Last week saw the publication of a study in the British Journal of Psychiatry which has found that the eating disorder bulimia nervosa is 5 times more common in cities than in more rural areas . The authors of this study suggested that this difference may be due to the relative anonymity of a big city allowing individuals to conceal their bulimic tendencies more easily than those living in tighter-nit communities.
This may have something to do with it, though there are other potential explanations too. One of these concerns the brain chemical serotonin ” higher levels of which are associated with improved mood and feelings of contentment. Low levels of serotonin are believed to be a factor in the food cravings that can trigger the bingeing episodes typical of bulimia. Serotonin is made in the brain from an amino acid (building block of protein) known as tryptophan. When carbohydrates (sugars or starches) are consumed tryptophan gets an easier ride into the brain, and this can boost serotonin levels. This is one mechanism which helps to explain why bulimics often binge on carb-rich foods such as chocolate, bread or crackers. This theory is supported by studies which have found that inducing depletion of tryptophan actually provokes bulimic symptoms in women with a history of this condition [2, 3].
So, what this all got to do with living in a city? Well, there is evidence that depression is generally more common in urban rather than rural environments. It might be, therefore, that the generally lower levels of serotonin in city-dwellers puts them at great risk of carbohydrate cravings and subsequent bingeing. I don’t know whether this is true or not, but what I do know is that, in practice, taking steps to enhance serotonin levels in the brain often is highly effective in controlling the symptoms of bulimia.
One simple approach that can help here is to get plenty of sunlight, as this natural commodity has been shown to boost serotonin levels in the body . Getting out in the light is particularly important right now for those of us who are in the middle of a cold, dark winter.
Another way to get serotonin levels up is by taking a supplement of the nutrient 5-hydroxytryptophan (5-HTP). This nutrient is actually a chemical stepping stone between tryptophan and serotonin. Effective doses of 5-HTP are generally in the order of 50-100 mg, three times a day.
Another physiological factor that can feature in bulimia is episodes of low blood sugar. Below, I’ve added a piece which explores this specific issue in more depth. My experience is that remedying one or both of these imbalances is usually highly effective in getting bulimic symptoms under control.
Observer Column – 29th February 2004
The National Institute for Clinical Excellence (NICE) here in the UK recently published a report which stressed the role of psychological therapies in the treatment of eating disorders such as bulimia and anorexia nervosa. However, while conventional wisdom has been that these conditions are essentially mental disorders for which a head-first approach should prevail, mounting evidence suggests that disordered eating may be rooted in issues that have more to do with the body, than the brain. In particular, studies suggest that the bingeing of food typically exhibited by sufferers of bulimia may be manifestations of biochemical processes gone awry. Scientific research shows that dietary modification can put pay to the symptoms of bulimia, and is an approach that may be considered to be a no-brainer for those seeking an effective treatment for this condition.
One common cry heard from those suffering from bulimia is that once they start eating, they can struggle to stop. While any food may be the object of a bulimic’s desire, experience shows that most gravitate to carbohydrate-based foods rich in sugar and/or starch. The sort of carb-fest many find themselves engaged in will generally ignite a skyrocketing of blood sugar levels. There is some evidence that this surge in the system has the potential to skew the delicate biochemistry of the brain, and this may have repercussions for both appetite and mood.
In one study published in the journal Biological Psychiatry, an injection of sugar was found to provoke feelings such as depression and anxiety in a group of bulimic women, while a placebo injection did not. Interestingly, women subjected to an influx of real sugar also led to an upsurge in their urge to binge. The precise biochemical mechanism responsible for this phenomenon is unknown. However, the results of this study do at least seem to lend some credence to the common bulimic experience of getting stuck on a roll.
Another hallmark symptom of bulimia is the purging of food from the body, for which induced vomiting and/or laxatives are commonly employed. Interestingly, a study published in the International Journal of Eating Disorders found that purging tends lead to sub-normal levels of blood sugar in the body . The relevance of this is that when blood sugar levels are low, there is a tendency for the body to crave carbohydrate foods, and usually plenty of them too. The available evidence suggests that those suffering from bulimia can be caught in a viscous cycle fuelled by highs and lows of blood sugar.
In practice, I have seen many individuals break this cycle by adopting a diet designed to get blood sugar levels on an even keel. Three meals are day are recommended, and these are best based on relatively slow sugar-releasing foods such as meat, fish, eggs, vegetables and a limited amount of unrefined starch-based foods such as potato, brown rice and wholemeal pasta. Snacks of fresh fruit and/or nuts had between meals can also be useful for keeping blood sugar levels buoyant. Scientific validation for such an approach comes in the form of a study in which 20 bulimic women put on a sugar-stabilising diet . Within three weeks, all 20 of the women had stopped bingeing, and remained free from binges in the long term too. The evidence suggests that a nutritional approach often proves effective for curbing uncontrolled eating, and promises significant benefits for individuals keen to get bulimia out of their system.
1. VAN Son GE, et al. Urbanisation and the incidence of eating disorders. Br J Psychiatry. 2006;189:562-3
2. Smith KA, et al. Symptomatic relapse in bulimia nervosa following acute tryptophan depletion. Arch Gen Psychiatry 1999;56(2):171-6
3. Cowen PJ, et al. Serotonin, dieting, and bulimia vervosa. Adv Exp Med Biol. 1999;467:101-4
4. Lambert GW, et al. Effect of sunlight and season on serotonin turnover in the brain. Lancet. 2002;360(9348):1840-2
5. Johnson WG, et al. Repeated binge/purge cycles in bulimia nervosa: role of glucose and insulin. Int J Eat Disord. 1994;15(4):331-41
6. Dalvit-McPhillips S. A dietary approach to bulimia treatment Physiol Behav. 1984;33(5):769-75