Doctors do not only tolerate a treat here and there, they encourage it. McFadden, 101, eats chocolate chip cookies and likes red wine and Bloody Marys. Viola Crowson, 101, sometimes bakes brownies or grabs a hamburger from Hardee's. David Prince, M.D., says sugar and red meat should be limited to once or twice a week but can be eaten if portions are small. More From Forbes: America’s Healthiest Cities World’s Most Dangerous Places to Breathe The ‘Healthy’ Choices That Are Costing You The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.