13 January 2021

Section 9: Bowel habits and bowel health

Bowel Health

To maintain optimal bowel health, adults are recommended to aim for 30g of fibre per day. Among many other health benefits, fibre is essential in managing both constipation and diarrhea and it has been shown to reduce the risk of developing bowel cancer. The best way to ensure that you are getting a variety of fibre in your diet and meeting your needs is by choosing foods which are rich sources, such as whole grain cereal, granary bread, pulses, fruits, and vegetables.

In general, it is normal to move our bowels as frequently as three times as day and as infrequently as three times per week.  However, after undergoing bariatric surgery this may change and you may move your bowels more or less frequently than before.  As a rule of thumb, if after surgery you have bowel movements more than three times per day or less often than every three days, and if the consistency is too loose or too uncomfortable to pass, and you have tried the common remedies described below, speak to a healthcare professional.  You should never see blood when opening your bowels; if you see blood, call your GP without delay.


There will be a reduction in the volume of your stools after surgery, which is caused by a decrease in food volume, ingesting less fibre during the fluid/pureed phase and/or consuming insufficient fluid. The main method of prevention is to drink sufficient amounts of fluid. The following general principles will help you to restore a normal bowel pattern after surgery:

  1. Drink plenty of fluids – this does not have to be just water. Suitable fluids include sugar-free/no-added-sugar flavoured water, tea/coffee, herbal/fruit teas, sugar free/no added sugar squash. During the fluid stage, meal replacements, milk and soup also count.
  2. Exercise regularly in accordance with the guidelines in Physical Activity.
  3. Include prunes or unsweetened prune juice in your daily diet. Dilute juice 50:50 with water to prevent consuming too much sugar in one go as this could cause Dumping Syndrome (see Dumping Syndrome).
  4. Introduce high fibre foods to your diet, e.g. high fibre crackers (e.g., Ryvita, Finncrisp), cereals, potato skins, and wholewheat pasta as soon as you progress back onto textured/solid foods 4 - 6 weeks post-op. During the puree and soft food stages (weeks 3 and 4 respectively), you can include soft high-fibre foods such as Weetabix and porridge (pureed during the puree stage).
  5. Include fruit and vegetables in your diet every day, taking into account the stage you are on (see Follow up and General Guidelines).

If constipation persists, you may need to try taking a natural laxative such as Senna (remember to take in liquid form in the first 8 weeks).  If this is ineffective, see your GP for a prescription of lactulose, but it is best if you contact us to speak with a dietitian or nurse in the first instance.



Diarrhoea can be a problem after any gastric surgery. This can be caused by the movement of your digestive tract being upset. If this occurs, try sticking to bland foods and ensure you are drinking sufficient fluid.  Loperamide (e.g., Imodium) can also be used to relieve this.


If you have had a gastric bypass, diarrhoea can also occur due to eating too much fat. Take measures to reduce your fat intake - e.g., remove fat from meat, use 1% fat or skimmed milk, try reduced fat or half-fat cheese instead of full fat, limit oil when cooking and spread on toast/bread/crackers.


Loose stools may also occur due to dumping syndrome, where in response to eating sweet or fatty foods fluid is mobilised into the small bowel.  Ensure that you are not ingesting undiluted fruit juice, syrup, honey or sugar sweetened foods or beverages.  



Wind pain initially post-surgery is discussed in Bowel Habits and Health. Further down the line, wind only usually occurs due to poor eating technique. Make sure you are taking small mouthfuls, chewing well and eating slowly.  The remedies described in Section 7 can still be effective i.e. peppermint tea, gripe water, Deflatine/Wind-eze.




It is not uncommon to suffer from excess flatulence with these types of surgery, especially gastric bypass. This is due to undigested food reaching the large intestine and fermentation occurring. It can also be due to eating too quickly, which can mean you ingest air while you eat. Another reason for this symptom could be intolerance to a specific food so contact us to arrange a consultation with a dietitian who will be able to provide further advice; keeping a food and symptom diary can also be useful.


A healthy bowel motion would resemble Type 3 or 4 on the Bristol Stool chart.     



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