With approximately 1.25 million people in the UK living with an eating disorder (www.beateatingdisorders.org.uk), Eating Disorder Awareness week (2-8 March, 2020) is an important week to shed some light on the complexities involved and how it physically can affect your gut.
Renee McGregor, leading sports and eating disorder specialist dietician with 20 years of experience in this field shares how eating disorders can impact the gut.
What’s the cause?
Eating Disorders are complex mental illnesses; often highly misunderstood and poorly supported. They are rarely about food or even body image, they are generally a coping mechanism when life feels too uncomfortable and chaotic to deal with.
Contrary to what is often believed, an eating disorder is rarely caused by diet culture; while it may contribute, there are 3 more established pathways that cause dysfunctional relationships with food:
An individual is susceptible to developing a difficult relationship with food due to their personality traits and also genetic links. If there is a family history of mental health issues, this increases the risk of one developing; that is not to say it is set in stone.
Individuals that develop a perfectionist mindset are most at risk; they are also often determined, focused, obsessive, compulsive, highly critical and at the same time-sensitive. These traits create a notion that they are not enough; no matter what they do, they should be able to do more. They interpret situations and comments critically, thus creating a negative narrative about themselves. When this feels impossible to experience, they look for ways to contain this – food provides them with one medium that they can physically control to temporarily numb their pain.
It is well documented that if someone displays one form of extreme behaviour such as addiction, they are more likely to develop another. This is also why there is a higher prevalence of eating issues in those that are athletes 
Indeed, a recent study  showed that exercise addiction occurs more than three and a half times as often as a comorbidity to an eating disorder than in people without an indicated eating disorder.
When someone experiences trauma whether this is a loss of a parent, an accident or sexual assault, it creates a whole set of emotions that can be difficult to experience. Life can feel unbearable and individuals need a way of expressing pain and discomfort. For some becoming as small as possible helps them to demonstrate how insignificant they feel; for others punishing themselves through starvation and over-exercising feels like their only solution to deal with their trauma. Fundamentally it is the need to escape those difficult emotions; restricting intake results in a numbing effect, albeit temporary and sadly with longer-term health consequences.
So what starts as a psychological concern, rapidly creates behaviours that have significant implications for an individual’s physical health.
Effect on body and mind
As with most illnesses and problems, it is very easy to oversimplify. In the case of eating disorders, often it is compartmentalised; seen as two entities – the body and the mind. And yet, you cannot impact one part of you and not expect it to have an effect on another. While dysfunctional behaviours around food may provide solace temporarily, the lack of energy being consumed means that the body has to prioritise certain biological functions (heart, brain, lungs) in favour of others (hormones, bones, blood, digestion).
In reality, the body dials right down in order to preserve energy and keep the individual alive. It is known that in severe cases of lack of energy, the brain will go from using its required 120g of glucose a day to as little as 60g in order to preserve energy. When it falls below 40g it becomes a serious problem and will actually start to metabolise its own neurons (cells that carry information from the brain to other parts of the body) for energy.
How this affects the gut
As the body dials down on metabolism into preservation mode, one of the areas that is hugely affected but never spoken about is the digestive tract. Indeed many individuals that present in clinic, often report “irritable bowel” like symptoms – bloating, discomfort, early fullness, nausea. However, this is far from IBS. More recently there is also emerging evidence about the role of the intestinal microbiota and the brain-gut axis. While there are some very exciting discoveries, their role within the treatment of functional gut disorders as a result of eating disorders still needs more research.
In Anorexia, this is often a result of gastroparesis or delayed stomach emptying and is a result of not sufficient energy within the body to allow for normal digestion. It is often exacerbated as the foods that individuals with Anorexia tend to fill up on are high fibre fruit and vegetables or sugar-free foods/drinks containing artificial sweeteners which are both known to contribute to the production of gas.
The usual pattern of eating adopted by most individuals with Anorexia– saving their calories until the evening and consuming over a short period of time, accompanied by an already muscularly weak stomach, adds to the issue.
Refeeding is a vital process in recovery from Anorexia but these digestive symptoms can make it very uncomfortable, and often hinder recovery. Equally, if these individuals are misdiagnosed with IBS and a FODMAP diet encouraged, not only does this feed into their already restrictive and exclusion mindset, it further reduces energy intake and makes the situation a lot worse.
In Bulimia, it is the upper GI tract that is most often impacted due to recurrent induced vomiting. The valve between the oesophagus and stomach can become floppy allowing for acid reflux symptoms. Additionally, individuals may experience gas, bloating, indigestion and constipation as well as gastritis, an inflammation of the lining of the stomach causing upper abdominal pain.
Laxative abuse has been reported in more than 1/3 of patients with eating disorders. Patients believe they are purging calories to stay thin, when in fact, most absorption of calories occurs in the small intestine. Most commonly (though not exclusively) seen in patients with bulimia, laxative abuse causes the bowel to become dependent on laxative stimulation to pass a bowel movement. Individuals who use laxatives, diuretics or both (to purge calories) become severely and chronically dehydrated.
There are different impacts depending on the type of laxative – some cause over-stimulation of the bowl while others add bulk to stool. In all cases, practitioners need to carefully monitor patients as they wean off laxatives as there can be severe consequences.
Individuals who binge-eat tend to have erratic and irregular eating patterns around all meals, in turn causing a host of GI symptoms including constipation, gas, bloating and diarrhoea.
What to do?
In all cases best practice in treating these symptoms is normalizing eating patterns, encouraging regular intake of 3 meals and 3 snacks, 3 hours apart. However, care must be taking in reintroducing foods and is best under the guidance of a specialist dietitian and medical profession as a multidisciplinary approach.
If you or someone you know needs support for an eating disorder or suspected eating disorder, please seek help from your GP or medical professional. In addition, other organisations offer support include:
A comparative meta-analysis of the prevalence of exercise addiction in adults with and without indicated eating disorders.
Trott M, Jackson SE, Firth J, Jacob L, Grabovac I, Mistry A, Stubbs B, Smith L.
Eat Weight Disord. 2020 Jan 1. doi: 10.1007/s40519-019-00842-1. [Epub ahead of print] Review.
PMID: 31894540 https://www.ncbi.nlm.nih.gov/pubmed/31894540
2016 update on eating disorders in athletes: A comprehensive narrative review with a focus on clinical assessment and management.
Joy E, Kussman A, Nattiv A.
Br J Sports Med. 2016 Feb;50(3):154-62. doi: 10.1136/bjsports-2015-095735. Review.
PMID: 26782763 https://www.ncbi.nlm.nih.gov/pubmed/26782763