I have had many people over the years come to me wanting to lose 20-30lbs. Often times these people claim to "eat healthy" yet they're 20lbs overweight. If you're 20lbs overweight then you're not eating healthy. It does not matter whether you have organic, non-gmo foods, or special olive oil imported from overseas. If you're 20lbs overweight you're not eating a healthy diet.
With that said, eating healthy and fat loss dieting are not necessarily one in the same. One should not be in a permanent calorie deficit. Consuming food that maintains a healthy weight is better than a diet that has you 20lbs overweight.
Eating to lose weight is literally eating less than you're supposed to. This is not a good long term plan but can be strategically done in phases. Dropping about 10% of your bodyweight then eating at "maintenance" for about as long as it took you to lose the 10% is a solid gameplan.