If they do, they have the power to tell us how to live our lives. What to eat, what to drive, where we live, what bulbs we use, what appliances we use, what the temperature we live in, what schools to go to, what subjects we take, what careers we'll have, how many children we can have, what surgeries we'll be allowed, what medicine they allow, what doctor to see, what hospitals we use, what trees we can cut, what trees we can plant, how much water we can use, when we can use it, what we can throw in the trash, what we must recycle, what color our roofs are..........see...
this is where we are headed when we start trying to control a person's diet.
If you can control what a person eats you can control any aspect of their lives.
Until there is a real cure for obesity, people have a right to be as big as a bus, just as gays are allowed to have gay sex that may lead to AIDs though we have no cure or as people are allowed to over indulge in alcohol or any number of dangerous behaviors.