The current study assessed the views and attitudes of health professionals (HPs) regarding factors associated with energy balance-related health behaviours and weight management in breast cancer survivors (BCS) with overweight and obesity. Semi-structured online interviews were conducted with 21 HPs (oncologists, dietitians- nutritionists, physical education instructors, mental health professionals, and nurses) from Attica and Thessaly. Thematic analysis was used to analyse and present the data. Four main themes arose from the data: "The patients' mental health wellbeing", "Survivors' interest in diet and exercise", "Interdisciplinary collaboration in patient's care", and "Maintaining normality". HPs agreed that weight loss in BCS with overweight and obesity is important, but negative mental health wellbeing is a main barrier to behaviour change. For many BCS their cancer diagnosis is a "teachable" moment for weight management, especially for women of younger age, who are more keen to discuss weight management issues. Essential characteristics that determine/facilitate behavioural change include education, commitment for regular communication, personalised intervention, and interdisciplinary collaboration. According to HPs, future weight loss interventions should take into account BCS's mental health wellbeing and level of motivation and should provide regular support and education.