Are You Deficient in Fiber? Here Are 7 Symptoms You May Experience

Medically Reviewed by Felicia Newell, RD

December 1, 2023

Fiber is an essential nutrient that is vital in maintaining overall health. It aids digestion, helps control blood sugar levels, and even contributes to weight loss. Yet many of us don’t get enough of it.

Being deficient in fiber comes with noticeable symptoms—seven of which I outline in this article. Recognizing these signs—and thus increasing your fiber intake—can be the difference between having more energy, less inflammation, effortless weight loss, and more.

What Is Fiber—and How Much Do I Need?

Fiber, also known as dietary fiber or roughage, is a carbohydrate that our bodies cannot digest. Whereas other carbs (like sugars and starches) are absorbed into the bloodstream, fiber isn’t. Instead, it passes relatively intact through your stomach, small intestine, and colon out of your body. 

There are two types of fiber—soluble, which dissolves in water, and insoluble, which doesn't dissolve. Both types are pivotal in supporting a healthy digestive system, controlling blood sugar levels, maintaining a healthy weight, and reducing the risk of chronic diseases (1).

So, how much fiber should you be getting each day?

Here’s what the USDA recommends (2):

Grams of Fiber Per Day
Children (Aged 1-18 years old)
14-31 grams per day
Women (Under 50 years old)
25-28 grams per day
Men (Under 50 years old)
31-34 grams per day
Women (51 years and older)
22 grams per day
Men (51 years and older)
28 grams per day

These fiber intakes range from 14 to 34 grams, depending on gender and age. Yet Americans only get around 10-15 grams of fiber daily (3). This is a far cry from what the body needs, and we’re beginning to see the aftermath of what a fiber deficiency looks (and feels) like. In the next section, you’ll learn seven ways the body lets you know you’re deficient in fiber.

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7 Signs of Low Fiber Intake

Roughly 95% of Americans don’t consume enough fiber (4). Underconsumption of this key nutrient can lead to some unsavory health outcomes and surprising symptoms. The best way to know if you aren’t consuming enough fiber is by paying attention to your diet. But looking out for these signs of low fiber intake can also help.

1. Irregular Bowel Movements or Constipation

One telltale sign of low fiber intake is irregular bowel movements or constipation (5). Fiber adds bulk to your stool, aiding its movement through your digestive system. When you aren't getting enough fiber in your diet, your stool can become hard and difficult to pass, leading to constipation

If you find yourself frequently straining or experiencing discomfort during bowel movements, or if your bowel movements are less frequent than usual, these could be signs that you need to increase your fiber intake. Remember, it's crucial to maintain hydration when increasing fiber to prevent further digestive discomfort.

However, be aware that these signs can also be associated with other medical conditions, so it's always wise to consult a healthcare professional if you experience persistent digestive issues.

2. Weight Gain

Another sign that you may lack fiber in your diet is unexplained weight gain or difficulty losing weight. Fiber-rich foods tend to be more filling, so they can help prevent overeating and snack cravings. 

If you aren’t consuming enough fiber, you may find yourself eating larger portions to feel satiated, which can lead to weight gain. Not only that, but fiber helps maintain blood sugar levels, too. This prevents sudden spikes and crashes that can trigger hunger pangs. So if you’ve recently experienced a sudden change in your weight (without any major shifts in your lifestyle), you may have a fiber deficiency (6).

3. Lack of Blood Sugar Control

Another sign that your diet may be low in fiber is fluctuations in your blood sugar levels. Fiber, particularly soluble fiber, slows the absorption of sugar into your bloodstream, which can prevent spikes in blood glucose and insulin levels (7). 

If you're experiencing episodes of hypoglycemia (low blood glucose levels) or hyperglycemia (high blood glucose levels) despite a balanced diet, it might indicate inadequate fiber intake. Similarly, if you’ve been diagnosed with type 2 diabetes and your blood sugar levels are difficult to manage, you may need to increase your fiber intake. 

4. Mood Swings

If you aren’t getting enough fiber, you may find yourself experiencing more mood swings. This is because fiber helps to regulate the release of serotonin, a chemical that plays a role in mood regulation.

A lack of fiber can also lead to feelings of anxiety and depression, irritability, and restlessness (8).

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5. Heart Health Concerns

A low-fiber diet can also impact heart health. One of the potential signs of insufficient fiber intake is high cholesterol or blood pressure levels. Dietary fiber, particularly soluble fiber, binds with cholesterol particles in the digestive system and helps to expel them (9). 

Consequently, a diet low in fiber may increase cholesterol levels, a risk factor for heart disease. Regular cholesterol and blood pressure monitoring can indicate whether you need to increase your dietary fiber intake for better heart health. 

Any changes or concerns related to heart health should be immediately discussed with your doctor or healthcare provider. They’ll be able to give you appropriate advice based on your specific situation.

6. Chronic Inflammation

Dietary fiber plays a crucial role in maintaining gut health, regulating the immune system, and reducing inflammation markers in the body. When fiber intake is low, these delicate systems can become imbalanced—causing chronic inflammation (10).

This can potentially contribute to the development or exacerbation of chronic inflammatory conditions like Irritable Bowel Syndrome (IBS), diverticulosis, and rheumatoid arthritis.

7. Lower Energy

A low-fiber diet often comes with a noticeable decrease in energy levels. This is because dietary fiber plays a crucial role in regulating the body's use of sugars, helping to keep our energy levels at an optimum during the day. 

When we consume food high in fiber, the absorption of nutrients, including sugars, is slowed down. This allows the body to get a steady stream of energy, rather than the peaks and dips that come with a diet high in sugars and starches but low in fiber. So, if you feel tired and sluggish despite adequate rest, it could be a sign that your diet lacks sufficient fiber.

Fiber—an Important Nutrient for Overall Wellness

Fiber is a nutrient that plays a critical role in many aspects of our health. But, since many people aren’t eating the recommended servings of fruits, veggies, nuts, seeds, and other fiber-rich foods, fiber intake isn’t quite what it used to be.

Not consuming enough fiber is linked to an increased risk of obesity, heart health concerns, and even certain cancers. If you experience any of the seven symptoms mentioned in this article, take that as a sign to evaluate your fiber intake and bump it up if needed.

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Lauren Manaker
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Lauren Manaker

Lauren Manaker is an award-winning registered dietitian (RDN), certified lactation educator (CLE), author, and speaker with over 20 years of experience. She earned her BS in Food Science and Human Nutrition from the University of Florida (go Gators!) and an MS in Clinical Nutrition from Rush University in Chicago.

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    Medical Disclaimer

    This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of such advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Chad Walding nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement, or lifestyle program.

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