Text in English / In order to address the paucity of knowledge in regard to the psychological and physiological processes associated with lifelong weight loss (>20 years), this study adopts a qualitative approach informed by phenomenology to explore the experience of lifelong weight loss and maintenance of women who participated in the ITAND Programme. The research questions guiding the exploration of the current research are: (i) Which strategies from the ITAND Programme do women perceive as assisting with initial weight loss? (ii) What are the processes mediating lifelong weight loss? (iii) What strategies and skills mediate the maintenance of lifelong weight loss? (iv) What feelings or beliefs motivate women to continue attempts to lose weight after experiencing multiple failures on diets? and (v) Which psychological, cognitive and behavioural processes are identified as mediating lifelong weight loss? Eight overweight and obese women were invited to write their narratives and engage in interviews in regard to exploring their relationships with food, their bodies and their weight, after a period of more than 20 years following their participation in an integrative, transactional analysis, anti-diet programme (the ITAND Programme). Narratives were used to explore their beliefs about constructs, processes and strategies mediating long-term weight loss maintenance. The participants’ narratives and interviews were analysed through applying narrative analysis and interpretive phenomenological analysis. In addition to a non-diet paradigm, four processes definingweight loss maintenance were identified, including the adult learning process of transformative learning, the psychological process of transactional analysis, the physiological process of intuitive eating and the cognitive-behavioural processes relating to weight loss maintenance. This study contributes an integrative, transactional analysis, non-diet treatment model (ITAND model) which is enabled by the processes of transformative learning, intuitive eating and cognitive-behaviour modification to the successful long- term treatment of overweight and obesity. This model may be applied in whole or in part in a primary health care or community context. The findings of this study may be used to inform future research into the development and implementation of non-diet weight loss maintenance interventions in the treatment of overweight andobesity. / Psychology / D.Litt. et Phil. (Psychology)