Signs You're Not Getting Enough Fiber (And What to Do About It)

Reviewed by Dr. Kathleen Valenton, MD, Double-Board Certified OB/GYN

Published: March 20, 2026  |  9 min read

Fiber is one of the most under-consumed nutrients in the American diet. According to the Dietary Guidelines for Americans, more than 90% of women fail to meet the recommended daily intake of 25 grams. Most of us are getting somewhere around 15 grams per day -- a gap that has real, measurable effects on how we feel, how our gut functions, and how our broader health holds up over time.

The tricky thing about low fiber intake is that the signs are easy to dismiss as unrelated problems. You might chalk up your sluggish digestion to stress, your energy crash to poor sleep, or your constant hunger to willpower. But in many cases, fiber is the missing piece. Here is how to recognize the signs and what to do about them.

Sign 1: You Are Constipated or Irregularly

This is the most well-known sign of low fiber intake -- and the most directly related. Fiber, particularly insoluble fiber, adds bulk to stool and helps it move through the digestive tract efficiently. Without adequate fiber, waste moves more slowly, stool becomes harder and drier, and bowel movements become infrequent or difficult.

Mayo Clinic identifies fiber as one of the most important dietary tools for preventing and relieving constipation, noting that insoluble fiber from whole grains, nuts, and vegetables acts as a natural bulking agent in the gut. If you are having fewer than three bowel movements per week, or if straining is a regular occurrence, low fiber intake is one of the first things to consider.

Chronic straining also raises the risk of hemorrhoids, a condition that the Cleveland Clinic specifically links to insufficient dietary fiber. A higher-fiber diet that produces soft, well-formed stools dramatically reduces hemorrhoid risk.

Sign 2: You Feel Hungry Shortly After Eating

If you find yourself reaching for food again within an hour or two of a full meal, fiber may be the missing ingredient in that meal. Soluble fiber slows gastric emptying -- the rate at which food leaves the stomach -- which extends feelings of fullness after eating.

Research published in the Journal of the American College of Nutrition found that dietary fiber intake is consistently associated with lower body weight, largely through its role in satiety. When soluble fiber dissolves in water in the digestive tract, it forms a gel-like substance that keeps you fuller for longer and blunts the blood sugar spikes that trigger hunger rebounds.

High-fiber meals tend to be more satisfying per calorie than low-fiber, processed-food alternatives. If constant hunger feels like a battle you are constantly losing, it may not be about willpower. It may be about fiber.

Sign 3: You Have Energy Crashes During the Day

Blood sugar instability is a common cause of afternoon energy crashes, brain fog, and the mid-day fatigue that many women experience. And fiber plays a direct role in blood sugar regulation.

Soluble fiber slows the absorption of glucose from food into the bloodstream, reducing the sharp spike-and-crash pattern that follows high-carbohydrate, low-fiber meals. Without enough fiber, glucose absorption is rapid and blood sugar rises sharply, triggering a compensatory insulin response that can leave you feeling depleted within hours of eating.

If your energy feels inconsistent throughout the day -- particularly after meals -- increasing your fiber intake alongside protein and healthy fats is one of the most effective dietary strategies for achieving more stable energy levels.

Sign 4: Your Gut Feels Bloated or Uncomfortable

Paradoxically, both too little fiber and sudden increases in fiber can cause bloating. But chronic low fiber intake creates its own kind of digestive discomfort: sluggish transit, a feeling of heaviness, and a gut environment where harmful bacteria can outcompete beneficial ones.

Prebiotic fiber specifically feeds the beneficial bacteria in the gut, supporting a balanced microbiome. When beneficial bacteria are undernourished, the gut microbiome can shift in ways that increase gas production, bloating, and irregular bowel habits. Gradually increasing fiber intake -- rather than going from zero to 25 grams overnight -- is the key to avoiding the transitional discomfort that can come with dietary changes.

