Constipation diet: what to eat when you’re struggling to go

If you’re constipated, one of the first things you might be told is to eat more fibre. And whilst that is something to be aware of, constipation isn’t always that simple. If it was you probably wouldn’t be reading this!

For some people, increasing fibre really does help (and in this post I’ll share HOW to do that). For others, eating a very high fibre diet can make things worse, particularly if you’re already bloated, uncomfortable or struggling to get things moving.

So what should you actually eat if you’re constipated?

The answer depends on what’s happening in your digestive system, but there are some useful principles to think about when you’re looking at your diet for constipation.

What is the best diet for constipation?

There isn’t one perfect constipation diet that works for everyone. Two approaches you could consider are:

• eating more fibre
• following a low FODMAP diet

When I work with my IBS clients I will consider both options, as both can be useful in the right circumstances, but each person responds differently.

If you’re already very constipated, bloated and uncomfortable, adding lots more fibre at the start isn’t necessarily going to make you feel better. Equally, if you’re following a very restrictive low FODMAP diet and barely eating any fruit or vegetables, you may not be getting enough fibre or variety.

Should you eat more fibre if you’re constipated?

Fibre is important for bowel health, as well as cardiovascular health, weight maintenance, and even brain health! We know that increasing fibre can help some people with constipation.

But the term fibre covers a lot of different types of foods, with different properties, and they behave differently in your digestive system. Fibre can be split into three main sliding scales:

• Soluble / Insoluble – how much they dissolve in water
• Gel forming – how much of a gel they form in your gut
• Fermentability – how much prebiotic fibre they provide for your gut microbes (and how rapidly this fibre ferments)

Most plant based foods have some element of each of these properties. So when we’re talking about fibre and constipation, it’s not fibremaxxing we’re going for (getting the biggest possible number of grams every day). The type of fibre matters too.

Insoluble fibre

Insoluble fibre doesn’t dissolve in water and can add bulk to your stool. This type of fibre can stimulate the need to have a bowel movement because there is more bulk for the intestines to move through.

You’ll find it in foods such as wheatbran (e.g. Branflakes, All Bran), some vegetables, fruit skins, nuts and seeds.

Soluble and gel-forming fibre

Other fibres dissolve in water and can form a gel. This helps to form a soft but ‘held together’ poo.

A good example is chia seeds. Leave chia seeds in water and they become gelatinous and sticky because they absorb water. Oats also contain soluble, gel-forming fibre and can help form a bowel movement that is soft but still formed.

Fermentable fibre

Some foods are rapidly fermentable by your gut microbes and this is what causes the excessive bloating in IBS. These foods are sometimes called prebiotics. Examples would be onions, garlic, wheat, beans and pulses, artichoke, asparagus, apples. These are all high FODMAP foods.

Side note: (It’s also worth knowing that some gas production is normal, and even desirable because it means the good bacteria are doing what they should!) but some people with IBS have visceral hypersensitivity which means they feel a lot of pain at small levels of gas production.

Can too much fibre make constipation worse?

Yes, sometimes. If you’ve been trying really hard to eat a healthy diet, you might already be eating brown rice, wholegrain bread, several portions of vegetables, fruit, seeds and other high-fibre foods every day.

And those foods can absolutely be part of a healthy diet. However, if you have a lot of methane-producing microbes, eating large amounts of certain types of fibre can increase gas production which causes more bloating or pain.

If you have pelvic floor dysfunction, hypermobility disorders, adhesions, a stricture or another problem affecting the physical passage through your intestines, adding more fibre doesn’t necessarily make things move faster.

Sometimes reducing the most fermentable fibres temporarily can ease the pressure by reducing gas production. This can be helpful when it is combined with something that helps the bowel move like a laxative.

The aim isn’t necessarily to stay on a low-fibre diet forever. But if you can get things moving you can then work to build your diet back up again.

What should you eat if you’re constipated?

If you aren’t following a particularly restrictive diet, I’d generally be looking at variety rather than simply trying to cram in as much fibre as possible.

Fruit and vegetables are a good place to start. They provide different types of fibre as well as vitamins, minerals and other plant compounds that your body needs.

For someone with IBS-C, this might mean gradually increasing your intake rather than suddenly adding huge amounts of fibre overnight.

If you’re currently eating very little variety because you feel that everything causes symptoms, the first step may simply be to find a few more foods you can tolerate.

What if you’re following a low FODMAP diet?

The low FODMAP diet can reduce bloating, gas and abdominal discomfort for some people. It can also take some of the pressure off if you feel as though everything is fermenting and building up in your gut.

But a low FODMAP diet can also reduce your intake of fibre unless you’re being careful about it.

Some of the foods restricted on a low FODMAP diet contain carbohydrates called polyols, including sorbitol and mannitol. These foods (such as mushrooms, celery, peaches or cherries) can draw water into the bowel, which may help keep stools softer for some people with constipation.

So a strict low FODMAP diet could remove some of these foods which help retain a bit of water in the bowel. If you’re already following low FODMAP and you’re constipated, one of the first things I’d look at is:

How can we increase your fibre and food variety while keeping your symptoms manageable?

