Too much fiber can cause symptoms such as bloating, gas, and constipation. In rare cases, it can cause intestinal blockage. Fluids, exercise, and dietary changes may help the body manage more fiber.

Dietary guidelines suggest a person should eat around 14 grams (g) of fiber for every 1,000 calories they consume. Eating more than this may lead to side effects, including gastrointestinal discomfort.

Eating too much fiber may be more likely in a person following a vegan, whole food, or raw diet.

This article explains what fiber is, how much to eat, how to tell when you have eaten too much, treatments, and good sources of fiber to introduce into a healthful diet.

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Fiber is the indigestible part of plants and carbohydrates. Foods like lentils, vegetables, and cereals are high in fiber.

There are two types of dietary fiber:

  • Insoluble fiber: This type does not break down as it passes through the digestive system. It adds bulk to bowel movements and helps to move food along. Sources include plant skins and certain green vegetables.
  • Soluble fiber: This type forms a gel when it mixes with water and bacteria in the digestive system breaks it down. It helps keep stools soft and slows the digestive process. Sources include certain grains, seeds, and legumes.

A diet rich in fiber is essential for keeping the digestive system healthy. Research relates it to lower blood pressure and a reduced risk of heart problems, diabetes, and obesity.

However, according to a 2022 article, many people across the world do not eat enough fiber.

In general, eating too much fiber is a less common problem than eating too little.

According to the United States Department of Agriculture (USDA) Dietary Guidelines for Americans 2020–2025, over 90% of females and 97% of males do not eat enough fiber.

The optimal amount of fiber varies based on an individual’s gender, age, and pregnancy status.

The USDA recommends that adults consume around 14 g of fiber for every 1,000 calories of food they eat. For someone eating around 2,000 calories a day, this will mean eating about 28 g of fiber.

Eating more than this daily recommendation can cause uncomfortable side effects, especially if a person is not drinking enough water. Boosting fiber intake suddenly may also lead to side effects.

The most common symptoms of eating too much fiber are:

Too much fiber may also cause nutrient deficiencies, as it can interfere with the body’s ability to absorb essential nutrients. This unwanted result is because the fiber binds with minerals, including calcium, zinc, and iron.

Fiber makes bowel movements bigger and bulkier. It also promotes fermentation and gas formation. This is why excessive fiber intake frequently affects the digestive system.

However, for some people, particularly those with irritable bowel syndrome (IBS), low fiber levels can cause the digestive symptoms above, and increasing fiber levels might be beneficial.

If a healthcare professional confirms that a person’s symptoms are due to excessive amounts of fiber, they may suggest the following steps to manage symptoms:

  • reducing fiber consumption
  • increasing fluid intake
  • getting more exercise
  • avoiding food that increases bloating, such as chewing gum

An older study from 2012 tested the effects of changing the fiber intake of 63 people experiencing constipation, bloating, and stomach pain.

In this study, individuals who reduced their fiber intake had more frequent bowel movements, less bloating, and less abdominal pain.

A low fiber diet

If a person has severe symptoms, a doctor may recommend a low fiber diet, which means eating low fiber foods until their symptoms ease. Doctors may prescribe this diet for individuals with serious digestive conditions or after certain procedures.

A person might include the following foods in a low fiber diet:

  • white bread, rice, or pasta
  • corn or rice breakfast cereals
  • potatoes without skins
  • tomato products without skins
  • well-cooked vegetables without skins
  • smooth fruit juices
  • fresh meat without excess fat
  • fish
  • dairy, including milk, cheese, and smooth yogurts
  • eggs

People should speak with their doctor before trying a low fiber diet, as it is not suitable for everyone.

Both soluble and insoluble fiber are necessary for a healthful diet. Individuals can strive to reach the recommended daily level of dietary fiber by eating a diet rich in:

According to the British Heart Foundation, it is better to consume naturally occurring fiber than to get fiber from supplements.

According to a 2020 narrative review, dietary fiber may offer the following benefits:

When someone has eaten too much fiber, the discomfort will pass over time as the body eliminates the fibrous foods.

People may relieve their discomfort by decreasing their fiber intake to the daily recommendation, increasing the amount of water they drink, and exercising more.

They can also speak with a healthcare professional for treatment to relieve their symptoms.

Below are some common questions about excess fiber intake.

Why would someone have constipation even though they eat a lot of fiber?

A person can experience constipation if they eat too much or too little fiber. People should aim to eat around 14 g of fiber for every 1,000 calories of food.

If someone thinks their fiber levels are causing constipation, they should speak with a healthcare professional for further help.

How can someone fix constipation from too much fiber?

A person should speak with a healthcare professional before adjusting their fiber levels to ensure that excess fiber is definitely the cause of their constipation. A doctor may suggest reducing their fiber intake or increasing their fluids and exercise.

Fiber is an essential part of a healthy diet. However, excessive amounts of fiber can cause symptoms such as constipation, discomfort, and nausea.

Healthcare professionals may recommend increasing fluid intake or exercising more to relieve these symptoms.

Achieving the recommended daily fiber targets is worth the effort because the health dangers of not eating enough fiber outweigh the discomfort of eating too much.