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Woman eating spaghetti, good digestion

Digestion: The only overview you need

23 May 2023 • 21 min read


From feeling butterflies to stomach ache, your digestive system has a big impact on your wider wellbeing. Understanding how it works is the first step to staying well.

From the boom in friendly bacteria supplements to ‘free from’ supermarket aisles, we’re increasingly interested in our digestive wellness.

And no wonder – 40% of us have at least one digestive issue, such as indigestion, at any one time.1

Yet, how many of us really know what’s going on in the full nine metres of our digestive tract.2

It’s time to find out!

What is the digestive system?

Although we eat food, our digestive system doesn’t absorb food – it absorbs nutrients.

So, our food has to be broken down into amino acids from proteins, fatty acids from various fats, and simple sugars from carbohydrates, as well as vitamins, minerals and other essential nutrients.

Your digestion is a complex network of organs that manages this process, breaking down food into different compounds, and passing out what we don’t need as waste.

The whole process takes on average one to three days.3

Digestion times also massively depend on whether you are eating solids or liquids, with soups and juices taking less time to process than hard foods.

Regardless of what you eat and in what form, everything you consume makes its way from your mouth and into your bloodstream or rectum via the same route (more on this below).

The part of the digestive tract known as the gut also contains trillions of various microorganisms, or beneficial bacteria, many of which help support our immune system4.

Plus, it has over 100,000 nerve cells and is closely linked to our emotions, which is why we tend to get butterflies or diarrhoea when we’re feeling nervous or stressed.5

Why is digestive health so important?

The digestive system takes the food that we eat and breaks it down into nutrients.

Once the nutrients are small enough, they can be absorbed by the body into the bloodstream.

Keeping the digestive system healthy makes sure the process is efficient and that we get the most from our food as possible.

However, digestive health also influences the health of other physiological systems in the body.

healthy gut can also lead to a healthy immune system, heart and brain, as well as good quality sleep and maintenance of a healthy weight.



  • Our digestive system is a complex network of organs that breaks food down into different compounds and passes out what we don’t need as waste
  • On average, this process takes one to three days
  • Keeping the digestive system healthy makes sure the process is efficient and that we get the most from our food as possible

How does the digestive system work?

Let’s take a close look at your digestion, from start to finish – quite literally.

The mouth


The oesophagus


The stomach


The small intestine


The liver, gallbladder and pancreas


The large intestine


How long does it take to digest food?

The time it takes for food to move through the full gastrointestinal tract (GI) depends on the type and amount of food eaten.

Generally speaking, it takes 6 to 8 hours for food to pass through both the stomach and the small intestine before reaching the large intestine.

Once it’s in the large intestine or colon, it remains there for between 10 and 59 hours while it’s broken down further.

The whole process takes anything between 10 hours and 3 days.

What foods are hardest to digest?

According to our in-house nutritionists, food that’s more complex in structure is generally more difficult and takes the body longer to digest.

For example, protein, some processed foods, and high fat foods, tend to take the longest to digest because the process doesn’t begin until they reach the small intestine.

Meanwhile, other food may not be difficult for the body to digest but can potentially impact digestive health through irritation and inflammation of the GI tract. This includes food with high acidity levels, spicy foods, caffeine, artificial sweeteners and alcohol.

Foods high in fibre take longer to digest as they aren't fully broken down until they reach the large intestine. This can be beneficial for gut health.25

Can food stay in your stomach for days?

Food should only take 2 to 4 hours to move out of the stomach.

However, as we’ve just mentioned above, depending on what you’ve eaten, it can remain in the large intestine for anything between 10 hours and 3 days.


  • The time it takes for food to move through the gastrointestinal tract depends on what’s been eaten and the amount
  • High fat food tends to take the longest to digest
  • Food can sit around in the large intestine from anywhere between 10 hours and 3 days

Lifestyle tips for better digestion

Is there anything you can do to improve your digestion? Most definitely! Here are 5 ways to get started:

  1. Minimise stress - stress is one the major lifestyle factors that impacts digestive health. Higher stress levels reduce the diversity of the gut bacteria and increase the risk of digestive disorders. Where possible, take regular breaks, spend time outside, establish a good work-life balance and explore aromatherapy and breathing techniques.
  2. Sleep well - sleep quality and gut health are connected. Sleep deprivation can lead to changes in the gut microbiota, affecting digestive health.
  3. Exercise regularly – exercising helps enrich the diversity of bacteria in the gut and reduces the risk of putting on weight, which can cause digestive disorders.
  4. Reduce your alcohol intake – alcohol causes inflammation in the gut and can have an adverse effect on your health and wellbeing.
  5. Drink plenty of water - staying hydrated helps to regulate bowel movements. Speaking of bowel movements…..

