Is dieting necessary for weight loss?

No: But learning proper nutrition for the rest of you life is. Otherwise, it's 3500 calories to the pound, which means if you don't improve your nutrition, you have to walk 35 miles to lose each pound of excess weight.

No: Eating healthy with fresh fruits, vegetables, whole grains, meat chicken fish, legumes,dairy,beans, nuts and seeds in portion control is the best way to lose weight. Activity daily should also be incorporated into a healthy weight balance program.

Depends on: What definition you use for "dieting". In reality, you'll need to optimize your diet, which means portion control(and thus calorie control - which some will say is "dieting") and choosing healthy food stuffs(like colorful veggies, fruits, lean proteins and healthy fats).

Weight loss: It is not necessary to diet. It is essential to maintain a negative calorie palace by exercising and having the right kind of food. If you burn more than you eat , you will loose weight. It is more about kind of food you eat than quantity of food.