Background: Obesity is now one of the most important public health issues in Saudi Arabia, with 74.2% of women and 69% of men found to be overweight or obese, but there is limited research into the nature and effectiveness of overweight and obesity management in primary care in Saudi Arabia or elsewhere. International literature supports the role of primary health care in managing obesity through evidence-based interventions, yet also notes many barriers to health professionals helping patients achieve significant weight loss. A new collaborative and patient-centred approach to primary care management of chronic disease, Fit and Minimally Disruptive Medicine, appears potentially well-suited to helping patients manage their weight. Research Aims: This thesis aimed to determine health professionals’ and patients’ views on the appropriateness and quality of current obesity management practices in primary health care in Riyadh, Saudi Arabia., and also their views on the acceptability, utility and applicability of Fit and Minimally Disruptive Medicine to assist successful weight management. Research Methods: Preliminary informal interviews were held with representatives of key groups in primary health care in Riyadh, four senior primary health care officials, 10 primary health care centre managers, 20 doctors, 20 nurses and 20 patients from 10 primary health care centres. The main investigation used the interview material to develop two structured questionnaire surveys for a quantitative cross-sectional descriptive study on the management of overweight and obesity in primary health care. The first questionnaire, for doctors and nurses, addressed primary health care centre resources and services, use of weight loss strategies, and the health professionals’ views on overweight and obese patients, obesity management and the Fit and Minimally Disruptive Medicine approach. The second survey, for patients, addressed patients’ motivation and readiness to lose weight, support from family and friends, weight loss options used, satisfaction with services provided by their primary health care centre, and views on using the Fit and Minimally Disruptive Medicine approach. The surveys were conducted in iv 53 primary health care centres in four out of five health sectors in Riyadh City; 10 centres were included in a pilot study and 43 in the main study. The main study was conducted with a sample of 77 doctors, 78 nurses and 80 patients. Results: Findings showed that while primary care practice management of obesity in Riyadh incorporates some best practice recommendations, there are important elements that are rarely, or inconsistently, used. Only 44.2% of doctors and 55.1% of nurses, for example, always calculated patients’ body mass index, and only 10.4% of doctors and 12.8% of nurses always assessed the patient’s progress for more than six months. The main strategy for obesity management was the recommended combination of diet, exercise and behaviour modification (67.5% of doctors and 56.4% of nurses). Reported barriers to establishing obesity clinics included inadequate resources, and administrative and referral issues. The patient survey found 90% of patients said they were ready to lose weight, but identified various barriers, including lack of family and friend support, and dissatisfaction with their primary care centre’s staff and services (48%). The majority of health professionals and patients supported the use of Fit and Minimally Disruptive Medicine weight management. Discussion: This thesis makes a major contribution to the literature on the effectiveness of primary care management of obesity, notably including the patient perspectives. The thesis is also the first to investigate health professionals’ and patients’ views on applying Fit and Minimally Disruptive Medicine to weight management. Recommendations for Saudi Arabia include further training of health professionals, the introduction of clinical practice guidelines on managing obesity, and a pilot study of using Fit and Minimally Disruptive Medicine for weight management in primary health care. This thesis provides valuable guidance for health care organisations seeking to improve the management of overweight and obesity in primary care, and for researchers interested in undertaking further investigations in this area.