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- Most Americans don’t get nearly enough fiber, and diets lacking whole grains and fruits, like the keto diet, can also make fiber difficult to consume.
- A lack of fiber can mean an unhealthy digestive system, which can lead to both short and long-term health complications.
- Low-fiber diets have been linked to dangers like colon cancer, unhealthy cholesterol levels, and diverticulosis.
- Focus on fruits, vegetables, whole grains, and legumes to up your fiber intake gradually, and make sure you increase your water consumption, too.
Fiber promotes regularity and satiety, but it does a lot more for your health than that. For instance, consuming the right amount of fiber regularly also helps slow down blood sugar response and manage cholesterol levels.
Problem is, most Americans only get about half the recommended dose of fiber, which is 25 to 30 grams per day from food (not supplements), according to UCSF Health. To make things worse, popular diets like keto make it extra hard to get enough fiber, which is mostly found in fruits, vegetables, legumes and whole grains – foods the diet limits or forbids.
So before you dive into more processed foods and fewer fruits, consider these risks of a low-fiber diet.
Too little fiber can cause constipation
“Fiber is good to help regulate the digestive system and to help move the food along the gastrointestinal tract,” Emily Tills, a registered dietitian in New York state told INSIDER. When we don’t have enough fiber in our diet, she said, we can experience severe constipation, which can cause pain, bloating, and sometimes even hospitalization and surgery.
A low-fiber diet can cause diverticulosis
“Without adequate fiber, the digestive tract can lose its muscle tone,” said Seattle-based registered dietitian Liz Wyosnick. That can lead to diverticulosis, an incurable condition in which small pouches develop in the wall of the digestive tract. Diverticulosis is uncommon in parts of the world where people eat plenty of grains, fruits, and vegetables, the American Society for Gastrointestinal Endoscopy reports.
Low-fiber intake can cause loose stools
“Our gut microbiome feeds off short-chain fatty acids, which are synthesized from resistant starches from plant-based foods high in soluble fiber like grains, fruits, and vegetables,” said New York City-based registered dietitian Rachel Fine.
Since these acids help to absorb water in the colon, inadequate production from low fiber intake can result in the passing of excess water, which leads to loose stools.
Low-fiber intake can mess up your blood sugar levels
Research shows that eating fiber-rich foods can help slow your blood sugar response after a meal, which is especially beneficial to people with diabetes,” said San Diego-based registered dietitian Elizabeth Ann Shaw. A low-fiber diet can do just the opposite, causing that meal to have an immediate effect on your blood sugar. Over time, constant blood sugar spikes can lead to complications, including diabetes.
Low-fiber diets may raise the risk of colon cancer
Over the years, hard stools and irregular bathroom patterns – which a low-fiber diet can induce – “can add up to conditions that are right for cancerous polyps to grow,” said registered dietitian Laura Yautz, who’s based in Pittsburgh. On the flip side, research has linked diets high in fiber from cereals and fruit with a reduced risk of colon cancers. While some colon cancers are genetic, Yautz said, the majority are related to poor lifestyle habits.
Without enough fiber, it’s hard to fight inflammation
Chronic inflammation in the body will eventually end up as a disease, so it’s vital to make sure you eat foods that fight inflammation – or those with antioxidant properties – frequently, Yautz said. The foods with the most antioxidant properties are plants (fruits, vegetables, and whole grains), since they contain naturally occurring fiber.
A low-fiber diet can disrupt the microbiome, leading to chronic health issues
“Fiber is the main food source for the good bacteria in our gut,” Yautz said. Without it, they die, she explained, and your gut can become overrun with more harmful bacteria that can cause myriad health problems. Some research suggests, for instance, that unbalanced gut bacteria can lead to inflammatory bowel disease, obesity, and cancer. It’s best to eat fiber from different types of foods to keep the good guys fighting in your corner, Yautz said.
A low-fiber diet isn’t helping your PMS symptoms
Some PMS symptoms seem to be related to hormonal changes, like an increase in estrogen. A low-fiber diet doesn’t help: “Excess estrogen is more aptly eliminated with the help of fiber, and a moving digestive system,” said Wyosnick, who makes sure to discuss fiber intake with patients who experience significant PMS.
Not enough fiber may make it harder to control your weight
“Fiber is absolutely imperative because it provides a volume within meals for little-to-no calories, fat, or sodium,” Wyosnick explained. In other words, adding a giant salad, two cups of roasted broccoli, or shredded cabbage to your curry dish can provide more volume within your meal, help to distend the stomach, and signal to your brain that you have been adequately fed, she said.
A low-fiber diet can negatively affect your cholesterol levels
Fiber can also help lower your cholesterol levels, Tills said. A diet high in soluble fiber, or the type found in oatmeal, for instance, can help pull out cholesterol from the liver and excrete it, she said. Skimping on the nutrient, on the other hand, is associated with lower levels of HDL (good) cholesterol.
Ready to load up on fiber? Be sure you add both soluble fiber (whole grains, oats, beans) and insoluble fiber (skins of fruit and non-starchy vegetables) to your everyday diet, Wyosnick said. You can think of soluble fiber as the bulking agent that helps to exercise the gastrointestinal tract, she said, and insoluble fiber as the pipe cleaner that sweeps the surface to move things along.
Drink plenty of water, too. “The important things to keep in mind if you want to increase your fiber intake is to increase gradually, and drink plenty of water,” Wyosnick said.