Background Brazil has seen a large increase in obesity with 54% of the Brazilian population being overweight, of which 20% is obese. Obesity is a major risk factor for non-communicable diseases such as cardiovascular disease: the leading cause of mortality in Brazil. Weight loss can reduce the health and economic burden of obesity-related diseases. Despite many weight loss strategies, the obesity rate in Brazil remains high. This study aims to identify the barriers and facilitators to weight loss as perceived by patients with a view to reducing the burden of obesity-related diseases on patients and healthcare services.Methods Fifteen qualitative, semi-structured, in-depth interviews were conducted with the primary researcher in the preventive medicine department in a private health clinic in Bauru, Sao Paulo State, Southeast Brazil. Inductive thematic analysis was conducted.Results Barriers and facilitators were classified into three key themes: lifestyle, motivation and education. Barriers included the expensive cost of a healthy lifestyle, junk food advertising, risks of outdoor exercise, time restrictions, poor mental health, sleep deprivation, medication side-effects, misinformation and lack of accessibility to weight loss treatment through the public healthcare system. Facilitators to weight loss included a change in eating habits, packed meals, documenting eating habits, motivation from consequences of obesity, acceptance of a lifelong commitment, support from social capital, psychologists in the multidisciplinary team, financial support and good quality education, particularly the use of expert patients as educators.Conclusion The study contributes to the existing literature on obesity in Brazil. Barriers to a healthy lifestyle such as financial difficulties, accessibility to treatment and junk food advertising need to be addressed. Education is vital to promote the facilitators and target these barriers and dispelling myths on weight loss. Expert patients should be utilised as an education method, as they increase motivation and provide realistic expectations of the weight loss process.