How Long The Digestion Process Takes From Beginning To End

The process of digestion is one that every body goes through. But exactly what happens from the time food enters your mouth to the time it exits your body may not be top of mind for most people. So how long does it really take to move from point A to point B? And why are some foods more difficult to digest than others?

Understanding how you digest your food can make it easier to comprehend why the body reacts as it does, and fueling yourself with certain ingredients can leave you lacking in energy much more quickly than other meals. From your first bite to the trip to the bathroom, we got to the bottom of everything you need to know (and likely more) about the inner workings of your digestive system.

You may be surprised to learn that digestion actually begins before you even take your first bite of food. This is called the cephalic phase of digestion and is kicked off by the mere sight or smell (or even thought or taste) of food as your body prepares to eat.

Once you've taken your first bite, the saliva in your mouth both moistens and helps digest food, for example amylase for carbohydrates and starches. As nutrition scientist Ashley Jordan Ferira, Ph.D., RDN, explains, "Along with chewing, your mouth is where digestion, or the breakdown of food into smaller bits, begins. In fact, your mouth (aka oral cavity) features its own unique set of microbes known as the oral microbiome."

From our mouth, the food, beverages, and supplements we consume journey down the pharynx and esophagus to the stomach, where they are broken down further. This continued digestion happens through unique acidic compounds, as well as protein- and fat-digesting enzymes, in the stomach. "Muscular contractions in the stomach also contribute to the digestive process," adds Ferira. From chewing our food to stomach digestion, this movement of food takes about two hours. 

Your meal, or "bolus of digested food known as chyme," Ferira explains, will then move into the small intestine via the pyloric sphincter, where digestive enzymes, many of which are secreted by the pancreas, and bile from the gallbladder break it into even smaller pieces before they are absorbed from the gut into the bloodstream to be utilized by the entire body.

"These smaller constituents being transported and utilized throughout our body are peptides that make up proteins, sugars that make up carbs, fatty acids that comprise fat, plus vitamins, minerals, and even phytonutrients," shares Ferira. "A unique array of probiotic species reside in the small intestine, also interacting with our dietary inputs," Ferira adds.

You can expect food to travel through the muscle-lined small intestine for one to five hours depending on what you've eaten (more on that later). Immediately following the small intestine is the large intestine (aka colon), where the gut musculature gradually moves along any remaining digested and undigested compounds.

The large intestine section of the gut is where another unique habitat of gut flora microbiota reside. "Of course, this assumes our dietary and supplement inputs are nourishing gut microbial abundance and diversity daily," adds Ferira.

Another important act is achieved in the colon: bulk. While significant amounts of water are absorbed from the gut into the bloodstream in the small intestine, "the final water absorption activity occurs in the colon, to functionally solidify the remaining indigestible components of our diet, creating stool," Ferira explains.

The colon is also where certain bacteria work to ferment key remaining nutritional components (e.g., prebiotic fibers) to glean any additional nutrients and "produce unique nutritional byproducts like short-chain fatty acids that confer health benefits," says Ferira. In fact, fiber consumption will directly affect how long food stays in the large intestine, and fiber assists in bulking up the stool that will then exit your body (via the rectum and finally, anus) at the end of the digestive tract.

With all that taken into consideration, it takes between 24 hours and 73 hours to digest food. This of course depends on what you've eaten alongside a variety of other factors, but it's important to start the digestive process with intention, by eating slowly, to savor your food and ensure it can move smoothly through your gastrointestinal (GI) tract.

"The fiber content1 of a food impacts how quickly it's digested," explains nutritionist Mackenzie Burgess, RDN, recipe developer at Cheerful Choices. "Foods higher in soluble fiber form a gel-like substance in the stomach, which slows down the digestive process. In contrast, foods high in insoluble fiber speed up the digestive process because they quickly pass unabsorbed into the large intestine, where they add bulk to stool." Both types of fiber are important to regularly consume, explains Ferira.

From the moment food enters your mouth to when it hits your small intestine can take between two and five hours and is known as gastric emptying. Via the small intestine, the food will be digested between two and six hours before it comes to your large intestine. This is where the food spends the longest amount of time, as it can take as short as 10 hours and as long as 59 hours to pass, explains Burgess.

"In addition to the macronutrient composition and diversity of your diet and supplement life (think prebiotic fibers and targeted probiotics), there is also individual variety from person to person when it comes to GI motility and speed,"* adds Ferira.

For example, when you've eaten foods like simple carbohydrates (think sugar or white bread), your body is able to digest this much more quickly, which is why they do not satiate you as well as more nutrient-dense foods that keep your digestive system busy for longer. "In fact digestion of simple or fast carbs starts straight away in your mouth, whereas fiber and other macronutrients remain intact," Ferira expounds.

That's right, fats and proteins move through your body at a slower rate, increasing the duration of time you feel full. "This is because proteins and fats are complex compounds that require more steps to be broken down," notes Burgess. "Fats in particular take longer to digest because they don't dissolve in water, which means an additional substance, bile, is needed for their digestion," she adds.

In fact, "a piece of steak may easily be digested for about six hours before it will go to the small intestine," adds Ella Davar, R.D., CDN.

There are a multitude of factors that can affect the speed of digestion outside of the foods you're putting into your body, from physical activity to stress. In fact, stress has been known to cause you to feel full more quickly and lead to stomach discomfort and even queasiness from slowed digestion. 

With this, poor digestion due to feelings of anxiousness or unhealthy food choices may affect your mood and body as a whole. "[Your] digestion affects not only nutrient absorption rates but also immunity, hormones, and even mental and emotional well-being," notes Davar.

Thankfully, being smart about the foods you're putting into your body, as well as your supplement routine can help improve digestion and generally allow you to feel your best. 

A diet rich in fruits and vegetables will allow digestion to flow more smoothly as these ingredients are naturally rich in fiber. "Fruits and vegetables contain both soluble and insoluble fibers that are important for maintaining a healthy gut," explains Burgess. "Soluble fiber feeds gut bacteria, which then produce substances that can support a healthy gut microbiome2." 

Ferira agrees, adding that, "consuming prebiotic fiber regularly directly fuels postbiotic abundance via fermentation processes in the gut. Not to mention the health benefits the wide array of phytonutrients in fruits and vegetables also deliver."

Incredibly healthy omega-3 fatty acids (like EPA, DHA, and ALA) are another functional nutrient that can help move food through the body more efficiently. "Omega-3s have been found3 to help maintain the proper balance of good bacteria in your gut and support the integrity of your gut wall," adds Burgess.

What's more, they are "antioxidant and anti-inflammatory powerhouse fats, especially the marine-derived EPA and DHA varieties," Ferira explains.

Regular movement and physical activity are great for a number of areas of the body, and digestion just so happens to be one of them. This is because exercise can promote motility in the gut, effectively cutting down on the time it takes for food to move through the body. "Studies show that exercise may improve gut health in many ways," says Burgess.

Seeing as digestion is a natural process that every body completes, it can be useful to understand the ins and outs in order to help things move more smoothly. To aid digestion, focusing on a nutrient-dense diet (and more specifically, fiber) and an effective targeted probiotic can help to move things along, bulk up stool, and support your overall health.*