"Dieting" describes any process of tracking and restricting your diet. For instance, I have type 1 diabetes, so I'm on a diet worked out together with my clinical dietician, which is separate from any weight loss issues. Eating vegeterian, eating healthy, etc. are all diets.

Secondly, when dieting to lose weight, you normally eat as many calories as you need - not less. You'll lose weight as long as you stop eating more than you need to get to your target weight.