Experts break down everything you need to know about this superstar nutrient, including how much of it you should be eating each day. 
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These Benefits of Fiber Make It the Most Important Nutrient In Your Diet
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While there are plenty of reasons why your parents used to force you to eat your veggies, odds are their rich fiber content was one of them. A powerhouse nutrient, fiber stands out for its ability to keep your digestion system running smoothly, fill you up for hours, stabilize your blood sugar, and more. Despite its impressive lineup of health benefits, though, recent research suggests that only 7 percent (!!) of adults in the U.S. are getting the recommended daily amount for fiber. 

Given this stat, odds are you (and many other folks) could use a refresher on fiber — after all, you're only human. Here, experts break down everything you need to know about fiber, including how much you should be getting per day and all of the reasons to fill up on this nutrient in the first place. 

What Is Fiber, Exactly?

So, you've been told to eat more fiber. But what is it, really? A type of carbohydrate, dietary fiber is essentially the structural part of plant foods (e.g. fruits, veggies, grains) that your body cannot digest or break down, according to the Mayo Clinic. As such, it passes relatively intact through your gut and out of your colon. But don't be fooled; just because it doesn't break down into sugar molecules like other carbohydrates, fiber still does a whole lot of work as it moves through your body. Before getting into those specifics, however, there are a few more facts about the powerful nutrient that you should know.

Fiber is often classified as either soluble — meaning it dissolves in water — or insoluble — meaning it doesn't dissolve in water. When soluble fiber comes into contact with H2O and other fluids in your gut, it forms a gel-like substance that takes up physical space in your stomach, thereby making foods with this type of fiber (e.g. oats, walnuts, beans, farro) especially filling. This type of fiber can also help lower blood cholesterol and glucose levels. Then there's insoluble fiber, which adds bulk to stool, stimulates intestinal movement to push it through your system, and, in turn, helps you stay regular. Cauliflower, artichokes, okra, and whole-wheat flour are some of the foods full of insoluble fiber.

Simply put, both types of fiber help food pass through your system, which is where the nutrient's potency lies: "Fiber slows down the digestion and absorption of food, so you get steady energy that lasts," says Sarah Romotsky, R.D. But that's just one of the many benefits of fiber — and here are some more.

Health Benefits of Fiber

Helps Maintain a Healthy Weight

Fiber revs your metabolism. (That's why it's one of the most important nutrients for weight loss.) Women who substitute high-fiber grains for refined ones have a higher resting metabolic rate, which means they burn more calories throughout the day, according to research published in the American Journal of Clinical Nutrition. This effect is probably due to the increased energy your body has when it gets enough fiber, along with a steady blood sugar level, says study author Susan B. Roberts, a senior scientist at the USDA Human Nutrition Research Center on Aging at Tufts University and the founder of the iDiet weight-loss program.

Fiber is especially beneficial for keeping your weight healthy because it produces short-chain fatty acids when it's broken down by your gut bacteria, says Wendy Dahl, Ph.D., an associate professor of Nutritional Sciences at the University of Florida. These fatty acids help induce feelings of fullness and keep you satiated for hours. BTW, that's just one way in which fiber can help you steer clear of cravings and dreaded hanger. (Related: These Dietitian-Approved High-Fiber Snacks Will Keep Your Stomach from Rumbling)

Stabilizes Blood Sugar

By forming that gel-like substance in your gut, soluble fiber can also slow down the absorption of carbohydrates, thereby preventing blood sugar spikes, Grace Clark-Hibbs, M.D.A., R.D.N., registered dietitian and founder of Nutrition with Grace, previously told Shape. And this is a pretty big deal because blood sugar regulation is key for staving off type 2 diabetes. What's more, the more stable your blood sugar levels, the less likely you are to experience those dreaded sugar highs and lows and, instead, keep on trucking with a steady stream of energy.

Helps Lower Cholesterol

In addition to helping manage blood sugar levels and, thus, prevent diabetes, soluble fiber can also help stave off heart disease. How, exactly? Soluble fiber binds with LDL ("bad") cholesterol in the digestive system, keeping it from entering the bloodstream and traveling to other parts of the body. When the fiber is ultimately excreted in the feces, it brings along the cholesterol, thereby preventing your body from absorbing the "bad" stuff. This also reduces blood levels of LDL cholesterol, which is associated with a lower risk for heart disease, registered dietitian Ashley Marolo, R.D., previously told Shape.

Keeps Your Body Balanced

If you're packing in a lot of post-workout protein to help build and maintain muscle, fiber can be an important counterbalance, says Dahl. Here's why: If you consume too much protein, some of it may not be digested and will instead be broken down by gut bacteria, which creates inflammation-causing compounds, she explains. But when you eat enough fiber, the nutrient acts as a deterrent. The bacteria break it down instead, which prevents this harmful process. For the best results, make sure that at least some of your daily protein comes from plant sources, such as beans and peas, that contain plenty of fiber, notes Dahl. (These vegetarian dinners are high in protein and fiber.)

Supports Healthy Digestion

If you're struggling to go number two, you might want to fill up on fiber. As mentioned above, insoluble fiber increases fecal bulk and promotes intestinal movements, which can ultimately alleviate constipation, according to the Mayo Clinic. Or maybe you have the opposite problem and are dealing with diarrhea. Soluble fiber can help with that, as it's known to firm up stool, which, in turn, can curb any loose, watery number twos. What's more, fiber can also act like a prebiotic, meaning it feeds the friendly or "good" bacteria in the gut, Valerie Agyeman, R.D., founder of Flourish Heights, previously told Shape. As such, the nutrient can help prevent symptoms of gut dysbiosis (aka an imbalanced gut), including abdominal pain, cramps, and diarrhea.

Strengthens Bones

Fiber boosts the population of good gut bugs in your digestive tract, which research has linked to a bolstered immune system and even a better mood, says Dahl. (Really-gut health and happiness go hand in hand.) Your bones benefit too. Certain types of fiber, such as chicory root, make it easier for your body to absorb magnesium and calcium — both of which are critical for a strong frame. A fiber-rich diet can even help ward off knee problems. In a 2018 study, people who ate the most fiber were less likely than people who consumed less fiber to experience worsening knee pain or develop painful osteoarthritis in their knees later, probably thanks to fiber's anti-inflammatory benefits, according to the researchers.

So, How Much Fiber Do You Really Need?

To reap the benefits of fiber, the Mayo Clinic recommends that women aim for at least 21-25 grams of fiber per day and men for 30-38 grams per day. It's important to note, however, that these numbers can vary depending on age, medical conditions, etc. Eat a variety of fruits, vegetables, whole grains, beans, and nuts, and you'll end up with the right mix of different types of fiber, says Romotsky. (Try these recipes using high-fiber foods.) And as you up your fiber intake, remember to drink more water to prevent stomach upset, she says. (See also: How Much Water Do You Actually Need Every Day Per Day?)

FYI, some packaged foods contain "functional fiber," like psyllium and inulin. While it's okay to eat this type to help fill the gaps, eating whole foods gives you the benefit of fiber plus other nutrients as well. (And, in case you were wondering, this is what you need to know about having too much fiber in your diet.)