What's a good healthy way to slim down? What's a good diet that will help me?

[Cicero]

So I need a diet that will help me to slim down, combined with my weekly workouts (3x a week I workout) each workout burns about 600 calories, so combined with everything I burn 2100 calories by living and breathing, working out, and by doing daily tasks. I have malnutrition so I'll take vitamins to fill in the missing nutrients.