Written by Sophia Boothby, with introduction & review by Talia Cecchele
Digestive issues often coincide with eating disorders and can temporarily worsen during nutritional rehabilitation. It is a bit of a chicken or egg scenario as digestive issues can result in unintentionally following a restrictive diet to manage symptoms, which can negatively influence a person’s relationship with food. And on the other hand, following a restrictive diet can cause digestive issues.
For some people, digestive issues such as Irritable Bowel Syndrome (IBS) may have been present before an eating disorder developed, and for others, IBS symptoms can present and persist even after full recovery.
A restrictive elimination diet, known as the Low FODMAP Diet is sometimes recommended by health professionals to manage IBS symptoms. This diet needs to be carefully considered as it can be inappropriate to follow if someone is at risk of developing disordered eating, has an eating disorder or a lived experience of one.
What is the Low FODMAP diet?
FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols.
These are complex names for different types of fermentable carbohydrates or prebiotic fibres that are found in a variety of foods (for example, wheat containing breads and cereals, some fruit and vegetables, pulses, artificial sweeteners and dairy foods). For some people, when FODMAPs are eaten, the body poorly absorbs them and they pass through to the large bowel, where bacteria ferment them, producing gas and potentially drawing water into the large bowel, which can present unpleasant digestive symptoms (1).
The Low FODMAP diet is recommended as second line treatment when people experience IBS symptoms. It includes three phases; an elimination phase, reintroduction phase and the personalisation phase.
Elimination: this first phase is what most people refer to as the Low FODMAP diet. What's important to remember is that this should only be followed for 6-8 weeks maximum for diagnostic purposes. In practice, unfortunately, many clients walk through our doors having followed the elimination diet for many months or even years.
Reintroduction: this involves reintroducing and challenging FODMAPs to test your tolerance levels and identify your threshold level.
Personalisation: this involves a modified low FODMAP diet, personalised to the results from the reintroduction phase.
Please note: we strongly advise against following the low FODMAP diet without the guidance from a trained registered dietitian.
When should you try the low FODMAP diet?
Irritable Bowel Syndrome is a disorder of the gut-brain axis, which suggests that there are interruptions in the connection between the gut and the brain. Changing what we eat though, isn't the only solution to the wellbeing of our gut.
The low FODMAP diet is not first line dietary treatment for IBS. First line dietary approaches usually focus on diversifying dietary fibre in the diet, fluids, caffeine intake and meal regularity. British Dietetic Association summarises first line treatment to also include non-dietary approaches such as regular movement, mindfulness and stress-relief advice (2).
If first line treatment is unsuccessful in managing IBS symptoms, this is where the Low FODMAP diet comes in. It should only be recommended after all relevant first line treatment strategies have been trialed.
Deciding to try Low FODMAP diet
If your quality of life continues to be affected by your IBS symptoms following implementation of first line treatment, trying the Low FODMAP diet is the next step to consider. If you are working with a Dietitian alongside recovery from an eating disorder then ultimately you should determine the suitability of this for you personally. Following a restrictive, elimination diet can be counterproductive for your recovery so it is important to receive the right support.
PROS of following the Low FODMAP Diet
Evidence-based second line dietary treatment for IBS proven to reduce symptoms in 75% of individuals with IBS (1,3)
Provides a structured approach (with an end date)
Identifies specific food triggers during the second phase of the low FODMAP diet as individual FODMAPs are introduced, with potential to expand diet variety again
Introduce foods that might have been previously feared or associated with IBS symptoms
Improve quality of life through increased flexibility with food choices
CONS of following the Low FODMAP Diet
When not followed with the guidance of a trained dietitian, some people remain stuck following this restrictive diet for months or years out of fear of reintroducing trigger foods again
Increased anxiety around foods or social settings and potential to further restrict diet if food intolerances are discovered in phase one
It can be used to mask disordered eating and an excuse not to challenge food and increase food variety
Increase time thinking about food which can lead to obsessive thinking
Difficult to eat out at restaurants or in social situations
Create a negative relationship with food and develop disordered eating behaviours
Not recommended for women who are pregnant or children. There is insufficient evidence for either group.
