Have you ever wondered, “how long does it take to digest food?” Digestion is a complex phenomenon. On average, it takes 24-72 hours for food to move completely through the gastrointestinal tract.1 Read on to learn about how long the digestive process takes — and what happens to your food after you swallow it.
Why Is Digestion Important?
In order for your body to function properly and remain healthy, it needs to extract nutrients from the food and drink that you consume. The job of your digestive system is to break down these nutrients into small parts that can then be absorbed and used for energy, growth, and cell repair.2
How Does The Digestion Process Work?
Digestion involves two components: mechanical and chemical. Mechanical digestion refers to grinding food into smaller pieces with your teeth or squeezing it by peristaltic contractions within the stomach. Chemical digestion refers to its breakdown by digestive enzymes in the saliva, stomach, and small intestine.3
The Oral Stage Of Digestion
The first stage of digestion is the oral stage. In this stage, chemicals in your saliva begin to break down starches in the undigested food into sugars. They also begin the breakdown process of triglycerides, which are made of fatty acids. At this point, the partially digested food is transported down the esophagus, where it passes through the esophageal sphincter to the stomach.4
The Gastric Stage Of Digestion
In the gastric stage of digestion, swallowed food bits and semi-digested proteins trigger digestive activity in the stomach. Both mechanical and chemical processes occur here, as the proteins are broken down into smaller peptides and amino acids. These food particles cause the stomach to stretch and its acidity to go down, which triggers stomach acid to be released to break apart the food. This phase accounts for about two-thirds of all gastric juices that occur during digestion.5
The Intestinal Stage Of Digestion
In this stage, the food, now called chyme, enters the small intestine via the pyloric sphincter. The stomach acid and semi-digested fats cause another muscle reflex to occur. The purpose of this reflex is to slow down how much chyme is coming into the intestinal tract. This enables the small intestine to neutralize the stomach acid and absorb the nutrients that are coming in before more chyme comes in.6
What Factors Affect The Length of Digestion?
It generally takes 1-3 days for food to fully move from your mouth to the end of your large intestine, by the anus. This is known as bowel transit time.7
Two major factors that determine the length of your digestion include:
- The complexity of the food: Simpler, less processed foods are easier to digest than more complex, processed foods.
- The macronutrient content of the food: Foods high in fat, protein, and complex sugars take longer to digest than foods that are lower in these.8
Additional factors include:
- Age: As you age, your digestive system slows down.9
- Sleep: Eating too close to bedtime may result in diminished digestive health and restless sleep.10
- Stress level: High stress levels may cause digestion to slow down or stop while the body expends energy dealing with perceived threats.11
- Water intake: Drinking too little water or eating foods with too little water content means less saliva to moisten food while chewing — and fewer digestive enzymes to break down a meal.12
- Activity level: Exercising regularly and partaking in physical activity may help support your digestive tract by making your gut muscles more efficient.13
- Gender: Average digestion transit time varies by gender, from about 33 hours for men to about 47 hours for women.14
Each of the three macronutrients, carbohydrates, fat, and protein, takes a different amount of time to digest, with fats taking the longest. In theory, this should make it easy to determine digestion time. However, we rarely eat macronutrients in isolation from one another.
The overall time it takes to completely digest food is about:
- 2.5 to 3 hours for stomach contents to empty 50%
- 4 to 5 hours for the stomach to empty completely
- 2.5 to 3 hours for the small intestine to empty 50%
- 30 to 40 hours for transit time through the colon15
Tips For Better Digestion
Having healthy digestion involves more than just the type of food you eat and how you eat it. But what you eat does go a long way. There are ways to support your digestion and potentially avoid having digestive issues such as gas, constipation, and diarrhea, which afflict as many as 15% of people in Western countries.16
Eat More Whole Grains, Greens, And Fruits
Unlike refined carbohydrates, like white bread and pasta, whole grains are loaded with tons of fiber and nutrients, such as omega-3 fatty acids. These whole grains are fermented by healthy gut bacteria in the small intestine, which results in the production of short-chain fatty acids. These molecules are important because they contribute to proper functioning of the cells lining the colon.17
Additionally, eating high-fiber foods contributes to optimal colon function. Leafy greens, such as spinach or kale, are high in fiber content, not to mention other essential nutrients, like vitamins A, C, and K.18 They’re also a good source of an unusual sugar called sulfoquinovose or SQ, which enables beneficial bacteria to grow and thrive in the gut.19
Finally, certain fruits, like apples, pears, and mangos, contain high amounts of fructose. The fructose leads to gas and intestinal discomfort as it ferments.20 Swapping those fruits for berries, oranges, grapefruit, and bananas may help ease the gas and stimulate growth of healthy bacteria in the gut.21
Eat Less Red Meat And Processed Foods
Processed foods can save time, but you need to evaluate their nutritional content and long-term health effects.22 They often contain huge amounts of sugar, salt, and additives, with almost no fiber. These ingredients may negatively impact digestion. Ditching processed foods may help support a better digestive process.23
The issue with red meat is that it takes 8-12 hours to process. This is at least two hours more than the digestion times an average meal takes to process. Reducing red meat intake may help support gut health.24
Include Probiotics In Your Diet
Gut health is an integral part of maintaining good digestive health. Introducing beneficial bacteria into your diet via probiotic foods, such as yogurt, kimchi, and sauerkraut, may have a protective effect on the digestive system. Having the right balance of bacteria may help keep harmful microorganisms from multiplying, supporting healthy digestion, and helping with nutrient absorption.25
Drink Lots Of Water
Drinking around 8 glasses of water a day is essential for the body to function properly. When it comes to optimal digestive health, the best time to drink a glass of water is about 30 minutes prior to a meal. On the other end of the meal, drinking a glass about an hour after finishing the meal will help the body absorb the nutrients in your food as the digestive process is underway. On the other hand, drinking too much water during the meal itself may dilute your digestive juices.26
Managing The Digestive Process
The answer to the question, “how long does it take to digest food?” is nuanced. Digestion of food is a complex process that may take days to complete. Fortunately, there are many factors involved that are well within your control to influence digestion times. They include consuming foods that contain as many essential nutrients as possible, eating high fiber foods, avoiding processed foods wherever possible, drinking plenty of water, and moving your body around.