Driven by the compulsive need to avoid weight gain, many eating disorder sufferers consume large quantities of laxatives in order to rid the body of the food they eat.

Laxatives are a readily available form of medication normally taken to treat constipation. Indeed, sufferers of bulimia and anorexia often complain about constipation and feeling bloated.

Such symptoms occur because the food and fluid their diet supplies are not of the right quality or constitution to enable the bowel to function properly. As a result, their digestive system is slow and inefficient.

While the eating disorder sufferer’s perception of their physical condition might suggest a health benefit in taking laxatives, it fails to address the real cause of their constipation - their psychological compulsion to avoid weight gain.

A loss of weight may occur as a result of inducing diarrhoea directly after taking laxatives and this prompts an individual with bulimia or anorexia to persist, convincing themselves they have found a ‘healthy’ weight loss regime.

However, such short term effects would be misleading because they do not indicate any loss of body mass tissue, fat or calories but, rather, a sudden loss of body fluid leading to dehydration.

Such a sharp loss of body fluid can result in a range of serious problems. Sufferers of dehydration may feel faint, tired and develop painful headaches. A further side effect is bloating, particularly around the stomach and ankles.

Further complications that are quite unrelated to the digestive system can develop as a consequence of dehydration. The fluid normally present in a healthy, properly functioning bowel contains essential minerals. Most important among these is potassium, which plays a vital role in the function of the nervous system. So, a drop in potassium levels can affect the nerves of the heart, causing an irregular heartbeat.

A blood test and electrocardiograph heart rhythm check can offer an accurate indication if a person’s potassium levels are low, in which case potassium tablets may be prescribed. In more serious cases, a patient may be admitted to hospital for a short period so that potassium can be administered through an intravenous drip.

In time, the functioning of the bowel can be further impaired due to weakening of the surrounding wall of muscle, leaving it flaccid and with an impaired ability to contract and push its contents out. This damage to the bowel can be permanent, leading to long-term constipation that will not respond to further treatment with laxatives.

The safest and most effective way to give up misusing laxatives, particularly for people who have been consuming them regularly over a prolonged period, is to reduce intake gradually. Additionally, a carefully controlled return to a healthy diet will help restore proper digestive function. Eating plenty of fruit and vegetables and high fibre, wholemeal food and drinking plenty of water will help restore a good nutritional balance.

It is important for the recovering eating disorder sufferer to remember that the rehydration that will come with their restored health may cause a small weight gain. They should be reassured this is healthy and normal and does not mean their weight will continue to increase in the medium to long-term.