Maybe you've been leaning heavily toward healthier, plant-based foods that are higher in fiber—like vegetables, beans, and whole grains—and you're seeing benefits like more energy and changing body composition. But there's one side effect you may not appreciate: increased flatulence.
Turns out, that may actually be a sign that your gut bacteria is happy with your diet changes, according to a new study published in the journal Nutrients.
Researchers recruited 18 healthy, adult male volunteers and had them eat a Western-style diet high in processed carbs and low in fiber for two weeks. Then, they switched to a plant-based Mediterranean diet for the next two weeks.
In assessing effects on stool and gas, the change to a high-fiber, plant-based diet produced significant indications that gut health had changed. Participants had double the stool size and about 50% more gas, and researchers concluded this was due to a huge increase in the mass of beneficial bacterial growth in the digestive system.
With more plant material in the gut, the bacteria kicked off more fermentation, and that gas buildup turned into flatulence.
Another study, in the journal mSystems, confirms that it doesn't take long to see changes in gut bacteria composition when switching to a high-fiber diet. In that research, which used mainly unprocessed, high-fiber foods, participants had considerable and beneficial bacteria shifts in only about two weeks, similar to the recent study.
But, as the research on gassy effects suggests, the body may go through a transition period as it attempts to adjust. This is very common, according to Tamara Duker Freuman, RD, and author of "The Bloated Belly Whisperer."
"When you add a lot of healthy options to your diet, especially with fiber, it can cause digestive issues if you try to do too much, too soon," she says. That can lead to gas, bloating, discomfort, and sometimes even abdominal cramping and diarrhea. Your body will adjust over time, she adds, but it's better to ramp up slowly to prevent these issues.
As you pivot toward healthy foods, Freuman says it's helpful to focus mainly on whole foods and integrate processed foods more slowly. That's because choices like nut flours, bean pastas, and cauliflower pizza crusts can increase your fiber intake significantly.
When you begin to have issues such as flatulence, it may be a sign that your gut health is getting on track—but it's also an indication you might need to dial back the fiber a bit so your body has time to adjust.