The Cleveland Clinic notes that processed foods, which are consistently low in fiber, are a common driver of bloating because they lack the fiber needed to support healthy gut motility and microbiome balance.

Sign 5: Your Cholesterol Numbers Are High

Soluble fiber has a well-documented role in cholesterol management. It binds to bile acids in the digestive tract, interrupting the recycling process and prompting the liver to pull cholesterol from the bloodstream to make new bile. The net effect is a reduction in LDL, often called bad cholesterol.

Mayo Clinic specifically lists fiber-rich foods including oatmeal, oat bran, flaxseed, beans, apples, and pears as evidence-backed tools for lowering LDL cholesterol levels. If your lipid panel has been trending in the wrong direction, your fiber intake is worth evaluating alongside other dietary factors.

Sign 6: You Are Gaining Weight Gradually Without a Clear Cause

When satiety signals are weak, hunger returns faster, portion sizes creep up, and caloric intake increases over time without dramatic dietary changes. Low fiber diets are associated with higher overall caloric intake in epidemiological studies -- not because people are eating dramatically more, but because high-fiber foods are more filling per calorie than low-fiber alternatives.

Research from PubMed shows that consuming an additional 14 grams per day of fiber over several months is associated with modest reductions in energy intake and body weight, without caloric restriction. The mechanism is largely satiety: when you are genuinely fuller for longer, you eat less naturally.

Sign 7: Your Skin or Mood Seems Off

This one surprises people, but the gut-brain and gut-skin axes are real and well-researched. The gut microbiome, which is directly nourished by dietary fiber, communicates with the brain through the vagus nerve and influences the production of serotonin -- approximately 90% of which is produced in the gut, not the brain.

Research on the gut-brain axis shows that microbiome imbalance is associated with mood disruption, anxiety, and low-grade inflammation. Similarly, gut health is connected to skin clarity through the inflammatory pathways regulated by gut bacteria. A fiber-deprived diet can quietly undermine the gut ecosystem that keeps these systems in balance.

What to Do About Low Fiber Intake

Start with Whole Foods

The best fiber sources are always whole foods. Here are high-fiber options that are easy to incorporate:

•   Legumes: lentils, black beans, chickpeas (15-17g per cup)

•   Vegetables: broccoli, Brussels sprouts, carrots, artichokes (4-7g per cup)

•   Fruits: raspberries, pears, avocados, apples (4-8g per serving)

•   Whole grains: oats, quinoa, whole wheat, barley (3-6g per serving)

•   Seeds: chia seeds, flaxseeds, hemp seeds (5-10g per two tablespoons)

Track Your Intake for One Week

Most people dramatically overestimate how much fiber they are getting. Use a simple food tracking app for one week to see your true baseline. The number is often surprising -- and motivating.

Add a Fiber Supplement to Fill the Gap

For women who consistently fall short of 25 grams per day through food alone -- which, statistically, is most of us -- a quality fiber supplement can bridge the gap without adding significant calories or preparation time. Lemme Fiber Gummies, named Oprah's Favorite Fiber Supplement in the Oprah Daily 2026 Self-Care O-wards, deliver 4 grams of non-GMO prebiotic FOS fiber per serving, along with two clinically studied probiotic strains and 100% Daily Value of Vitamin D3. No added sugar, no gelatin, vegan-friendly.

Lemme Fiber is available at lemmelive.com, Target, Ulta, Walmart, and Amazon.

Increase Gradually and Drink Water

The most common mistake when increasing fiber intake is doing it too quickly. Adding large amounts of fiber in a short period can cause temporary bloating, gas, or cramping as the gut microbiome adjusts. The key is to increase gradually -- adding approximately 5 grams of additional fiber per week -- while drinking plenty of water throughout the day to support fiber's effectiveness.

