Weight is not always a good indicator of health (even though many people make that assumption.) Some of the unhealthiest people I have met are vegetarians, high endurance athletes, and those on high carb diets. I'm not an advocate of no carb... however, I'm firm believer in low carb (around 100-150 grams per day to maintain weight, less than 50 grams per day for weight/fat loss.) I also know that cultures with low carb diets have nearly non-existent rates of diabetes (too late for me.) I don't want to lose weight to get to a number by losing fat, but also losing significant amounts of muscle tissue.
If you, or anyone else is interested, "Primal Blueprint" and marksdailyapple.com have some interesting concepts and theories concerning diet and exercise. Mark, himself, is a former world class endurance athlete and ate the high carb diet that was recommended for him. He indicates that his body was not healthy with the extreme amounts of cardio training and the associated carbohydrate diet. He says that he is healthier at 60 than he was in his 20's and a world class athlete. Anyway, his explanations, theories, and concepts make sense to me and produce results (when I can maintain the program.) There is no question that whatever you do to lose weight, build strength, and improve conditioning is going to require hard work and discipline.