Biological Factors


Biological Factors

 

Set Point Theory

Biologically, every individual will maintain their body weight within a certain range after they grow up. Therefore, when we use irrational means (such as extremely low calories intake) and extremely high speed to lose weight which our body cannot adapt to, his/her metabolic rate will slow down in order to regulate the body weight to retrieve the set point [23]. If we cannot gradually teach our body that the reduced pounds or fat are not necessary for our body, our body will try its best to store fat in order to maintain the set point (the pounds). These can explain why people who reduce weight in a short period of time will usually rebound when they eat normally. This theory explains why people who adopt extreme dieting methods usually have a very strong desire to eat both psychologically and physically, and thus explain why losing weight too speedily would precipitate weight rebound sooner or later.

 

Dysfunction of Serotonin

Many studies showed that the abnormalities (such as inactive) of serotonin were associated with the development of eating disorders [24]. In addition, many patients have comorbidity with illnesses related to the problem of serotonin, such as Anxiety Disorders, Obsessive Compulsive Disorders and Mood Disorders [25]. Drugs, like Selective Serotonin Re-uptake Inhibitors (SSRIs) may help patients stabilize their emotions and as a result would proceed to stabilize their modes of eating. However, it is not effective for anorexic patients due to disorders of their biological systems. The drugs may be effective only if they restore to normal weight [26].

 

Genetic Factors

In family studies [27], higher incident rates of eating disorders among relatives of eating disorders patients were revealed. Besides, in twins studies, monozygotic twins had higher concordance rate of eating disorders than dizygotic twins, which showed that genetic effects had been in association with the development of eating disorders. However, such high concordance rate might be attributed by both the shared genes and the shared environment.

 

Hormonal Change

According to some studies, the ratio of female to male in prevalence of eating disorders was approximately 10:1 [28], of which adolescents and early adults were regarded as the high risk population. The greater possibility of developing eating disorders in these periods most probably was related to the hormonal [29] and physical changes [30] (being taller, the development of secondary sexuality) of adolescents during puberty.

 

ReferencesÔľö
[23]Keesey, R. E. (1995). A set-point model of body weight regulation. In K. D. Brownell & C. G. Fairburn (Eds.), Eating disorders and obesity: A comprehensive handbook, pp.46-50. New York: Guilford.

[24]Jacobi, C., Hayward, C., de Zwaan, M., Kraemer, H.C., Agras, W. S. (2004). Coming to terms with risk factors for Eating Disorders: Application of risk terminology and suggestions for a general taxonomy. Psychological Bulletin, 130(1), 19-65.

[25]Steiger, H., Young, S. N., Kin, N.M.K., Ng, Y., Koerner, N., Israel, M., Lageix, P., Paris, J. (2001). Implications of impulsive and affective symptoms for serotonin function in bulimia nervosa. Psychological Medicine, 31(1), 85-95.

[26]Favaro, A., Tenconi, E., Santonastaso, P. (2006). Perinatal factors and the risk of developing Anorexia Nervosa and Bulimia Nervosa. Arch Gen Psychiatry, 63, 82-88.

[27]Jacobi, C., Hayward, C., de Zwaan, M., Kraemer, H.C., Agras, W. S. (2004). Coming to terms with risk factors for Eating Disorders: Application of risk terminology and suggestions for a general taxonomy. Psychological Bulletin, 130(1), 19-65.

[28]Jacobi, C., Hayward, C., de Zwaan, M., Kraemer, H.C., Agras, W.S. (2004). Coming to terms with risk factors for Eating Disorders: Application of risk terminology and suggestions for a general taxonomy. Psychological Bulletin, 130(1), 19-65.

[29]Garfinkel, P. E., & Garner, D. M. (1982). Anorexia nervosa: A multidimensional perspective. New York: Basic Books.

[30]Coovert, D. L., Kinder, B. N., & Thompson, J. K. (1989). The psychosexual aspects of anorexia nervosa and bulimia nervosa: A review of the literature. Clinical Psychology Review, 9,169-180.