You realize of course that choosing that weight lose is the most important metric is just another form of rationalization. If you take a step back to first principles and start with a reasonable goal such as "I want to feel better and live longer" then zeroing in on losing weight is not necessarily the most effective path. For obese people it might be, but for normal people getting regular exercise and eating right (which varies by individual) will have a much more positive effect than obsessing over weight.
Furthermore, telling people to count calories and not worry about the quality of what they eat is just opening the door for that same destructive human behavior of eating whatever crap they want, just in limited quantities. This is not the road to health. No amount of engineering mentality will get around the fuzziness of health or the stubbornness of human nature. Fortunately people are capable of being honest with themselves to varying degrees, and it is possible to improve one's health by a commitment to exercise and healthy eating.
Furthermore, telling people to count calories and not worry about the quality of what they eat is just opening the door for that same destructive human behavior of eating whatever crap they want, just in limited quantities. This is not the road to health. No amount of engineering mentality will get around the fuzziness of health or the stubbornness of human nature. Fortunately people are capable of being honest with themselves to varying degrees, and it is possible to improve one's health by a commitment to exercise and healthy eating.