Michelle;
everyone is different. On one person, an extra 50 lbs might barely be noticeable to look at, and that person may be active and feel good all the time; while on another, that extra fifty is enough to destroy their health and make them look very obese. So one can't really answer that without allowing for all the variables. As for what makes someone "healthy"; this too varies. a person confined to a wheelchair will have a different standard of health than someone   who is ambulatory. But in general, most doctors would agree that having your blood pressure, heart rate and cholesterol within the normal range for your height and weight is a start, and most obese people do not have this. To me personally, a healthy person is one without chronic pain or illness, emotionally stable, who feels they have a purpose in life and who looks forward to each day.

And I did not say ten minutes on the stairs; I said one flight of stairs, or ten minutes of walking: big difference there. If you are going to challenge my words, at least try to quote them correctly.