What causes a fiber deficiency? Understanding common dietary and lifestyle factors

December 3, 2025 •

4 min read

According to the National Health and Nutrition Examination Survey, a vast majority of Americans do not consume the recommended daily intake of fiber, and understanding what causes a fiber deficiency is the first step toward improving health. The reasons behind this deficiency are often rooted in modern eating habits and a heavy reliance on processed foods that strip away crucial nutrients.

Quick Summary

Several factors, including diets high in refined grains and processed foods, low consumption of fruits and vegetables, and certain medical conditions, contribute to insufficient dietary fiber intake. Awareness gaps and restrictive diet trends are also significant causes of low fiber levels. This comprehensive guide details the common culprits behind inadequate fiber and provides strategies for a healthier diet.

Key Points

Processed Foods are a Top Cause: Modern diets high in refined grains and processed items lack the bran, germ, and pulp where most fiber is found.
Inadequate Whole Food Intake: Low consumption of whole grains, fruits, vegetables, legumes, and nuts is a primary driver of fiber deficiency.
Restrictive Diets Limit Sources: Popular diets like low-carb or keto often exclude key fiber-rich foods, increasing the risk of a deficiency.
Lack of Awareness is a Factor: Many people are unaware of their daily fiber needs or are confused by misleading food labels, thinking they consume enough.
Medical Conditions Require Low Fiber: Some conditions or surgeries necessitate a low-fiber diet, but this should be guided by a doctor to manage symptoms or healing.
Gradual Changes are Best: To increase fiber, start slowly and drink plenty of water to allow your digestive system to adapt and prevent discomfort.
Whole Foods are Preferable to Supplements: Getting fiber from a variety of whole foods provides a broader range of nutrients than supplements alone.

A Diet High in Processed and Refined Foods

One of the most significant factors contributing to a fiber deficiency is a diet dominated by highly processed and refined foods. Modern diets often prioritize convenience and shelf life over nutritional value, a process that removes the most fiber-rich parts of whole foods.

The Impact of Grain Refining

For example, the process of refining wheat flour to make white bread removes the bran and germ, which contain most of the grain's fiber. Similarly, juicing fruits and vegetables removes the pulp and skin, where much of the fiber resides, leaving behind a drink with minimal fiber content. This overconsumption of fiber-poor products means many meals offer little to no dietary bulk, a key component for digestive health.

Low Intake of Whole Foods

Dietary fiber is found exclusively in plant-based foods, and a lack of these items is a direct cause of deficiency. The average diet often lacks sufficient amounts of whole grains, legumes, fruits, vegetables, and seeds.

Common deficiencies include:

Fruits and vegetables: Many individuals simply do not meet the recommended daily servings of fresh produce, which are packed with fiber. Eating fruits with their skin on, like apples and pears, can boost fiber intake.
Legumes: Foods like lentils, beans, and chickpeas are excellent sources of both soluble and insoluble fiber but are often overlooked. For instance, a low-carb diet that skips beans can cut out 7 to 9 grams of fiber per cup.
Whole grains: Replacing refined items like white rice and pasta with whole-grain alternatives such as brown rice, quinoa, and whole-wheat pasta is a crucial step towards increasing fiber.
Nuts and seeds: These are easy-to-add sources of fiber, with options like chia seeds, flaxseeds, and almonds offering a significant boost.

The Influence of Restrictive and 'Fad' Diets

Popular restrictive diets, such as low-carb or keto diets, often involve limiting or excluding major sources of dietary fiber. While intended for specific health goals, these eating patterns can inadvertently lead to a severe fiber deficiency. A diet that cuts out grains, legumes, and certain fruits for extended periods of time necessitates careful planning to ensure fiber is obtained from other approved sources.

Lack of Awareness and Misperception

Many people are not aware of the recommended daily fiber intake, or they mistakenly believe they are consuming enough. Food labeling can also contribute to this confusion. For example, some products labeled as "multigrain" or containing "whole-grain ingredients" may not actually be a good source of fiber. Without checking the Nutrition Facts panel, consumers can be misled into thinking they are making healthier choices.

