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EFFECTS OF WEIGHT LOSS, WAIST AND HIP CIRCUMFERENCE, ALCOHOL INTAKE, AND SMOKING HABITS ON ALL-CAUSE MORTALITY

 

JANE NAUTRUP ØSTERGAARD

Summary

Much research has been focused on the beneficial effects of physical activity. However, the modifyingeffects of physical activity are relatively unexplored but relevant in understanding the health effects ofphysical activity. Physical activity is essential for the body and can prevent diseases from occurring orreduce the development of an already diagnosed illness. Physical activity can most likely reduce therisk of becoming overweight and of regaining weight after a weight loss. In addition, physical activityinduces favourable changes in body composition and fat distribution and may in itself be beneficial tothe circulatory system. The mortality associated with body composition and behavioural risk factors islikely to be different depending on physical activity. The main objective of this thesis was toinvestigate whether the mortality associated with weight loss, waist and hip circumference, alcoholintake, and smoking habits differs between those who are active and those who are not.Worldwide, millions of overweight persons are trying to lose weight. Our findings suggest that evenif weight loss in most observational studies seems associated with increased rather than reducedmortality, this could be a consequence of physical inactivity. We found that physical activity in relationto weight loss is important to prevent premature death among those who are overweight. Further,physical inactivity seemed to attenuate the effects of waist circumference on mortality. A small waistcircumference seems to be related to longevity only for physically active persons, whereas thephysically inactive had high mortality regardless of waist circumference, especially among men. Incontrast, physical activity seemed to counterbalance the effects of a small hip circumference onmortality. A small hip circumference appeared to be hazardous for physically inactive persons,whereas the physically active were not influenced by hip circumference. Furthermore, physical activitycould not compensate for a moderate alcohol intake in prevention of early mortality. Both a moderatealcohol intake and physical activity were important to lower the risk of fatal IHD and all-causemortality. Finally, physical activity could not counterbalance the hazardous effects of smoking. Bothphysical activity and healthy smoking habits seemed important for longevity. When being physicallyinactive and a current smoker, it seemed more important for survival to stop smoking, especially forwomen. Thus physical activity seemed to modify the mortality associated with weight loss and waistand hip circumference, whereas physical activity did not modify the mortality associated with weeklyalcohol intake and smoking habits. These results have implications both for public health messages on,and for future studies of, biological mechanisms regarding physical activity, in particular, and alsoweight loss, waist and hip circumference, alcohol intake, and smoking habits.In conclusion, physical activity is important for preventing cardiovascular disease and early death.In addition, our studies also show that the mortality associated with weight loss and waist and hipcircumference is dependent on physical activity, but that the mortality associated with weekly alcoholintake and smoking habits is independent of physical activity. From a public health perspective, ourstudies support earlier evidence of the importance of physical activity in preventing excess mortality.