Short answer. A low-residue diet (called diet No. 5, the residue-restricted diet, in Czech hospitals) is a way of eating with as little fibre as possible. You can eat white bread, pasta, white rice, peeled potatoes, lean meat, fish, yoghurt, cooked root vegetables and ripe bananas. Wholemeal bread, pulses, nuts, seeds, and raw fruit and vegetables with skins or seeds are left out.
Before a colonoscopy, the diet is followed for three to seven days depending on the clinic, and on the day before you only have a light breakfast, followed by clear broth and fluids. The exact procedure is always set by your doctor or the clinic carrying out the examination.
The world is full of diets. Some are recommended by doctors, others by magazines. One is meant to help you lose weight, another to give you energy. One more of these is the low-residue diet. What does it involve, what are its benefits and who should actually follow it? Read on to find out whether this diet is right for you.
Table of contents
What is a low-residue diet?
If your doctor tells you that you have inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis, they may recommend a low-residue diet. The basic idea is that you eat foods that are easy to digest and cut down on those that are not.
This means limiting high-fibre foods such as wholemeal bread and cereals, nuts, seeds, and raw or dried fruit and vegetables.
In this diet, “residue” means the undigested parts of food, including fibre, that form stools. The aim of the diet is for you to have fewer and smaller stools each day. This eases symptoms such as diarrhoea, bloating, wind and stomach cramps.
Residue-free, low-residue and diet No. 5
It is impossible to eat with no residue at all, as stools form even from easily digestible food. Hospitals therefore use the more accurate term residue-restricted diet. In the Czech therapeutic diet system it is number 5, and the General University Hospital in Prague (Všeobecná fakultní nemocnice v Praze, VFN) describes it in its patient material as a complete, easily digestible diet without foods that cause wind, hard crusts, skins or seeds.
In practice, a low-residue diet and a residue-free diet mean the same thing. In a 2015 review in the journal Advances in Nutrition, the authors Vanhauwaert, Matthys, Verdonck and De Preter pointed out that the Academy of Nutrition and Dietetics in the US removed the term low-residue diet from its clinical nutrition manual. This is because there is no scientific definition of “residue” and no way of measuring it. The authors suggested speaking instead of a low-fibre diet, with no more than 10 grams of fibre a day.
The food lists in this article are based on American recommendations for a low-fibre diet, and Czech hospitals tend to be stricter. VFN does not include mushrooms, mayonnaise, ketchup, soy sauce, ground coffee or chocolate in diet No. 5. Na Homolce Hospital (Nemocnice Na Homolce) does not serve milk as a drink on its own in diet 5a for diarrhoea. Where the lists differ, follow the instructions of your doctor or clinical dietitian.
Who a low-residue diet is suitable for
As with many other nutrition trends or even long-established diets, such as the Dukan diet from the 1970s, the answer to the question “is a low-residue diet healthy?” is “it depends”. For a healthy person it is usually neither healthy nor necessary.
However, it can be very beneficial if it is suggested and supervised by a doctor.
Good candidates for a short-term low-residue diet are people who have one of the following conditions or are about to undergo one of these procedures:
- Crohn’s disease,
- Ulcerative colitis,
- Diverticulitis,
- Irritable bowel syndrome (IBS),
- Before a colonoscopy,
- After bowel surgery or some other operations on the digestive tract,
- During a gastrointestinal infection or virus that involves diarrhoea or vomiting.
On the other hand, this diet should be avoided by anyone who has problems with constipation or is trying to control their blood sugar or lower their cholesterol, as well as by anyone for whom it has not been prescribed by a doctor or clinical dietitian.
Low-residue diet after bowel surgery
After bowel surgery, a low-residue diet is followed temporarily until the bowel heals. VFN recommends it, among others, for patients after resection (removal of part of the bowel), including patients with a stoma. In its leaflet, University Hospital Southampton (part of the UK’s NHS) recommends a lower-fibre diet for the first four to six weeks after bowel surgery.
According to the same leaflet, fibre is then reintroduced gradually, one food at a time in small amounts. A fibre-restricted diet is not recommended in the long term unless a doctor or clinical dietitian specifically prescribes it. Patients with an ileostomy or colostomy receive separate instructions, so follow what your surgeon or stoma nurse has given you. Why you should return to fibre later is explained in the article on high-fibre foods.
