How to Improve Stool Consistency: A Guide to Healthier Bowel Movements

Are your stools often too hard, too loose, difficult to pass or constantly changing?

Stool consistency can be a useful window into what is happening within your digestive system. While everyone's bowel habits are slightly different, consistently hard, loose or unpredictable stools may indicate that something in your diet, lifestyle or digestive health needs attention. The good news is that there are several simple strategies that can help you achieve more regular, well-formed bowel movements.

What is a healthy stool consistency?

One of the easiest ways to assess stool consistency is the Bristol Stool Form Scale. It categorises stools from Type 1 through to Type 7, ranging from hard, separate lumps to completely watery stools. It is widely used in clinical practice and research to describe bowel movements consistently. [1,2]

Generally:

• Types 1–2: hard, lumpy stools, commonly associated with constipation

• Types 3–4: formed stools that are generally considered the ideal range

• Type 5: soft blobs that may indicate faster transit

• Types 6–7: loose or watery stools, commonly associated with diarrhoea

Type 4 - a smooth, soft, sausage shaped stool, is often used as a practical target when managing bowel symptoms, although what is normal can vary between individuals. [2,3]

Why does stool consistency change?

Your stool is made up of water, bacteria, undigested food particles, fibre and other substances. How quickly food moves through your digestive tract influences how much water is absorbed. When transit is slower, more water can be absorbed from the stool, potentially resulting in harder stools. When transit is faster, less water is absorbed, which can result in softer or watery stools. [2]

This means that stool consistency can be influenced by a number of factors, including:

• Fibre intake

• Fluid intake

• Dietary changes

• Stress

• Physical activity

• Changes in gut bacteria

• Medications and supplements

• Food intolerances or sensitivities

• IBS and other digestive conditions

• Changes in gut motility

Rather than simply trying to "fix" your stool, it can therefore be helpful to consider why your bowel movements are changing in the first place.

1. Get the right type of fibre

Fibre is one of the most important dietary factors when it comes to stool consistency – but more fibre isn't always better. There are different types of fibre, and they can affect the digestive system in different ways. Soluble, viscous fibre can absorb water and form a gel-like substance within the digestive tract. This can help add bulk and improve stool consistency, making it particularly useful when stools are either too loose or too hard. Psyllium husk is one example of a fibre that has been studied for this purpose. Recent research has found benefits from fibre supplementation in IBS, with psyllium showing particularly promising results. [4]

Other sources of soluble fibre include:

• Oats

• Chia seeds

• Ground flaxseeds

• Kiwi

• Psyllium husk

• Carrots

• Sweet potato

• Aubergine

• Citrus fruits

If you currently eat very little fibre, increase it gradually rather than suddenly adding large amounts. A rapid increase can cause bloating, gas and abdominal discomfort.

2. Don't forget your fluids

Fibre and fluid work together. If you're increasing your fibre intake while drinking very little, you may find that your stools become harder rather than easier to pass. Aim to drink regularly throughout the day, with water making up the majority of your fluid intake. Your individual requirements will vary depending on factors such as body size, activity levels, climate and diet. If you are experiencing diarrhoea, maintaining adequate fluid intake becomes particularly important because you may be losing additional water and electrolytes.

3. Eat a variety of plant foods

A diverse diet provides different types of fibre and other compounds that interact with the gut microbiome. Rather than relying on one food or one "superfood", aim to gradually increase the variety of plant foods you eat.

Try incorporating:

• Different vegetables

• Fruits

• Wholegrains

• Nuts and seeds

• Beans and lentils, where tolerated

If you have IBS or a sensitive digestive system, suddenly increasing plant foods may worsen bloating and gas. In this situation, the goal is gradual, individualised change, rather than trying to eat huge quantities of fibre overnight.

4. If your stools are loose, look at your diet

If you're regularly experiencing Type 6 or 7 stools, it is worth looking at what may be contributing.

For some people, loose stools may be aggravated by:

• Large amounts of caffeine

• Alcohol

• Very fatty meals

• Sugar alcohols such as sorbitol

• Large amounts of certain fermentable carbohydrates

• Sudden increases in fibre

• Certain medications or supplements

Keeping a short food and symptom diary can help identify patterns.

However, it's important not to start eliminating lots of foods without a clear reason. Restrictive diets can make it harder to meet your nutritional requirements and may unnecessarily reduce dietary variety.