The Bottom Line

Low fiber intake is one of the most common and consequential nutritional gaps in women's diets -- and its effects show up in ways that are easy to misattribute to other causes. Constipation, constant hunger, energy crashes, bloating, high cholesterol, gradual weight gain, and even mood disruption can all be connected to inadequate fiber. The good news is that the gap is closeable, and even modest increases in fiber intake can produce meaningful changes in how you feel.

Start with whole foods, supplement where needed, and increase gradually. Your gut, your hormones, and your energy levels will all respond.

Frequently Asked Questions

How quickly will I notice changes after increasing my fiber intake?

Digestive improvements, including more regular bowel movements and reduced constipation, can be noticeable within a few days to one week of consistently increasing fiber intake. Gut microbiome changes in response to increased prebiotic fiber have been documented within two to four weeks in research studies.

Can low fiber intake affect my hormonal health?

Yes. The gut microbiome plays a direct role in estrogen metabolism, influencing how the body processes and regulates hormones. A fiber-depleted gut microbiome can impair this process. For women navigating hormonal fluctuations at any life stage, maintaining adequate fiber intake is part of supporting the gut-hormone connection.

Is 25 grams of fiber per day the right goal for everyone?

The Dietary Guidelines for Americans recommend approximately 25 grams per day for adult women under 50, and slightly less for women over 50. These are population-level targets, and individual needs can vary. Women with conditions like IBS, Crohn's disease, or other gastrointestinal disorders should work with their healthcare provider to determine the appropriate fiber intake and types for their specific situation.

Can I get enough fiber from a supplement alone?

Fiber supplements are designed to complement a whole-food diet, not replace it. Whole foods contain a complex matrix of nutrients, polyphenols, and different fiber types that work synergistically in ways that a single-ingredient supplement cannot replicate. Lemme Fiber, for example, contributes 4 grams of prebiotic fiber per serving -- a meaningful contribution toward the 25-gram daily goal, but most effectively used alongside a varied, plant-rich diet.

What type of fiber supplement is best for women?

Look for a supplement that includes prebiotic fiber to nourish beneficial gut bacteria, named probiotic strains if the product includes probiotics, no added sugar, and no gelatin. Lemme Fiber checks all of these boxes while adding 100% Daily Value of Vitamin D3 -- a nutrient many women are deficient in, particularly after 40.

This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any new supplement regimen.

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.

Citations

1. U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. https://www.dietaryguidelines.gov/

2. Mayo Clinic. Dietary fiber: Essential for a healthy diet. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983

3. Cleveland Clinic. Bloated stomach: Causes, tips to reduce, and when to be concerned. https://my.clevelandclinic.org/health/symptoms/21740-bloated-stomach

4. Clark MJ, Slavin JL. The effect of fiber on satiety and food intake: a systematic review. Journal of the American College of Nutrition. 2013;32(3):200-211. PubMed PMID: 23885994.

5. Daley S, Shreenath A. The role of dietary fiber in health promotion and disease prevention. StatPearls. Updated December 2025. NCBI Bookshelf NBK559033.

6. Sanz Y, Cryan JF, et al. The gut microbiome connects nutrition and human health. Nature Reviews Gastroenterology and Hepatology. 2025;22(8):534-555. https://doi.org/10.1038/s41575-025-01077-5

About the Expert Reviewer

Kathleen Valenton, MD is a double board-certified OB/GYN at Rodeo Drive Women's Health Center in Beverly Hills, CA, with over a decade of experience in women's health. She completed her internship and residency at Cedars-Sinai Medical Center -- where she remains an attending physician -- after earning her Medical Degree from the University of Vermont College of Medicine and dual Bachelor's and Master's degrees in Psychology from UC Berkeley. Dr. Valenton is also the Chief Medical Officer at Lemme. Her clinical research interests span mental health, hormonal health, infertility, PCOS, and menopause. Dr. Valenton is known for her expertise in pelvic pain, infertility evaluations, and minimally invasive surgery, and remains actively involved in resident education and physician-nursing collaboratives at Cedars-Sinai.