What Will Happen If We Don't Include Fiber in Our Food?

December 18, 2025 •

3 min read

Over 90% of Americans are not consuming enough fiber daily, a significant health concern. But what will happen if we don't include fiber in our food has profound implications for digestive health, disease prevention, and overall well-being.

Quick Summary

A lack of dietary fiber can result in serious health issues, including chronic constipation, blood sugar fluctuations, and weight gain. Over time, it increases the risk of heart disease, type 2 diabetes, and specific cancers.

Key Points

Constipation and Hemorrhoids: A diet lacking fiber leads to hard, dry stools and can cause chronic constipation, straining, and the development of hemorrhoids.
Increased Disease Risk: Low fiber intake is linked to a higher risk of heart disease, type 2 diabetes, colorectal cancer, and diverticulitis.
Gut Microbiome Imbalance: Fiber feeds beneficial gut bacteria; without it, the microbiome becomes imbalanced (dysbiosis), which can lead to inflammation and weakened immunity.
Weight Management Issues: High-fiber foods promote satiety, helping to manage weight. A low-fiber diet often leads to increased hunger and overeating.
Energy Fluctuations: Without fiber to regulate sugar absorption, you may experience energy spikes and crashes, leading to fatigue and mood swings.
Poor Skin Health: The link between gut and skin health means a low-fiber diet can lead to inflammation that manifests as skin problems like acne and dryness.

A well-balanced diet is a cornerstone of good health, and dietary fiber is one of its most essential yet overlooked components. Far from just a digestive aid, fiber supports numerous bodily functions, and its absence can cause widespread issues throughout the body. Understanding the cascade of problems that result from a low-fiber diet is crucial for taking control of your long-term health.

The Immediate Digestive Consequences

Without sufficient fiber, the digestive system struggles to function smoothly. Fiber adds bulk to stool, which helps it pass through the colon efficiently. The two main types of fiber—soluble and insoluble—play distinct but equally important roles. Without them, several unpleasant and uncomfortable digestive issues can arise almost immediately.

Constipation and Associated Problems

The most common and immediate effect of a low-fiber diet is constipation. Insufficient fiber leads to hard, dry stool that is difficult to pass, often causing straining and increasing the risk of hemorrhoids and anal fissures.

Bloating and Gas

While increasing fiber can cause temporary gas, a chronic lack of fiber can also lead to bloating and gas due to a sluggish digestive system and waste buildup.

Long-Term Health Risks of Fiber Deficiency

The long-term consequences of a low-fiber diet are significant and can develop over time.

Increased Risk of Chronic Diseases

Low fiber intake is linked to a higher risk of several chronic diseases:

Heart Disease: Soluble fiber helps lower LDL cholesterol, reducing the risk of cardiovascular issues.
Type 2 Diabetes: Fiber helps regulate blood sugar, and a low-fiber diet increases the risk of insulin resistance and type 2 diabetes.
Colorectal Cancer: Fiber speeds up waste transit, limiting exposure to potential carcinogens in the colon.
Diverticular Disease: Straining from constipation can lead to the formation of pouches (diverticula) in the colon, which can become inflamed (diverticulitis).

Disruption of the Gut Microbiome

Fiber feeds beneficial gut bacteria, essential for a healthy microbiome. A lack of fiber disrupts this balance (dysbiosis), potentially leading to inflammation, weakened immunity, and mood changes.

Low Fiber and Lifestyle Issues

A lack of fiber can also impact daily life and overall well-being.

Weight Gain

Fiber promotes satiety, helping control appetite and weight. A low-fiber diet can lead to increased hunger and overeating.

Fatigue and Energy Crashes

Fiber helps stabilize blood sugar and energy levels. Without it, energy spikes and crashes can cause fatigue and lack of focus.

Soluble vs. Insoluble Fiber Comparison


Feature	Soluble Fiber	Insoluble Fiber
Action in the Body	Dissolves in water to form a gel-like substance.	Does not dissolve; passes through mostly intact.
Main Benefits	Lowers cholesterol, regulates blood sugar, promotes satiety, and feeds good gut bacteria.	Adds bulk to stool, promotes regularity, and prevents constipation.
Food Sources	Oats, peas, beans, apples, carrots, barley, citrus fruits, psyllium.	Whole-wheat flour, wheat bran, nuts, green beans, cauliflower, potato skins.
Effect on Stool	Softens stool by absorbing water.	Increases stool bulk and weight.

How to Increase Your Fiber Intake

To improve your fiber intake, gradually add more fiber-rich foods to your diet and drink plenty of water. Consider these tips:

Choose whole grains over refined grains.
Increase your vegetable intake at meals.
Snack on fruits, nuts, and seeds.
Add legumes to your meals.
Ensure adequate hydration.

Conclusion

Consuming enough dietary fiber is crucial for preventing a range of health problems, from digestive discomfort to serious chronic diseases. Fiber plays a vital role in maintaining a healthy body. By incorporating more fiber-rich foods into your diet, you can significantly improve your digestive health, manage your weight, boost energy levels, and reduce your risk of chronic illness. Making conscious choices to increase fiber intake is a fundamental step towards a healthier future. For more detailed information on dietary fiber, refer to resources like the Mayo Clinic.

Frequently Asked Questions

The primary function of fiber is to keep the digestive system healthy and regular. It adds bulk to stool, which helps move waste through the intestines and prevents constipation.

Yes, a chronic lack of fiber can lead to bloating and gas. A slow, congested digestive system can cause an increase in gas and abdominal discomfort.

Yes, fiber deficiency can cause blood sugar levels to fluctuate dramatically. Soluble fiber slows sugar absorption, so without it, rapid spikes and subsequent crashes can occur.

Soluble fiber dissolves in water to form a gel, which helps lower cholesterol and blood sugar. Insoluble fiber does not dissolve and adds bulk to stool to promote regularity.

A low-fiber diet can contribute to weight gain because fiber promotes a feeling of fullness. Without enough fiber, people may feel hungrier more often, leading to overeating.

A low-fiber diet is linked to a higher risk of heart disease, type 2 diabetes, colorectal cancer, and diverticular disease.

Yes, insufficient fiber can lead to fatigue and low energy. The blood sugar fluctuations resulting from a low-fiber diet cause energy crashes, leaving you feeling drained throughout the day.