Despite the misconception that irritable bowel syndrome (IBS) can cause changes in weight gain or loss, there are no clinical connections between IBS and weight. Neither loss nor gain is a symptom of IBS. The only real connection between the two is that many who suffer from IBS also consume foods which may exacerbate the condition. These are often high in fat and calories, so they may be restricted as part of an IBS treatment plan, resulting in weight loss.
It should be noted that there are no specific foods which cause or trigger IBS symptoms in every sufferer. Every person with the condition may have his or her own trigger foods which cause symptoms to occur. That said, there are certain foods which are harder to digest in general. Among them are dairy items and heavily processed foods, both of which can also cause weight gain if not eaten in moderation.
Since patients with irritable bowel syndrome are often instructed to avoid foods which cause a flare-up of symptoms, there may appear to be a connection between IBS and weight if the patient suddenly begins to lose weight upon being diagnosed with the condition. This is generally not the case and weight loss is simply from avoiding overly fatty or processed foods.
The opposite would also hold true. Some may find that eating certain things reduces symptoms and begin eating them more regularly and in higher quantities. This may seem like IBS and weight gain are related, but eating more of anything can result in added pounds.
If IBS and weight gain or loss seems to occur simultaneously, and there have been no significant increases or decreases in food consumption, an underlying medical condition may be to blame. Sometimes constant or severe stomach pain may cause patients to avoid eating entirely, leading to weight loss. If this is the case, a better pain management system should be implemented by a medical professional. Food should not be avoided as a treatment for irritable bowel syndrome, due to the risk of malnutrition.
Patients should also examine what they are drinking, as many people get more than half their daily calories from drinks alone. Drinks like soda, juice, milk, and sports drinks may be consumed in higher amounts to replenish fluids related to IBS-induced diarrhea, but they are not sufficient for hydration and may cause weight gain. Additionally, dairy and carbonated beverages are hard to digest and may increase symptoms.