With so much emphasis being placed these days on the mortal hazards of overweight and obesity, it can sometimes be easy to forget that unduly low body weight poses risks for health too. Sufferers of anorexia nervosa, for instance, can exhibit such extreme weight loss that hospital treatment is deemed necessary. It is well known, however, that when such intensive therapy is deemed successful in terms of weight gain, a high percentage of sufferers go on to relapse. Also, research published this month in the American Journal of Clinical Nutrition has found that even after hospital-based treatment, anorexics still tend to have a tendency to unhealthy food restriction. It seems that even after heavyweight medical treatment, sufferers of anorexia nervosa often remain lean and hungry.

While the causes of anorexia nervosa may be complex and may often relate to psychological and social factors, there is at least some evidence that disordered physiology may play a role in the development of the condition too. In particular, research has suggested that anorexia may be related to a deficiency in the mineral zinc. Zinc deficiency has been found to be a common feature in anorexics, and it has been noted that zinc deficiency and anorexia nervosa have symptoms in common which include poor appetite, weight loss, nausea and cessation of periods (amenorrhea).

These findings have led some scientists to suggest that zinc deficiency may actually play a role in the causation of anorexia nervosa. The role between zinc and eating behaviour may be connected to a brain chemical known as neuropeptide Y (NPY), the main function of which is to stimulate eating. Generally speaking, restriction of food causes an increase in NPY levels. Animal research has discovered, however, that zinc deficiency blunts the increase in NPY in response to food restriction. The results of this research suggest that zinc deficiency may quell the normal urge to eat more should food be rationed.

Support for the idea that zinc deficiency plays an important role in anorexia nervosa has come from a study which found that zinc supplementation appeared to promote significant weight gain in 17 out of 20 anorexics. In another piece of research, zinc supplementation doubled the speed of weight increase in a group of anorexic women compared to supplementation with placebo (inactive medication).

The mainstay nutritional approach in anorexia nervosa should be a diet based on truly nutritious foods such as fish, fruits, vegetables, beans, lentils, nuts and seeds. Nuts and seeds may have special significance here as some of these (such as pecan nuts and pumpkin seeds) are good sources of zinc. In addition, it may help anorexics to supplement with zinc. Well-absorbed forms of zinc include zinc picolinate and zinc citrate. I generally recommend that these are taken at a dose of 50 - 100 mg per day. The evidence suggests that zinc supplementation can add weight to more conventional treatments for anorexia nervosa.

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