How Long Does It Take To Digest Food?

how long does digestion take

Food is an important part of our lives as it provides us with the much-needed energy and nutrients necessary for the activities of daily living.

However, for food to yield energy, it has to be digested. Different types of food are digested in different ways leading to differing lengths of time required for digestion.

This article describes the digestive process and the time it takes for these various classes of foods to be digested.

How Long Does It Take For Food To Be Digested?

food table

After reaching the stomach, food may spend up to four hours in the small intestine, undergoing absorption. It then spends from 6 to 60 hours in the small and large intestines.

The different food classes take varying amounts of time to get through the whole process of digestion, from as little as 24 hours to as long as 3 days. This process is variable and depends on:

  1. The food type: Generally, refined sugars and fruits are easily digested when compared to fatty foods.
  2. Age: Digestion is much faster in children than in adults due to their need for nutrients necessary for growth and development as well as their increased rates of metabolism. As you age, digestion, like most body processes, becomes progressively slower.
  3. Gender: It is thought that digestion is slower in women than in men. This is due to the effects of hormones on the process of digestion.
  4. Metabolism: Individuals with a higher basal metabolic rate digest food faster than those with a low or normal metabolism. This includes athletes and people in harsh weather conditions.
  5. The health of the individual: This is the overall health of the individual, as well as the health of each part of the digestive system. Generally, healthy people utilize and process food much faster than ill people. Also, a disease affecting one part of the tract often slows down the process of digestion.

Eating healthy, exercising and drinking water aids the process of digestion. Sometimes, the transit time of food in the gut speeds up, as is the case in diarrhea. Here the body tries to rid itself of an invader in the digestive system.

Sometimes, the process is somewhat halted, as in the case of constipation which may be precipitated by diseases of the digestive system, medicines or stress.

What Are The Classes Of Food?

food classes

There are 7 classes of food. However, 5 main food classes (also called macronutrients) recur in our everyday meals. These are:

  1. Carbohydrates: The starch or sugar containing food items which give us energy, such as rice, potatoes, and bread.
  2. Protein: The building blocks of the body, they replenish lost cells and help us repair our bodies such as beans, eggs, and fish.
  3. Fat and Oils: These oily food items are important for providing necessary energy, vitamin, and minerals. They include palm oil and vegetable oil.
  4. Water
  5. Fiber: These are carbohydrates that our bodies cannot digest because we don’t have the enzymes to do so. they form the majority of our stool. They are found in fruits, vegetables, and cereals.
  6. Vitamins
  7. Minerals

The other 2 food classes are referred to as micronutrients because they occur in minimal quantities in our foods and our bodies require only a little of these nutrients to function optimally.

 

Are Food Items Digested The Same Way?

food combination

The processes for different food classes differ, varying from class to class. Chemical messengers (or hormones) work on separate parts of the digestive system to keep things in order while enzymes breakdown the food into smaller bits.

For carbohydrates and starchy food items, digestion begins in the mouth with the enzyme, salivary amylase immediately swinging into action to break down carbohydrate from complex sugars to less complex ones. This prepares them for further breakdown in the stomach by other enzymes.

Fatty foods are first acted on in the mouth by an enzyme called lingual lipase which breaks them down into small fractions, however, they are mostly digested in the small intestine with the aid of pancreatic enzymes.

Proteins on their part are mostly digested in the stomach and small intestine. Water doesn’t need to be broken down because it already comes in the perfect form for absorption by our gut.

How Is Food Digested?

the digestive tract

You may have wondered how your body utilizes all the food you take in, converting it into various forms:

  • As energy for your day to day activities,
  • Nutrients for growth and replenishment of body cells.

When we eat food such as bread or cucumbers, they are not in suitable forms for the body’s immediate use. Therefore, it needs to be transformed into usable forms.  The process of converting food items into useful forms that provide the body nourishment is the term digestion.

Digestion is a vital process necessary for good health and well-being. It occurs in the aptly termed digestive system, a series of hollow interconnected organs starting from the mouth and ending in the anus.

The digestive system is a collection of organs and glands that produce chemicals. Food is broken down from large food molecules into small parts mechanically (by chewing), and via the aid of chemicals (enzymes).

This system transforms food and drinks into fractions small enough to enter cells all over the body. These cells use nutrients from food for energy needs and nourishment.

Where It All Begins- Your Mouth

salivation

Typically, the smell and sight of food cause you to salivate, that is, to produce more saliva in your mouth than prior to the introduction of food. This is the start of the process of digestion.

When food is taken into the mouth and chewed, it mixes up with saliva which contains enzymes responsible for breaking down food so that swallowing is a lot easier.

At the end of the process of chewing, the tongue helps nudge the now round, ball-like food called bolus in the direction of the esophagus, the second part of the digestive system.

The Esophagus And Stomach

stomach acid

The esophagus is a long tube-like organ that connects the mouth to the stomach. In the walls of the esophagus contain different muscle fibers which further help to squeeze the food down to the stomach, through a ring-like constriction or valve formed by muscle fibers.

This acts as a shutter between the esophagus and stomach, preventing food from returning to the esophagus once it has reached the stomach.

The stomach has different parts and is responsible for ensuring that food is properly broken down by first storing food and then ensuring that food is adequately mixed with gastric juices.

These chemicals further break down food before pushing it through the narrow end of the stomach leading up to the small intestine.

The Small Intestine

how long does digetion take

The small intestine starts at the end of the stomach and is a long narrow tube with several coils mainly responsible for the absorption of food. When stretched out, it may be as long as 22 feet.

It has four distinct parts, all carrying out separate functions, with their muscle walls able to help propel food throughout the length of the small intestine.

The gall bladder, pancreas, and liver secrete special digestive chemicals or juices which are released into the small intestine. These chemicals help in further breaking down food particles into near microscopic sizes. They also help absorb important vitamins and minerals.

Embedded in the small intestine are finger-like projections called villi which are connected to blood vessels, allowing the broken-down food, now a watery, thin, absorbable mixture, to enter into the bloodstream on the road to the liver for further processing.

For undigested food and dead cells from the digestive tract, their journey continues to the large intestine, a shorter but wider tube compared to the small intestine.

The Large Intestine: End Of The Road

The main process carried out in the large intestine is the extraction of water from the liquid undigested food passed from the small intestine.

This usually lasts for over a day, making food harder than it was in the small intestine. the remnant is what is eventually passed out as our poop.

In Summary

Learning about the long and tedious process of digestion shows us that the process takes a pretty long time, from as ‘little’ as 24 hours to as long as 3 days.

This process is necessary to nourish the body in order to live healthy and strong.

Dr. Zubair Abdulahi

Dr. Zubair Abdulahi

Dr. Zubair Abdulahi is a licensed medical practitioner with a degree in medicine and surgery who is interested in using new media to influence health decisions by providing information on health queries. When he's not working as a doctor, he enjoys the game of football as well as sight-seeing and listening to classical music.
Dr. Zubair Abdulahi

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