At first it is often easier to eat smaller portions more often. VFN recommends spreading food across five to six portions a day and making sure you get enough protein, for example from quark, lean meat or hard cheese. Because the diet contains less fruit and vegetables, VFN advises taking vitamin and mineral supplements. Discuss which ones with your doctor.
What you can eat
So how do you make sure your diet contains as little “residue” as possible? Which foods can your body use with almost no residue?
Grains
- Refined or enriched white bread and plain crackers, such as salted crackers or toast without seeds.
- Porridges, such as semolina or rice porridge.
- Breakfast cereals such as puffed rice and cornflakes.
- White rice, noodles and refined pasta.
According to VFN, suitable bakery products include white baguette-style loaves, white toast bread, rolls, buns and sponge fingers, ideally without caraway, poppy seeds or other seeds. Na Homolce Hospital lists fresh bakery products and bread as unsuitable, and VFN lists wholemeal bread and fresh bread.
Advice on oats varies. VFN allows soup made from fine oat flakes in diet No. 5, but Klaudian Hospital in Mladá Boleslav (Klaudiánova nemocnice) and University Hospital Brno (Fakultní nemocnice Brno) do not recommend them before a colonoscopy. The same applies to breakfast cereals and muesli, which Na Bulovce Hospital (Nemocnice Na Bulovce), University Hospital Brno and Klaudian Hospital all exclude before a colonoscopy.
Fruit and vegetables
The skins and seeds of many fruits and vegetables are full of fibre, so you need to peel them and avoid the seeds.
- Well-cooked fresh vegetables or tinned vegetables without seeds, e.g. asparagus tips, beetroot, green beans, carrots, mushrooms, spinach and peeled, deseeded courgette.
- Boiled potatoes without skins,
- Tomato sauce (without seeds),
- Ripe bananas,
- Soft melons,
- Tinned or cooked fruit without seeds or skin, e.g. apple purée or tinned pears,
- Avocado, only in small amounts, it is not served in the Czech diet No. 5 or before a colonoscopy.
Czech hospitals are stricter about fruit and vegetables than the American list. Before a colonoscopy, the Institute for Clinical and Experimental Medicine (IKEM) excludes tomatoes, melon and peppers, Klaudian Hospital excludes melon, and Na Bulovce Hospital excludes melon, tomatoes, peppers and spinach.
VFN does not include mushrooms in diet No. 5, and the only vegetables it allows are cooked and grated or blended root vegetables, spinach and tomato purée, and finely chopped lettuce. The only raw fruit it allows is ripe banana.
Meat and animal products
Animal products contain no fibre. You can eat beef, lamb, chicken, fish (boneless) and pork, as long as they are lean, tender and soft. Eggs are also fine.
Other foods
American lists also allow the following items, but Czech hospitals exclude mayonnaise, ketchup and soy sauce:
- Margarine, butter and oils,
- Milk as tolerated and dairy products,
- Mayonnaise and ketchup,
- Sour cream,
- Smooth sauces and salad dressings,
- Soy sauce,
- Clear jelly, honey and syrup.
Sweets and snacks
Even on a low-residue diet you can satisfy your sweet tooth. These desserts and snacks can be eaten in moderation:
- Plain cakes and biscuits,
- Jelly, plain puddings and sorbet,
- Ice cream and ice lollies,
- Hard sweets.
Czech hospital materials are more cautious about sweets. VFN includes sponge fingers, sponge roll or cake with apricot jam, quark Bundt cake, pancakes, puddings, quark creams and fruit mousses made from permitted fruit in diet No. 5. For fillings it recommends honey, apricot jam, quark or pudding.
According to VFN, unsuitable foods include chocolate and chocolate sweets, butter and nut biscuits, Christmas plaited bread with raisins and almonds, cream cakes and fried desserts such as doughnuts or drop pancakes. Na Homolce Hospital does not recommend ice cream in diet 5a either. If you fancy a Bundt cake, bake a quark one without raisins or nuts.
Drinks
Safe drinks include:
- Weak tea and instant coffee without milk, but limit caffeine if you have diarrhoea,
- Still water and non-carbonated mineral water,
- Juices without seeds or pulp, e.g. apple, orange and cranberry,
- Strained vegetable juices.
VFN advises drinking mainly water and still mineral water, diluting juices and ciders with water in a one-to-one ratio, and drinking between meals. Among hot drinks it allows tea, grain coffee, decaffeinated instant coffee and weak cocoa, but not fizzy or caffeinated soft drinks or alcohol.