What about a modified Low FODMAP diet?
Although the first phase of the low FODMAP diet can take up to 8 weeks, once you reach the final personalisation phase you are aiming to return to a diet with as little restrictions as possible. However, this can take time with lots of trial and error which might not be suitable for someone in recovery or with a history of an eating disorder.
A modified approach might mean that not all FODMAP categories are eliminated and challenged, or the personalisation phase will be tailored so that a less restrictive diet can be followed. A modified Low FODMAP diet is generally something to consider further along in recovery, as weight restoration and restoring physical health alone can improve gut symptoms. It is important to work with a registered dietitian who can tailor advice based on your history and digestive symptoms experienced.
Dietary restriction & gut symptoms
Following the Low FODMAP might not be the solution to IBS symptoms. Some people will not respond to the elimination phase (or their symptoms actually worsen). This is an important reminder, that when it comes to gut health having variety in what we eat nourishes our gut. A restrictive diet can lead to an undernourished digestive system.
Low FODMAP diet and eating disorders
When we are aiming towards finding food freedom and creating a positive relationship with food, habits such as following a pattern of regular balanced meals or snacks every 2-3 hours, reducing stress around mealtimes, adequate daily hydration, intuitive movement and mindfulness are all strategies that can improve gut symptoms.
If you have disordered eating or are in recovery from an eating disorder, the Low FODMAP diet is in most cases, not appropriate, as it is too restrictive and can worsen a person's relationship with food, often triggering further dietary restriction in the long-term (4), all of which can worsen gut health. A key take-away message is to aim towards improving gut health using strategies that don’t focus on dietary restrictions as the first approach and to seek support from a specialist dietitian.
At TCN our specialist eating disorder dietitians can offer online consultations to support your gut health journey! Book a free 15 minute discovery call here with one of our dietitians.
Sophia is a Specialist Community Dietitian within a London NHS Teaching Hospital specialising in gut health such as irritable bowel syndrome (IBS) and the low FODMAP diet, type 2 diabetes, PCOS, cardiac rehabilitation, and oral nutrition support. Sophia has recently developed her practice incorporating a non-diet and weight inclusive approach to nutrition with individuals presenting with disordered eating and restrictive eating behaviours, particularly alongside IBS. Find Sophia on Instagram at @eatforyoudietitian
National Institute for Health and Care Excellence (NICE), 2008. Clinical guideline [CG61] Irritable bowel syndrome in adults: diagnosis and management. National Institute for Health and Care Excellence. Available at: Irritable bowel syndrome (nice.org.uk) [Accessed 10 January 2023].
British Dietetic Association (BDA) UK Website. 2022. Irritable Bowel Syndrome Food Fact Sheet. [online] Available at: <https://www.bda.uk.com/resource/irritable-bowel-syndrome-diet.html> [Accessed 20 September 2022].
Marsh, A., Eslick, E.M. and Eslick, G.D., 2016. Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and meta-analysis. European Journal of Nutrition. [online] 55:897-906. Available at: https://doi.org/10.1007/s00394-015-0922-1 [Accessed 11 January 2023].
Sato, Y. and Fukudo, S., 2015. Gastrointestinal symptoms and disorders in patients with eating disorders. Clinical journal of gastroenterology. [online] 8(5):255-63. Available at: https://doi.org/10.1007/s12328-015-0611-x [Accessed 10 January 2023].
Talia Cecchele Nutrition is a team of registered dietitians that specialise in eating disorders, disordered eating, digestive issues and sports nutrition. We aim to bring balance back to nutrition, help you to break free from food rules and find food freedom. We offer virtual consultations and group programs so whether you are based in London, the United Kingdom or around the world we would love to support you. To enquire about a private consultation please fill out a contact form.
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