Good points, but I'm afraid that people would perceive me as "smart-alecky" if I responded with those retorts.
I like to say, "I used to think I couldn't, either, but you'd be surprised what you can do when you make your health a priority. And now I actually prefer eating this way."
That opens up the possibility that they might be able to do more than they thought they could. Gets them thinking.
The most effective health-care is self-care.
Nutrition is the prescription.
You can literally stretch your lifespan by shrinking your waistline.
Nutrition and other lifestyle factors that you can choose are a more significant determinant of your health than genetics.
Filling your stomach with high-nutrient foods is like by-pass surgery without the surgery.
We are all born with an innate desire to not only survive but thrive.