, legumes and healthy fats like olive oil. These foods provide more than fiber; they contain beneficial compounds that support gut bacteria and reduce inflammation. Considering adding meals like our Sweet Potato-Black Bean Stuffed Peppers and Marry Me White Bean Soup to your rotation for more plant protein and delicious flavor.

If you’re dealing with constipation, eating more plant foods may help. Load up on vegetables at every meal, snack on nuts, use olive oil for cooking and include beans or lentils regularly. You might also want to limit foods typical of Western diets, like processed meats and refined grains, which this study linked to increased constipation risk.

Our Expert Take

A new study in Gastroenterology suggests that the overall pattern of your diet matters for constipation risk. While Mediterranean and plant-based diets appear protective, Western and inflammatory eating patterns may increase your chances of developing chronic constipation. These associations held true even after accounting for fiber intake, suggesting that the benefits of healthful eating patterns extend beyond any single nutrient. If you’re struggling with constipation, consider talking with a registered dietitian who can help you adjust your eating pattern while ensuring you meet all your nutritional needs.