Obesity (BMI ≥30 kg/m²) is associated with a number of chronic health problems such as diabetes, heart disease, hypertension and cancer. Epidemiological data has linked obesity with prostate cancer. The aim of this review is to provide an up to date account of the relationship between obesity and prostate cancer based on scientific research evidence.A search of several databases using key words such as “prostate”, “cancer”, “obesity” and “overweight”, identified a total of 2195 articles. From this, 47 were selected for review, based on the number of citations, impact factor and relevance to the field. Studies published in the past five years were favoured. Two on-going trials were also included for reference.Potential ways in which obesity may affect prostate cancer is via a detection bias, facilitating aggressive tumour growth, poor treatment outcomes and reduced survival rates. The most commonly studied mechanisms underlying obesity and prostate cancer include alterations in the levels of insulin, adipokines and androgen, as well as altered sensitivity and efficacy.Evidence on the potential link between obesity and prostate cancer is conflicting. Many studies indicate the need for further research into the field. Specifically, there is a need for further large-scale multi-centre meta-analyses to triangulate factors affecting prostate cancer and obesity. A proxy measure for obesity that reliably accounts for adiposity is also needed. Overall, although most studies conclude that obesity has a negative impact on health, its effect on prostate cancer progression remains unclear.