Familial and non-familial factors associated with obesity

Abu-Rmeileh, Niveen Mohammad Elias (2003) Familial and non-familial factors associated with obesity. PhD thesis, University of Glasgow.

Abstract

The work of my thesis is based on the MIDSPAN Family Study, which included a survey of the parent generation in 1972-6 and the offspring generation in 1996. The main aim was to investigate familial and non-familial factors associated with changes in body mass index (BMI) between the two generations and to identify the characteristics of susceptible subgroups. The study populations come from a highly deprived area with high mortality and cancer incidence rates. In the parent population, BMI was positively associated with cardiovascular mortality and negatively associated with respiratory mortality. Only breast cancer and lung cancer incidences were associated with BMI. Lung cancer incidence was negatively associated with high BMI. The observed association was not the result of confounding effect of smoking or sub-clinical illness. The negative association between lung cancer incidence and BMI was found in other cohort screened at the same time as the parents cohort. This finding encourages further research explaining this observation at the biological level. The first finding was that the prevalence of obesity (BMI>30kg/m2) has doubled in sons while a slight increase in the prevalence of obesity was found in daughters with almost no change in mean BMI or the prevalence of obesity and overweight combined (BMI>25kg/m2). Comparison of BMI distributions in parents and offspring showed an anchoring of the lower parts of the BMI distributions and skewing in the top parts. To a certain extent this observation was found in all social class and smoking subgroups. Parental obesity was the strongest factor associated with offspring BMI and obesity prevalence. The offspring of obese parents were more than four times as likely to be obese than the offspring of lean parents. Physical activity, smoking status and dietary intakes were the important environmental determinants of high BMI. However, the effect of these factors was not the same in men and women or in different social class groups. Further, the correlates of high BMI were different in offspring with and without family predisposition to high BMI. Familial susceptibility is an important factor associated with offspring obesity. The offspring of obese parents are at highest risk of becoming obese themselves. However, the effect of familial susceptibility depends on environmental and behavioural factors. This conclusion was based on findings from studying exceptions (obese offspring with obese parents and obese offspring with normal weight parents) and differences between groups of offspring (obese and normal weight offspring of obese parents and obese and normal weight offspring of normal weight parents) offspring groups. In the presence of family susceptibility, obese offspring were less likely to be smokers, to be in the manual social class and were less physically active than normal weight offspring. In the absence of family susceptibility, obese offspring were more likely to be former smokers, to be in the manual social class, were less physically active and reported high intakes of energy-dense foods than normal weight offspring. On the other hand, obese offspring with family susceptibility were more likely to be smokers, in the manual social class, physically active and had high food intakes compared to obese offspring without family susceptibility. Normal weight offspring with obese parents were more likely to be smokers, in the manual social and to report high food intakes. The findings of this study are consistent with gene-environment interaction in the development of obesity and stress the fact that offspring with family susceptibility are more affected by differences in environmental and lifestyle factors. Individuals with familial susceptibility to obesity are at higher risk of becoming obese if they are former smokers, in the manual social class and physically inactive. They are less likely to become obese if they are current smokers or have manual father. The findings encourage further research to investigate the genetic and patho-physiological basis of these findings. Furthermore, these findings raise the possibility of intervention programmes targeted at high risk groups.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Public health.
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > General Practice and Primary Care
• Supervisor's Name: Watt, Prof. Graham and Hole, Prof. David
• Date of Award: 2003
• Depositing User: Enlighten Team
• Unique ID: glathesis:2003-41129
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 18 Apr 2019 07:59
• Last Modified: 07 Jun 2021 14:01
• URI: https://theses.gla.ac.uk/id/eprint/41129