If you have diarrhoea, watch your fluid intake even more carefully, as the body loses more fluid with loose stools. How to deal with acute symptoms is described in our article on stomach flu.
What you must not eat
On this diet, avoid:
- Coconut, seeds and nuts, including those in bread, cereals, desserts, sweets and other foods.
- Wholegrain products, including bread, cereals, crackers, pasta, rice and porridge.
- Raw or dried fruit, such as prunes, berries, raisins, figs and pineapple.
- Most raw vegetables.
- Some cooked vegetables, including peas, broccoli, winter squash, Brussels sprouts, cabbage, sweetcorn (and cornbread), onions, cauliflower, potatoes with their skins and baked beans.
- Pulses, lentils and tofu (although some hospitals, such as Klaudian Hospital (Klaudiánova nemocnice), do allow tofu).
- Tough meat with gristle, smoked meat and fatty sausages and cold cuts (ham and poultry ham are fine).
- Cheeses with seeds, nuts or fruit.
- Crunchy peanut butter, and jam, marmalade and preserves with pieces of fruit or seeds.
- Pickled vegetables and condiments, such as gherkins, olives, sauerkraut and horseradish.
- Popcorn.
- Fruit juices with pulp or seeds, prune juice and pear nectar.
Everyone is different. Some items on the “foods to avoid” list may not bother you, while others on the “foods you can enjoy” list may cause you problems. That is why it is worth keeping a food diary for a few weeks. Track what you eat and how you feel afterwards so you know what suits you.
If you love wholegrain foods, nuts and raw fruit and vegetables, switching to a low-residue diet may be difficult. But if you prefer white bread and pasta, do not mind tinned fruit and vegetables and enjoy snacking on salty crackers and sponge biscuits, it may come naturally.
Remember to follow this way of eating long term only under the supervision of a doctor or dietitian. Although the General University Hospital in Prague (Všeobecná fakultní nemocnice v Praze, VFN) considers Diet No. 5 suitable for long-term use, it recommends taking vitamin and mineral supplements because of the limited fruit and vegetables.
Low-residue diet before a colonoscopy
Before a colonoscopy, the diet has a single aim: to make sure no residue remains in the bowel that could hide the lining and any polyps from the doctor. In its 2019 guideline, whose lead author is Cesare Hassan, the European Society of Gastrointestinal Endoscopy (ESGE) strongly recommends a low-fibre diet on the day before a colonoscopy. The second part of the preparation is a laxative solution which, for a planned examination, the ESGE says is best split into two doses.
However, each hospital gives its own instructions, and these take priority over any article, including this one. You will receive them when you book, and if anything is unclear, call the endoscopy unit in advance, not on the day of the examination.
How many days before a colonoscopy to follow the diet
The length varies from hospital to hospital. The Institute for Clinical and Experimental Medicine (Institut klinické a experimentální medicíny, IKEM) recommends avoiding foods with coarse residue for three days before the examination, Klaudian Hospital (Klaudiánova nemocnice) in Mladá Boleslav and Bulovka Hospital (Nemocnice Na Bulovce) for five days, and University Hospital Brno (Fakultní nemocnice Brno) for seven days.
A longer diet is not necessarily better. In a 2021 randomised study by Machlab and colleagues in the journal Digestive Endoscopy, involving 855 participants in bowel cancer screening, 97.9% of people on a one-day diet and 96.9% on a three-day diet had a well-prepared bowel, and participants tolerated the one-day diet better. Even so, follow the diet for as many days as your hospital specifies.
What to eat the day before a colonoscopy
The diet is strictest on the day before the examination. IKEM allows only a light breakfast, such as tea without milk, white bread and yoghurt, then just clear broth without meat, vegetables or pasta, or sweet tea, for lunch, and only fluids in the evening. FN Brno lists instant coffee without milk or tea and one plain white roll with no seeds or toppings for breakfast, and clear broth or bouillon for lunch.
Klaudian Hospital allows plain yoghurt without fruit or cereal for breakfast and only strained broth for lunch, while at Na Bulovce only fluids are allowed from the morning. In the afternoon or evening, you start drinking the laxative solution according to the schedule, and on the day of the examination you arrive with an empty stomach.
Coffee, bananas and eggs before a colonoscopy
The instructions we reviewed do not ban coffee completely; the main problem is milk. IKEM prohibits coffee or tea with milk and milk drinks on the day before the examination, while FN Brno allows instant coffee without milk at the last breakfast and lists Turkish coffee as unsuitable.