Comparison of Processed vs. Whole Foods


Food Type	Example	Fiber Content	Impact on Diet
Processed	White Bread	Low (bran and germ removed)	Contributes to low fiber intake; can cause rapid blood sugar fluctuations
Whole Food	Whole-Wheat Bread	High (intact bran and germ)	Supports healthy digestion and stable blood sugar
Processed	Fruit Juice	Low (pulp removed)	High in sugar; lacks the digestive benefits of whole fruit
Whole Food	Whole Apple	High (skin and pulp intact)	Offers soluble and insoluble fiber; aids satiety
Processed	Sugar-Sweetened Cereal	Low (refined grains)	Contributes to fatigue and poor energy levels due to sugar spikes
Whole Food	Oatmeal	High (whole grain)	Provides sustained energy; excellent source of soluble fiber

Specific Medical and Surgical Reasons

In some cases, a low-fiber diet is medically prescribed to rest the bowels due to certain health conditions or after surgery. Reasons for this include:

Inflammatory Bowel Disease (IBD) flare-ups: Conditions like Crohn's disease or ulcerative colitis sometimes require a temporary low-fiber diet to manage symptoms.
Bowel surgery: After certain procedures, a low-fiber intake is necessary to allow the digestive system to heal.
Bowel obstruction: In cases of blockage due to a tumor or scar tissue, a low-fiber diet may be recommended to reduce the amount of undigested material moving through the intestines.
Radiation therapy: Treatments targeting the pelvic and lower bowel areas can irritate the digestive system, making a low-fiber diet necessary.

Conclusion: The Path to a Fiber-Rich Diet

Understanding what causes a fiber deficiency is crucial for improving overall health, but the good news is that the solution is often straightforward. By shifting away from diets heavy in processed and refined foods and towards those rich in whole, plant-based sources, you can significantly increase your fiber intake. Gradual dietary changes, such as swapping white bread for whole-wheat or adding legumes to soups and salads, can effectively increase fiber and promote better digestive, metabolic, and cardiovascular health. A focus on whole grains, fruits, vegetables, nuts, and seeds provides a variety of fiber types and essential nutrients that supplements alone cannot replicate.

For more information on the science of nutrition and the impact of fiber, see the excellent resources available from institutions like the American Cancer Society, found here: https://www.cancer.org/cancer/survivorship/coping/nutrition/high-fiber-foods.html.

Taking Control of Your Fiber Intake

Addressing a fiber deficiency involves conscious food choices, education, and mindful eating. Remember to increase your intake gradually and drink plenty of water to help your body adapt and avoid discomfort. A diverse diet filled with whole, minimally processed plant foods is your best defense against inadequate fiber and the health issues that can follow.

Simple Strategies for Boosting Fiber

Incorporating more fiber into your diet doesn't have to be complicated. Start with small, manageable changes that fit into your daily routine.

Begin your day with a high-fiber breakfast, such as oatmeal with berries or a whole-grain cereal.
Add beans or lentils to soups, stews, and salads.
Snack on nuts, seeds, or fresh vegetables with hummus.
Swap refined grains for whole-grain alternatives like quinoa, brown rice, or whole-wheat pasta.
Eat fruits and vegetables with the skins on whenever possible.
Choose frozen berries for smoothies to get fiber at a lower cost.

By taking these steps, you can avoid the risks associated with a low-fiber diet and enjoy the numerous benefits of higher fiber consumption.

Frequently Asked Questions

Processed foods cause fiber deficiency because their production involves refining and removing the fiber-rich parts of whole grains, fruits, and vegetables. For instance, white flour lacks the bran and germ found in whole-wheat flour, which significantly reduces its fiber content.

The recommended daily fiber intake varies slightly by age and gender, but is generally around 25 grams for women and 38 grams for men. A large percentage of the population falls short of these recommendations.

Yes, low-carb diets can lead to fiber deficiency. Many high-fiber foods, such as grains, legumes, and some fruits, are limited or excluded from low-carb eating plans, making it challenging to meet fiber goals.

Yes, juicing removes most of the fiber from fruits and vegetables. The pulp and skin, which are the main sources of fiber, are discarded in the juicing process. Eating the whole fruit is a much better way to get fiber.

Globally, fiber intake is consistently low due to shifting dietary patterns that favor processed foods over nutrient-rich whole foods, as well as a general lack of awareness about dietary needs.

If on a restrictive diet, you can increase fiber by focusing on the allowed fiber-rich options. This may include nuts, seeds, and certain vegetables and fruits, but it is important to consult a healthcare professional to ensure you are meeting nutritional needs.

Yes, certain medical treatments or conditions can necessitate a temporary low-fiber diet, which can lead to a deficiency. Examples include inflammatory bowel disease flare-ups, bowel surgery, or radiation therapy to the digestive tract.

It is generally better to get fiber from whole foods rather than supplements. Whole foods provide a wider range of beneficial nutrients, including different types of fiber, vitamins, and minerals, that supplements cannot replicate.