WHere is that quote from.
If you want to go on a strict diet it will help, and is a good idea, but a strict diet isn't necessary if you're already pretty overweight and consume a lot of refined sugars/carbs, oils. Just reducing those and eating healthier will automatically get you lean.
Calories in, Calories out. Your body doesn't burn fat unless it needs to for energy. Has nothing to do with how "healthy" your foods are.
So you're saying what you eat, considering the calories are the same, doesn't matter? What about hormones? Like insulin?
You're basically saying "hey if you eat 2500 kcal of sugar or 2500 kcal of good healthy foods per day will do the same thing for your body fat %, body composition, strength etc"? It's not that easy.