Thesis title: Health Professional-patient communication in relation to weight managementBackground: Global obesity levels have doubled since 1980 and are expected to rise. It is associated with key health risks such as heart disease, some cancers and osteoarthritis and hence has considerable economic consequences for health care resources. Key policy guidelines recommend that all health professionals (HPs) should discuss weight management with their patients making every contact count. However, we know HPs find discussions about weight challenging due to lack of time, training and skills. Knee Osteoarthritis (KO) and obesity are inextricably linked and together with a rise in obesity levels and growing numbers of older citizens rates of KO are set to escalate. As obesity is the key modifiable risk factor for KO, discussions about weight are paramount. This thesis explored this relationship further from the perspectives of patient and HPs, focusing on KO as an exemplar condition where there is scope for improved weight management.Methods: Utilising qualitative methods, three studies were undertaken. Firstly, a systematic review and thematic synthesis was conducted of published literature of physicians' views and experiences of discussing weight management within routine clinical consultations, not specific to KO. Secondly, HPs' experiences of discussing weight in consultations with KO patients through semi-structured interviews were conducted with 26 HPs. Interviews were audio recorded and analysed using TA. A final study recruited 25 overweight/obese patients with KO and investigated their experiences of talking about weight with HPs. Results: Overarching themes were identified across the studies. Firstly, HPs are pessimistic about patients' desire to lose weight and their capacity to help them. Several factors lead physicians and HPs to be reticent to accept responsibility for discussions about weight. Within routine consultations and between HPs and KO patients, weight was viewed as a sensitive topic. Both HPs and patients recognized the difficult cycle of pain, reduced mobility and weight gain. Patients with KO desire patient-centred (PC) care but, despite HPs recognizing its value, they do not receive it. Both physicians and HPs lack communication skills in weight management. Conclusions: The work undertaken in this thesis demonstrates that barriers preventing effective clinical interactions about weight identified in routine consultations still exist, even when two conditions such as KO and obesity are inextricably linked. Although HPs and patients hold similar understanding of these interrelationships and recognise the value of PC discussions, HPs struggle in effective behavior change talk. HPs expressed impatience with the efforts of their patients. To readdress this imbalance all consultations about weight should be PC. Both physicians and HPs were inadequately trained to discuss weight and patients' views supported this. HPs working with overweight patients should be trained in evidence-based behaviour change techniques and PC communication techniques to increase their confidence to support patients in weight management. Finally, health psychologists have the skills to both deliver and guide discussions about weight.