Author	S.E. Jackson
Author	A. Steptoe
Author	J. Wardle
Author	R.J. Beeken
Abstract	The prevalence of obesity has reached dramatic proportions over recent years, and obesity among older adults is becoming an increasingly important concern in developed countries with ageing populations. Weight loss is recommended for all obese individuals, regardless of age, yet while there has been a vast amount of research into factors surrounding weight loss across younger and middle-aged populations, the evidence base on weight loss in older adults is lacking. This thesis uses data from a cross-sectional survey of UK adults, and two large epidemiological studies of ageing, the English Longitudinal Study of Ageing and the Health and Retirement Study in the US, to address this gap in the literature. Study 1 highlights the high prevalence of desire to weigh less and attempts at weight loss among older adults, and Study 2 reveals that a surprisingly high proportion of those who are overweight or obese are achieving clinically meaningful (≥5%) weight loss. Studies 3 and 4 show that despite reductions in cardio-metabolic risk, weight loss in overweight/obese older adults is associated with increased risk of depressed mood, and this association grows stronger with each decade of age. However, Study 5 finds some evidence to suggest that rates of depressed mood might only be increased during the process of weight loss, and that if weight loss is maintained there might be benefits for mood relative to baseline. This research contributes to the understanding of weight loss in older adults - particularly that which occurs in the general population, outside of the trial context - and emphasises the need for health professionals to take into consideration patients' psychological wellbeing when recommending or responding to weight loss at older ages. Limitations of this work and directions for future research are discussed.