The #1 Habit to Break for Better Gut Health, According to Registered Dietitians

Microbes are everywhere, and all sorts of them enter our bodies every day—including through the food we eat. (It might sound gross, but it's a normal and natural part of life.) When a meal makes its way through our digestive tract, the microbes in the food look for a place to settle—namely in your GI tract. Some of these bugs are beneficial to health, while others may contribute to the onset of certain diseases. Together, this community of bacteria, both the good and bad bugs, make up your microbiome. And how healthy your gut is largely depends on the microbiome residing there.

Good bacteria can help you digest and absorb nutrients, produce short-chain fatty acids that the body uses for energy, make vitamins such as K and B12, and protect your gut lining by warding off harmful substances.

On the flip side, the harmful kind of gut bacteria can trigger inflammation, leading to cramps, bloating and abdominal pain. There is a growing body of evidence that suggests irritable bowel syndrome and inflammatory bowel disease result from the imbalance of good and bad bacteria. This imbalance can also cause chronic conditions such as heart disease and diabetes.

Numerous factors affect your microbiome, including your activity level, how well you manage stress, illnesses, what you eat and certain medications, according to a 2019 review article published in Nature Reviews Gastroenterology & Hepatology. And that brings us to the biggest habit dietitians say you should break for better gut health: slashing carbs. So many people today are focused on cutting out this macronutrient in the name of health and perhaps achieving a lower number on the scale. But our pros say that's not the way to go.

How a Low-Carb Diet Affects Gut Health

Carbohydrates, specifically the type found in vegetables, fruits, whole grains and legumes, are a source of prebiotics—a group of nutrients (often fiber) that act as food for your gut microbiota. Prebiotics include inulin, fructo-oligosaccharides, resistant starch and beta-glucans. They're typically indigestible, and pass through your GI. tract and into your colon. Along the way your gut bugs feed on them and, in turn, produce short-chain fatty acids, synthesize vitamins and perform other beneficial functions.

The prebiotics and other bioactive compounds in plant foods like these may enrich specific types of microbes, increasing the diversity of microbes in your gut, according to a 2020 study published in the International Journal of Food Science and Nutrition. So the greater the variety of whole plant-based foods you consume, the wider array of good bacteria you'll likely have living in your gut, according to Kim Kulp, RDN, a San Francisco-based dietitian and owner of Gut Health Connection. That diversity of microbes may also protect the intestinal lining and reduce inflammation, which could lower the risk of chronic diseases, she adds.

In other words, when you cut back on carbs and eat too little fiber, you will limit the diversity of prebiotics, and could starve your good bacteria and allow the bad bacteria to flourish. This could lead to dysbiosis, or an imbalance of the microbes existing in the gut.

With fewer beneficial microbes residing in the gut providing energy for our colonic cells and protecting the intestinal lining, we may be more prone to irritable bowel syndrome, allergies and other chronic diseases, according to 2021 research published in Frontiers in Endocrinology.

How Many Carbs Do You Need to Eat for a Healthy Gut?

Researchers haven't yet identified a "perfect" mix of gut bacteria that you should tailor your diet to. But what is known is that a healthy gut is about the types of foods you eat rather than the quantity of carbs. So Kulp recommends eating a healthy diet that (yes) includes beneficial carbs. Focus on including a variety of whole grains, vegetables, fruits, legumes, nuts and seeds. (Think: The USDA's MyPlate recommendation to fill half your plate with fruits and veggies, one quarter with whole grains and the other quarter with lean protein.)

And try switching it up! For instance, instead of just eating one or two types of grains, like brown rice and oats, Kulp suggests trying quinoa, buckwheat, barley and other fiber-rich foods. "Just like us, different microbes have different food preferences," she adds.

Other Tips and Tricks for a Healthy Gut

Eat at Consistent Times

In addition to focusing on providing a variety of foods, Liz McMahon, M.P.H., RDN, LDN, a Philadelphia-based gut-health dietitian and owner of Liz McMahon Nutrition, recommends sticking to regular mealtimes as much as possible.

The reason is that the gut microbiome may also influence your circadian rhythm (your body's internal clock) and metabolism, according to a 2020 article published in Nature Reviews Endocrinology. And that may affect how your body uses nutrients from the foods you eat and could impact blood glucose and lipid levels, as well as insulin sensitivity.

Leigh Merotto, RD, M.H.Sc., a Toronto-based dietitian and owner of Leigh Merotto Nutrition, agrees. She says that most people should eat every three to four hours to support stable blood sugar levels. If you are busy or don't have a consistent schedule, McMahon adds that you can set a time range you can work within and still eat your meals. For example, breakfast can be between 7 and 9 a.m., lunch between 11:30 a.m. and 1:30 p.m. and so on.

And if you know you have a consistent schedule every day, say a meeting at 2 p.m., McMahon recommends setting the alarm for 1 p.m. to ensure you get your lunch in. If you travel frequently, keep healthy snacks with you so you don't go hours without eating. (Check out our 21 Simple Meal Prep Ideas to Help Support Gut Health if you are always on the go.)

Stop the Feast-and-Famine Cycles

By having meals and snacks at consistent times throughout the day, you may avoid the tendency to overeat (because you're ravenous) and also will be more likely to get the array of nutrients you need for good gut health. "If you are only feeding your body once or twice a day, you are likely taking in way too much food in one sitting, which is difficult to digest and can lead to bloating and discomfort," adds McMahon.

Amanda Sauceda, M.S., RDN, a registered dietitian in Long Beach, California, who specializes in gut health, says it's not wise to eat a lot of one type of food one day and then little to none the next, especially fiber. She says that when you have not been eating a lot of fiber, and suddenly you eat a large amount, you may notice digestive discomfort.

She advises adding fiber slowly and gradually, and drinking water to keep the contents moving along the gut. The 2020-2025 Dietary Guidelines recommends that women ages 19 to 30 get at least 28 grams of fiber per day, those 31 to 50 consume 25 grams, and those 51 and up get 22 grams daily. For men, the fiber recommendations are 34 grams per day for those ages 19 to 30, 31 grams for those 31 to 50, and 28 grams for those 51 and older.

Bottom Line

While your lifestyle habits, activity level, medications and illness can affect your gut health, what you eat remains one of the key determinants. Fueling your body with an array of nutritious foods, particularly carbs rich in prebiotics, could help create a diverse gut microbiome that protects your gut and supports good health. Eating appropriate portions throughout the day also helps control blood sugar and maintains consistent energy levels. It is never too late to get started on improving and maintaining a healthy gut. Browse our 1,500-calorie and 2,000-calorie meal plans for inspiration, and speak with a registered dietitian to get customized advice for specific gut-health-related concerns.