The use of androgen deprivation therapy (ADT) has coincided with improvements in disease control and improved overall survivorship in many men treated for prostate cancer. Exercise and nutrition interventions during and/or after ADT are strongly recommended to mitigate or improve body composition and reduce cardiometabolic side effects. The aim of this study was to examine the combined effects of a Mediterranean diet (MED-diet) and high intensity interval training (HIIT) on cardiorespiratory fitness, body composition and quality of life, compared to usual care, in men with prostate cancer treated with ADT. This study is a two-arm randomised controlled trial. Participants (n = 23) were randomly allocated to either an intervention or usual care group in a 1:1 ratio. Results show that for men with prostate cancer undergoing ADT, a MED-diet with HIIT compared to usual care at 20 weeks (i) significantly improved cardiorespiratory fitness relative; (ii) reduced body weight; (iii) maintained lean body mass despite achieving weight loss; (iv) significantly improved vitality and mental health composite, and clinical improvements were seen in prostate-cancer specific quality of life and cancer-related fatigue. Authors conclude that future larger-scale trials examining the MED-diet with HIIT on cardiorespiratory fitness, body composition and quality of life would help to extend the findings of their study.