Na Bulovce mainly allows instant coffee, and not even that while you are drinking the solution. Klaudian Hospital does not allow ground coffee on the day before the examination.
A ripe banana is one of the few raw fruits that Czech instructions allow, and you will find it among the suitable foods at VFN, FN Brno and Na Bulovce. However, none of these hospitals lists it in the instructions for the day before the examination.
Eggs are allowed by Klaudian Hospital, for example. In Diet No. 5, VFN recommends at most one whole egg a day worked into a dish and egg whites without restriction, and rules out fried eggs.
Fluids and the laxative solution
Fluids are just as important as food during preparation. IKEM wants you to drink at least two litres of fluid in the last three days before the examination, and FN Brno expects at least four litres, including the solution, on the day before. Clear fluids are suitable, such as still water, clear broth, coffee and tea without milk and clear fruit juices, as listed by Bulovka Hospital.
Milk, juice with pulp, fizzy drinks and alcohol are unsuitable. According to the ESGE, start drinking the last dose of laxative no earlier than five hours before the colonoscopy and finish it at least two hours beforehand.
IKEM and Na Bulovce want you to finish drinking three to four hours before the examination, and FN Brno five hours beforehand for examinations under analgosedation with an anaesthetist. Follow the time given in your instructions.
The preparation is sufficient when only clear fluid is coming out of the bowel. If this is not happening, IKEM says you should tell the nurse before the examination, and Bulovka Hospital advises not to skip the morning dose even if clear fluid is already coming out the evening before.
Both IKEM and FN Brno want you to stop taking iron supplements a week before the examination, because according to IKEM they make it harder to flush the bowel. However, do not stop taking blood thinners, diabetes medication or other regular medicines on your own; agree on this with the doctor who referred you for the examination.
IKEM also asks you to stop taking anti-diarrhoea medicines, for example those containing loperamide or codeine, three days before the examination. Hormonal contraceptive pills may not be fully effective because of the bowel preparation, so IKEM recommends also using a condom for the next seven days.
IKEM advises people with diabetes to measure their blood glucose before each meal and before bed on the day before the examination, and to discuss their diabetes medication doses with their diabetologist. They must also follow the low-residue diet.
What to eat after a colonoscopy
After a routine examination without a major procedure, FN Brno says you can start drinking and eating as soon as the sedatives wear off. On the first day, however, avoid foods that cause bloating, spicy foods and fatty foods.
If your doctor removed a polyp, follow the regime they set for you; FN Brno decides this individually for such procedures. According to FN Brno, you must not drive for at least eight hours after sedation, so arrange for someone to accompany you.
3-day meal plan before a colonoscopy
The following sample meal plan is made up of foods that VFN considers suitable for Diet No. 5 and that hospitals list in their colonoscopy instructions. It assumes a three-day preparation, as at IKEM. If your hospital wants five or seven days, repeat the first two days, and if it bans any of the foods, leave them out.
Milk as a drink on its own is deliberately not included in the meal plan. VFN allows it in the diet only if tolerated, and IKEM bans milk drinks on the day before the examination.
Three days before the examination
From the first day, avoid wholegrain bread, pulses, nuts, seeds, raw vegetables and fruit with skin or seeds. Boil, stew or bake your food so that no hard crust forms.
- Breakfast. A white loaf or bread roll with butter and processed cheese, tea.
- Mid-morning snack. A ripe banana or plain yoghurt without fruit pieces.
- Lunch. Broth with noodles, boiled lean beef and mashed potatoes.
- Afternoon snack. Sponge biscuits and apple purée.
- Dinner. Baked cod, crushed potatoes without skins and carrot purée.
Drink water or tea throughout the day, not just with meals. If a meal does not agree with you, leave it out the next day too.
Two days before the examination
The same rules apply on the second day. Vary your protein sources, such as meat, fish, quark and eggs in dishes, so that the meal plan is not monotonous.
- Breakfast. Semolina porridge, tea.
- Mid-morning snack. Plain yoghurt with apricot jam without fruit pieces.
- Lunch. Stewed skinless chicken, white pasta and stewed carrots blended into a purée.
- Afternoon snack. Quark with honey and a bread roll.
- Dinner. Ham, white bread and processed cheese.
Some hospitals, such as Klaudian Hospital, do not allow yoghurt with jam before a colonoscopy. In that case, choose plain yoghurt with no additions.
