In the nineteenth and early twentieth centuries, prison medical staff in England experimented with diet to understand the relationship between food, behaviour, and health of a population that was either employed at hard labour or sedentary in a single cell. Medical staff further adjusted the diets of inmates to curb violent behaviour and promote mindfulness. Inmates responded, writing to the prison service in personal memoirs about off-putting food options and its impact on culture and mental wellbeing in the institution. This paper considers concepts of control and management in relation to prison diets in England at the turn of the twentieth century, from the perspective of prison administrations and the prisoners themselves. Using case examples from the nineteenth and twentieth century, this paper details how medical and prison officials struggled to recognise, and balance, diet and food provision in the English prison system.