A significant change in body weight can be a symptom of IBS. Generally, weight gain or loss occurs with an increase or decrease in the calories consumed in relation to those being expended.
However, in the case of IBS there may be more complicated underlying issues as a change in weight is often not intentional. Both cases of weight loss and weight gain have been linked to IBS and below we discuss the possible mechanisms involved.
There are a number of possible explanations as to why IBS might result in weight gain.
A change in diet in an attempt to reduce symptoms can be a factor. Many types of fruit and vegetables can actually act as triggers in IBS as they often contain indigestible components which undergo fermentation in the large intestine. Learn more on the FODMAP diet and how cutting out some of these foods may help to improve your symptoms.
As a result of recurring flare ups you might be tempted to replace fruit and vegetables with carbohydrate sources instead, such as potatoes or rice (which are generally more calorie dense and hold a lower nutritional value) which can cause weight gain.
Mental factors may also have a role to play. IBS is often linked to psychological issues such as anxiety or depression which can be associated with emotional eating. Over-eating may be a result of feeling particularly down or when your symptoms have subsided and you feel happier. Read our blog on how emotions can affect our eating habits and weight.
Episodes of constipation can also cause temporary weight gain as the weight of excess waste material and water are stored and reabsorbed in the colon.
Diarrhoea dominant IBS may result in weight loss. Diarrhoea is characterised by the abnormally fast transit of food through the gut. This means necessary calorific macronutrients, plus essential vitamins and minerals may be malabsorbed.
The symptoms of IBS vary greatly from person to person but pain, nausea and loss of appetite are common. These particular symptoms can affect our appetite and result in us expending more energy than we are consuming meaning we are likely to lose weight.
There are some steps you can take at home to help you manage your weight:
- Manage your diet as much as possible: If you realise you are limiting your fruit and vegetable intake, try and experiment with different variations as some may have adverse effects whereas others won’t. See our guide on the FODMAP diet to learn more. If diarrhoea is your issue, try to incorporate foods which may help with this. Soluble fibre binds water and so can lessen the severity of diarrhoea or loose stools. Try to incorporate lots of oatmeal, nuts, beans, lentils, apples and blueberries into your diet
- Relax: If stress or low mood as a result of IBS is affecting your eating habits you may want to address this. A happy mind is more like likely to coincide with healthy eating habits. Specific relaxation techniques such as yoga or meditation can help to relieve stress and boost your appetite
- Drink water: During episodes of both constipation and diarrhoea, drinking water is essential. In constipation, drinking water helps us deal with water retention and can assist in softening stools, allowing them to move more efficiently along the GI tract. In episodes of diarrhoea you may become dehydrated so drinking plenty of water is essential.
It is important to remember that the key to a healthy weight is a wholesome diet and regular exercise. However there are some products which may be useful in supporting weight management.
- Molkosan: If IBS is thought to be the source of your weight change then a product called Molkosan may be useful. Molkosan works well to create an environment to support the good bacteria in our gut. There are millions of strains of bacteria residing in the human gut and early research has suggested these may have a role in weight management as they appear to differ in people who are obese or anorexic. In general though, a healthy gut means a healthy body.
- Kelp: Kelp is high in the mineral iodine. Iodine supports the thyroid gland which maintains our metabolism. A healthy metabolism is crucial for maintaining a stable weight, if too fast we can lose weight and if too slow we may struggle with weight gain.
Armougom, F. et.al (2009) Monitoring bacterial community of human gut microbiota reveals an increase in Lactobacillus in obese patients and Methanogens in anorexic patients. DOI: http://dx.doi.org/10.1371/journal.pone.0007125
If you experience extreme weight loss or weight gain it is advised that you visit your doctor. Depending on the root of the cause they may be able to prescribe some suitable medication.
Medication to support weight loss, such as Orlistat, isn’t often prescribed unless dietary and lifestyle measures are already in place and weight loss is underway.