B1 [C or U] the food and drink usually eaten or drunk by a person or group: Diet varies between different countries in the world. a healthy/balanced/varied diet Rice is the staple diet (= most important food) of many people in China. The children seem to exist on a diet of burgers and chips.Diets and dieting B1 [C] an eating plan in which someone eats less food, or only particular types of food, because they want to become thinner or for medical reasons: I'm going on a diet next week and hope to lose ten pounds before Christmas. a crash/strict/calorie-controlled diet The doctor put me on a low-salt diet to reduce my blood pressure.Diets and dieting › [S] a particular type of thing that you experience or do regularly, or a limited range of activities: He was brought up on a diet of political propaganda from birth. The TV only offers a diet of comedies and old movies every evening.Standard and routineHabitual behaviour