On the evening of the second day, get your shopping ready for the last day, such as tea, broth and clear juices without pulp, and check what time you should start drinking the laxative solution.
The day before the examination
On the day before the examination, follow your hospital’s schedule exactly, as this is where the instructions differ most. The following day is based on the instructions from IKEM and FN Brno.
- Breakfast. Tea without milk and one white bread roll or plain yoghurt without fruit.
- Lunch. Only clear strained broth without meat, vegetables or pasta.
- Afternoon and evening. Only clear fluids and the laxative solution according to your hospital’s schedule.
On the day of the examination, do not eat anything and drink only for as long as your instructions allow. Take your morning medicines with water as agreed with your doctor.
Sample day on a low-residue diet
Your day might look something like this. The example is based on an American template, which we have adapted to Czech hospital guidelines. Before a colonoscopy, follow your own hospital’s instructions or the meal plan above.
Breakfast
- Decaffeinated coffee with milk (as tolerated) and sugar,
- A cup of juice, for example pulp-free orange juice, apple juice or cranberry juice,
- Semolina porridge,
- White bread with ham or processed cheese,
- Pancakes with apricot jam or white bread with butter,
- White bread toast with margarine and fruit jelly (without seeds).
Lunch
- Roast chicken, white rice, tinned carrots or green beans,
- Salad with roast chicken, processed cheese, a smooth salad dressing and a white roll.
- Mashed potatoes with butter and stewed carrots,
- Stewed lean beef with a white bun without seeds and a smooth sauce.
Dinner
- Tender roast beef, white rice, boiled carrots or spinach, a white roll with margarine or butter.
- Pasta with butter or olive oil, white bread, a fruit smoothie.
- Roast chicken, white rice or baked potatoes without skin, and boiled green beans.
- Baked fish, white rice and tinned green beans.
Low-residue diet recipes
Recipes for a low-residue diet are based on several principles set out by VFN. Food is boiled, stewed or baked without fat under a lid so that no crust forms, meat is not fried, and sauces are not thickened with a roux but with flour toasted in a dry pan. Butter is added only to the finished dish.
Avoid hot spices, pepper, chilli and curry. You can season with parsley, dill, marjoram, basil, sweet ground paprika or bay leaf.
Semolina porridge
Pour four to five spoonfuls of fine semolina into half a litre of milk while stirring constantly, add a pinch of salt and cook over a low heat for about five minutes until the porridge thickens. Sweeten with sugar or honey and add a knob of butter on the plate.
Instead of cocoa and cinnamon, top it with a teaspoon of apricot jam or a mashed ripe banana. If you cannot tolerate milk, cook the porridge with water and add more butter at the end.
Stewed chicken with rice and carrots
Cut skinless chicken breasts into cubes, briefly brown them in a dry non-stick pan, add water or stock, season with salt and stew under a lid until tender, for about twenty minutes. Thicken the juices with a spoonful of flour toasted in a dry pan and finally stir in a knob of butter.
Peel the carrots, boil them until soft and blend into a purée. Serve with white rice. If your clinic does not allow rice before a colonoscopy, as is the case at FN Brno, replace it with mashed potatoes or white pasta.
Baked cod with mashed potatoes
Season a fillet of cod or another lean fish with salt, drizzle with lemon juice, wrap in foil with a knob of butter and bake in an oven preheated to 180 °C for about twenty minutes. In the foil, the fish will not dry out or form a crust.
Boil peeled potatoes in salted water and mash them with butter and warm milk, or, if you are intolerant to milk, with a little of the cooking water. Sprinkle the finished dish with chopped parsley or dill.
Quark cream with banana
Whisk a tub of low-fat quark with a little milk or plain yogurt until smooth and sweeten with honey or sugar. Finally, stir in a mashed ripe banana.
The cream works well as a snack or dessert instead of chocolate. According to VFN, you can swap the banana for apricot or peach compote without skins, blended until smooth.
When to return to fibre
A low-residue diet is prescribed for people with certain conditions or illnesses and is meant to be a short-term dietary measure that helps manage their symptoms. Do not try it at home unless a doctor or dietitian recommends it.
If you have been prescribed the diet, work with a dietitian to make sure you are getting the nutrition you need to support the health goal you are trying to reach or the condition you are trying to improve. After a while, you will start adding more fibre back into your diet.
Add fibre gradually, one food at a time and in small portions, just as after bowel surgery. What helps the gut during this period is described in the article how to restore your gut microbiome.