How many times a day should you poop?

We put this question to our nutritionists, and they told us there’s no generally accepted number of times a person should poop.

Anything between 3 times per day to 3 times a week is considered healthy.

However, anything more or less than this (constipation or diarrhoea) is potentially a sign of an unhealthy gut.


  • There are several lifestyle changes you can make to improve your digestive health. They include: sleeping well, reducing stress and upping your water intake
  • The frequency of your bowel movements is determined by how your body functions
  • Constipation and diarrhoea are both signs of poor gut health

When to see your GP

See your doctor if any of the symptoms above continue for longer than is normal for you.

If you also experience loss of appetite, black or bloody stools, or unexplained weight loss, make an appointment straight away.26

A final few words about the digestive system

The power of the digestive system isn’t to be underestimated, yet most of us can be guilty of overlooking it and not giving it the TLC it needs from time-to-time.

The first step towards achieving good digestive health is recognising the important role it plays in our body, from extracting nutrients from food to determining how regular our bowel movements are.

We hope you’ve found this overview useful, and that it inspires you to think about your digestive system that little bit more and tune into what it’s telling you about your body.

You’ll be surprised at how easy keeping tabs on your digestive health can be, especially when there are so many digestive health tablets and supplements available to help boost your system.

Make today the day you start paying closer attention to your digestive system, you’ll be pleasantly surprised by the widespread benefits it may provide you with!

Understanding the importance of a healthy gut

Ever suffer with bloating or discomfort but don't know why? Despite having 100% the same DNA Lisa and Alana Macfarlane (The Mac Twins) only have 30-40% of the same microbiota, in this episode we look at:

  • Why gut health is so important?
  • How your gut health impacts more than just your digestion
  • Ways to fit wellness into your day





Author: Ro HuntrissRegistered Dietitian

MRes Clinical Research - University of Manchester, 2016

Ro Huntriss is a UK-based Registered Dietitian. Ro has over 10 years of experience working as a dietitian and has worked across many different sectors including NHS, private practice, research, digital health, health technologies and supporting commercial businesses.

Ro is a specialist in a variety of areas to include weight management, diabetes, women’s health, gastrointestinal and cardiovascular health. Ro expanded her expertise to a number of areas as she believes that health is not one dimensional and health should be considered from several angles. 

In her spare time, Ro enjoys yoga and netball, playing the piano and is an avid Tottenham Hotspur fan! 



Professional Accomplishments

  • Community Nutrition Professional of the Year 2021 - CN Magazines 

Affiliations/Memberships/Governing bodies


  • Kumar, K.D., Huntriss, R., Green, E., Bora, S. and Pettitt, C. (2022). Development of a nutrition screening tool to identify need for dietetic intervention in female infertility. Journal of Human Nutrition and Dietetics, doi: 10.1111/jhn.13055.
  • Huntriss, R., Haines, M., Jones, L. and Mulligan, D. (2021). A service evaluation exploring the effectiveness of a locally commissioned tier 3 weight management programme offering face-to-face, telephone and digital dietetic support. Clinical Obesity, e12444. 
  • Huntriss, R., Boocock, R. and McArdle, P. (2019). Dietary carbohydrate restriction as a management strategy for adults with type 2 diabetes: Exploring the opinions of dietitians. Journal of Diabetes Nursing, 23: JDN104. 
  • Huntriss, R., Campbell, M., and Bedwell, C. (2018). The interpretation and effect of a low-carbohydrate diet in the management of type 2 diabetes: a systematic review and meta-analysis of randomised controlled trials. European journal of clinical nutrition, 72(3), pp. 311–325.
  • Huntriss, R. and White, H. (2016). Evaluation of a 12-week weight management group for people with type 2 diabetes and pre-diabetes in a multi-ethnic population. Journal of Diabetes Nursing, 20, pp. 65-71. 
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