i don't really diet, i once tried eating only veggies at lunch and i gained 1 kg instead.
I think the trick is just eat when you are hungry? but only small portions.
Also try to exercise at least 30 minutes a day.
everyone can be successful with a diet, you need to see a doctor to consult about what diet is suitable, it will be safer, with a doctor adjust your diet,
exercise more regularly and maintain carbohydrate intake