1 the process of eating less in order to lose weight -- régime [ masculine ]
I’m going on a diet. Je commence un régime.
2 to eat less in order to lose weight -- faire (un) régime
people who diet without exercising les personnes qui font un régime sans faire d’exercice
3 food, especially a course of recommended foods, for losing weight or as treatment for an illness etc -- régime
4 to eat certain kinds of food to lose weight -- suivre un régime