Low FODMAP foods that can help you increase variety

There are more low FODMAP fruit and vegetables available than many people realise. Did you know these examples of low FODMAP portions? Check out:

• mange tout
• sweetcorn
• aubergine
• broccoli
• cauliflower
• pineapple
• papaya
• kiwi
• raspberries
• spinach
• green beans

The FODMAP diet is all about portion sizing so use a reliable resource such as the Monash FODMAP app when checking individual foods.

The aim is to find opportunities to add more variety to your meals, which can help add different types of fibre. You’ll also be getting a wider variety of vitamins and minerals that support the systems involved in digestion and gut movement like your nervous system and immune system.

How much fibre should you eat for constipation?

As a general starting point, I often suggest aiming for around 25 to 30g of fibre per day, depending on your body size and how much you’re eating.

If you’re currently eating very little fibre, suddenly jumping to 30g can make things worse because you need to adjust your hydration levels, and allow your digestion time to get used to more volume coming through. Start by just adding one portion of fruit or veg per day, and build up slowly.

If you’re already eating a very high fibre diet yet still constipated, eating even more may not be helpful. You may need a different balance of fermentable, soluble and gel forming (those three types of fibre). This might even include reducing some types of fibre while you work on getting things moving.

What about laxatives and a constipation diet?

Laxatives can be an important part of managing constipation, particularly when you’re very backed up. For many of my clients there is some reluctance around using them. Maybe you feel:

“I don’t want to rely on laxatives.”

Or:

“I want to fix my constipation naturally through food.”

I completely understand that. But if you’re only going to the toilet once a week and you’re extremely bloated, uncomfortable and in pain, it can be very difficult to make dietary changes.

Almost everything you eat can feel as though it causes a reaction when it joins a gut that is already full. Sometimes getting things moving first makes it much easier to make changes to your diet in the long run. This is where starting to use laxatives can be a helpful tool.

If you think you need laxatives, speak to your GP or pharmacist about which type is most appropriate for you.

What if eating makes your constipation worse?

This is another reason constipation diets can be confusing. You might eat something and then feel bloated, painful and uncomfortable. It’s very easy to conclude:

“That food has caused my symptoms.”

But the food you’ve just eaten isn’t necessarily the thing causing the pain. Eating activates your whole digestive system – your stomach starts working, your small intestines start moving because the gastrocolic reflex encourages the bowel to make room for new food coming in.

If your intestines are already stretched and full of hard stool, that movement can be really painful. Plus, if you’ve got gas production then bubbles of air are also trying to squeeze through this very tight space.

So if eating seems to trigger your symptoms, it doesn’t automatically mean that you need to stop eating whatever was in that last meal. Especially if food has been sitting in your digestion for a few days.

What if you’re only eating a few ‘safe’ foods?

For some people with IBS and constipation it makes sense to reduce food variety because everything seems to make things worse. Maybe you’ve ended up eating ten foods or fewer because you don’t trust what happens when you do eat.

When every meal seems to result in bloating, pain or discomfort, eating less can feel safer. But a very restricted diet makes it much harder to get enough variety, fibre and nutrients. There is also an issue with undereating and a lack of volume actually causing constipation and slow transit.

So rather than asking “What else can I remove?”, with my client’s I’m often working through “What could we add?”

That might mean trying one new fruit or vegetable at a time, using low FODMAP portions if appropriate, or experimenting with different types of fibre.

Your constipation diet doesn’t need to be perfect

There are a lot of misconceptions around IBS diets. You can end up feeling as though you need to control everything:

No alcohol.

No sugar.

No dairy / gluten

No mistakes.

That isn’t a realistic way to eat long term, and it takes away a lot of the joy in food. Your diet needs to be good enough, like the 80/20 rule.

A simple way to look at your constipation diet

If you want to start working out whether your diet could be contributing to your constipation, don’t change everything at once.

For 4-7 days, you could track:

• how many portions of fruit and vegetables you’re eating
• roughly how much fibre you’re getting
• how often you’re opening your bowels
• what your stools are like
• your bloating and abdominal discomfort

A portion of fruit or vegetables is around 80g, or roughly a handful of chopped vegetables, three florets of broccoli, an apple or a banana.

You could use an app such as Cronometer or MyFitnessPal to get an idea of your fibre intake.

But I wouldn’t recommend tracking your food forever. A short period can give you useful information, but long-term food tracking can become obsessive.

The point is to gather some information, and look and what data you bring out.

So, what is the best diet for constipation?

The best constipation diet isn’t necessarily the one with the most fibre. And it isn’t necessarily a low FODMAP diet either.

Your ‘best diet’ depends on what you’re eating now, how restricted your diet has become, how your digestive system is behaving and what happens when you change different types of fibre.

For some people, increasing fibre and food variety can help.

For others, reducing certain types of fibre can ease pressure while they work on getting things moving.

If you’re following a low FODMAP diet, you may need to find ways to increase your fibre and fruit and vegetable intake without making your IBS symptoms worse. The aim is to find an approach that helps you eat enough, get enough variety and support your bowel movements without creating another restrictive diet.

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