Let's Get Healthy To Lose Weight

Do you agree that you must be healthy to lose weight than losing weight to be healthy? Some people believe that you must lose weight first in order to get healthy enough to have the energy and endurance for a healthy and prosperous lifestyle. Yet there are other who strongly support getting healthy enough first then work on losing weight. Which one is best? Could 99% of people who exercise unknowingly damage their thyroid and metabolism and be setting themselves up for long term weight gain?