5. If your stools are hard, don't simply add more bran

Constipation isn't always caused by eating too little fibre. Hard stools can be associated with inadequate fluid intake, slow gut transit, low physical activity, changes in routine and other digestive or medical factors. Some people find that increasing insoluble fibre, such as large amounts of bran, actually makes bloating and discomfort worse. Instead, consider introducing gentler sources of soluble and viscous fibre, increasing fluids and gradually increasing overall dietary fibre according to your tolerance. Research supports the use of fibre for constipation, with psyllium showing evidence for improving stool frequency and consistency. [5]

6. Keep meals regular

Your digestive system responds to eating. Having relatively regular meals can help establish a predictable routine for your digestive system and bowel movements. Rather than constantly grazing throughout the day, try establishing a consistent pattern of meals that works for you.

For example:

Breakfast → lunch → dinner

You can then add snacks if you genuinely need them. Your bowel doesn't necessarily need to move at exactly the same time every day, but establishing a consistent routine can make bowel habits easier to manage.

7. Don't ignore the urge to go

If you regularly ignore the urge to have a bowel movement, your body can become less responsive to those signals. When you feel the urge, try to give yourself enough time to use the toilet rather than repeatedly delaying it. Your toilet position can also make a difference. Placing your feet on a small footstool can raise your knees above your hips and create a more natural squatting position, which may make passing stool easier.

8. Move your body

Physical activity can support healthy bowel function. You don't need to spend hours exercising. Regular walking, strength training and general movement throughout the day can all contribute to a healthy lifestyle and may be particularly helpful if constipation is an issue. If you sit for long periods, try incorporating short movement breaks throughout the day.

9. Consider your stress levels

Your digestive system and nervous system are closely connected through the gut-brain axis. Stress can influence gut motility and digestive symptoms, and some people notice that their bowel habits change significantly during periods of stress. If you notice that your stools become looser before an important meeting, during periods of anxiety or when you're particularly stressed, this may be an important part of the picture. Supporting your nervous system alongside your diet can therefore be just as important as focusing on food.

Simple strategies include:

• Regular exercise

• Time outdoors

• Breathing exercises

• Relaxation techniques

• Consistent sleep

• Taking time to eat meals without rushing

10. Look beyond stool consistency

If your stools are consistently abnormal, changing your diet isn't necessarily the whole answer. Persistent changes in bowel habits can occur alongside conditions such as IBS, coeliac disease, inflammatory bowel disease, infections, bile acid diarrhoea and other digestive disorders. Other symptoms are important too.

Pay attention to whether you also experience:

• Persistent bloating

• Abdominal pain

• Excessive gas

• Urgency

• Feeling that you haven't completely emptied your bowel

• Mucus

• Reflux or indigestion

• Unexplained weight loss

• Fatigue

• Blood in your stool

If bowel changes are persistent, severe or accompanied by concerning symptoms, speak to your GP or another appropriately qualified healthcare professional.

What should you aim for?

Rather than obsessing over having a bowel movement every day, consider looking at the overall pattern. A healthy bowel pattern generally means stools that are:

Formed + soft + easy to pass + relatively consistent for you.

The Bristol Stool Form Scale can be a useful tool for tracking changes over time, particularly if you're working with a healthcare professional. [1,2]

A simple starting point

If your stools are inconsistent, don't try to change everything at once.

Start with these five habits:

1. Eat regular, balanced meals.

2. Gradually increase fibre, focusing on a variety of plant foods.

3. Drink enough fluids throughout the day.

4. Move your body regularly.

5. Track your stool consistency alongside symptoms, food and lifestyle factors.

This can help you identify patterns rather than simply reacting to each bowel movement.

The bottom line

There isn't one food or supplement that will magically create the perfect stool. Improving stool consistency is usually about looking at the bigger picture - fibre, fluids, food choices, meal patterns, movement, stress, gut motility and underlying digestive health. If you regularly experience constipation, diarrhoea or alternating bowel habits, it can be worth investigating the underlying cause rather than simply trying to manage the stool itself. At Kiwi Nutrition, I help clients understand their digestive symptoms and develop personalised nutrition strategies to support better gut health and more comfortable digestion.

If you're struggling with bloating, IBS, constipation, diarrhoea or unpredictable bowel movements, book a discovery callto discuss how nutritional therapy could support you.

References

1. Riegler G, Esposito I. Bristol scale stool form. A still valid help in medical practice and clinical research. Tech Coloproctol. 2001;5:163–164.

2. O'Donnell LJD, et al. Stool form scale as a useful guide to intestinal transit time. Scand J Gastroenterol. 1997;32:920–924.

3. Lewis SJ, Heaton KW. The Bristol Stool Form Scale and its relationship with stool consistency and intestinal transit.

4. Fiber supplementation in irritable bowel syndrome: a systematic review and meta-analysis of randomized controlled trials. 2026.

5. Suares NC, Ford AC. Effect of fiber supplementation on chronic constipation in adults: an updated systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2022.