If you continually diet you are putting your body in a quasi-famine situation. It slows your metabolism down and breaks the thermostat. Diets don't work. They don't help you understand why you're eating more than your body wanted in the first place.
The Word of God well understood and religiously obeyed is the shortest route to spiritual perfection. And we must not select a few favorite passages to the exclusion of others. Nothing less than a whole Bible can make a whole Christian.