Farting releases gas that builds up in your digestive tract, preventing uncomfortable pressure from accumulating in your intestines. It’s a basic bodily function that happens 14 to 23 times a day in most healthy adults, and it serves as both a pressure valve and a byproduct of normal digestion.
How Gas Builds Up in Your Body
Gas enters and forms in your digestive tract through two main routes. The first is swallowed air. Every time you eat, drink, or even swallow saliva, small amounts of air travel down into your stomach. Some of that air gets belched back up, but whatever remains moves deeper into the intestines and eventually exits as flatulence.
The second, larger source is bacterial fermentation. Your large intestine is home to trillions of microorganisms that help break down food your stomach and small intestine couldn’t fully digest, particularly certain carbohydrates like fiber, starches, and some sugars. As these bacteria do their work, they produce gas as a byproduct. This is why foods like beans, broccoli, cabbage, and whole grains tend to make you gassier: they contain more of the complex carbohydrates that feed gut bacteria.
What Farting Actually Does for You
The primary job of flatulence is pressure relief. Your intestines produce between 500 and 2,000 milliliters of gas every day. That’s roughly one to four pint glasses’ worth. If that gas had nowhere to go, it would distend the walls of your intestines, causing bloating, cramping, and pain. Passing gas prevents that buildup and keeps things moving comfortably through your digestive system.
Farting is also a sign that your gut microbiome is active and doing its job. Research suggests that increased gas production after switching to a high-fiber, whole-foods diet is actually an encouraging indicator of a healthy, active microbial community in your gut. In other words, more gas from fiber-rich foods often means your gut bacteria are thriving, not that something is wrong.
What’s in a Fart
About 99% of the gas you pass is completely odorless. It’s made up of five gases: nitrogen (which can range from 11% to 92% of the total), carbon dioxide, hydrogen, methane, and small amounts of oxygen. The proportions vary wildly from person to person and even from one fart to the next.
The smell comes from the remaining 1%, primarily hydrogen sulfide, the same compound responsible for the rotten-egg odor. Certain gut bacteria produce hydrogen sulfide by breaking down sulfur-containing compounds found in foods like eggs, meat, garlic, and cruciferous vegetables. Sulfate, a compound naturally present in various foods and drinking water, also contributes. So the intensity of the smell depends largely on what you’ve been eating and which bacteria are most active in your gut.
What Makes the Sound
The sound of a fart works on the same principle as buzzing your lips into a trumpet mouthpiece. As gas passes through the anal sphincter, it causes the surrounding skin to vibrate. The pitch and volume depend on several factors: the speed of the gas, the tightness of the sphincter, and the volume of gas being released. A small amount of gas escaping slowly through a relaxed sphincter may be nearly silent, while a larger burst through a tighter opening produces the classic sound.
What Happens if You Hold It In
Suppressing a fart won’t cause any lasting damage, but it’s not exactly comfortable. The trapped gas stretches the intestinal walls, which can lead to bloating, abdominal pain, and nausea. If you keep holding it, the gas doesn’t just sit there forever. It gets reabsorbed into your bloodstream and eventually makes its way to your lungs, where you literally breathe it out. So the gas leaves your body one way or another.
When Gas Signals Something Else
Passing gas up to 23 times a day falls within the normal range. But a persistent, noticeable increase in volume, frequency, or smell, especially when paired with other symptoms like diarrhea, constipation, weight loss, or abdominal pain, can point to digestive conditions where food isn’t being properly broken down or absorbed. Lactose intolerance is a common example: undigested lactose reaches the large intestine and gets fermented rapidly, producing excess gas. Conditions like irritable bowel syndrome and celiac disease can produce similar patterns.
The key distinction is context. A gassy afternoon after eating a bean-heavy lunch is your gut working exactly as designed. Weeks of excessive, foul-smelling gas with no clear dietary explanation is worth paying attention to.