I've Been Thinking - Dr Shelagh's Blog
People who binge may take laxatives to influence their shape and weight, though the practice is less common than self-induced vomiting and is pursued mainly by people with bulimia nervosa. Some people take very large quantities, as many as 50 or 100 at a time. Regardless of the amount taken, laxatives have little effect on calorie absorption. They act on the lower part of the gut, whereas calories are absorbed higher up. What they do produce is watery diarrhoea and a temporary fall in weight due solely to loss of water. The person regains the lost weight almost immediately as the body re-hydrates. Nevertheless, people with bulimia nervosa find the weight loss rewarding, believing that it is evidence of an effect on calorie absorption, which is the main reason they persist in taking laxatives. As with self in-induced vomiting, one wonders how many people would never begin using laxatives if they new how ineffective they are.
Laxative misuse, like self-induced vomiting, produces a variety of fluid and electrolyte abnormalities with symptoms of the type just described. Individuals who both vomit and misuse laxative are at particular risk. Some laxatives, when taken in high doses over long periods, result in permanent damage to the gut wall. Generally however, the adverse physical effects are reversible. Someone who has taken laxatives regularly may retain fluid (water) for a week or so after stopping suddenly. Obviously this will produce a temporary weight gain.
Some people take diuretics (water tablets), usually over-the-counter preparations, to change their shape and weight. Again, this is a fruitless exercise since diuretics have no effect on calorie absorption. Like laxatives, they cause fluid loss, in this case through the production of excess urine, and thus have a short lived effect on body weight. When taken in large quantities, they can produce fluid and electrolyte disturbance. This is reversible. As with laxatives, those who stop taking diuretics after having used them for some time may experience temporary fluid retention. Clearly they should not take further diuretics at this point, or they establish a vicious circle.
Fertility and Pregnancy
We know that dieting and weight loss impair fertility, an effect that is generally reversible provided weight is stabilised within a healthy parameter. It is well established that during pregnancy those with anorexia nervosa are at risk of gaining too little weight and may give birth to underweight babies, and the same may be true of mothers with bulimia nervosa. The findings of a study done by researchers at the University of Minnesota suggest that among women with bulimia nervosa the miscarriage rate may be increased. This finding, however, requires confirmation. More harmful are likely to be the weight control behaviours of extreme dieting, vomiting, and the misuse of laxatives or diuretics.
To date little research has been done on the effects of binge eating problems on fertility and pregnancy. The influence of binge eating on its own has not been studied. Binge eating is unlikely to affect the course or outcome of pregnancy, although when it is associated with obesity the risk of complications such as high blood pressure increases.
Dieting As A Cause Of Unfertility
Some women with unexplained infertility are strict dieters. Often they are underweight. When 29 such women were referred to a weight gain program, 26 of them gained enough weight to be near their ideal. 19 of these women (73%) subsequently conceived spontaneously. 3 would not accept the idea that dieting might be responsible for their infertility. None of these women returned for further care.
Source: Bates GW, Bates SR, Whitworth NS . Reproductive failure in women who practice weight control. Fertility and sterility 1982; 37: 373-378.
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