You are absolutely right. Exercising while being fat is hard on the joints; really, water workouts and stretching are the only truly safe ways for a morbidly obese person to exercise. Also from a psychological standpoint, fixing diet first and exercise later will increase their chances of success, because once a person has successfully changed one major habit, all other habit changes are statistically significantly more likely to be achieved. But what do fatties do? Skip breakfast, eat a stupid chocolate granola bar for lunch, eat 5000kcals in one sitting for dinner, gain weight, and reee about diets not working. sigh