Interesting articles, but not a lot to do with dieting. I'm yet to see any scientific argument that links increases in HUMAN metabolism to premature ageing, but it would certainly put a whole new slant on the argument for regular eating and exercise!
From my point of view, people who live a healthy lifestyle, eat properly and exercise regularly (i.e. most likely have a higher metabolism) generally look younger and healthier than those who live a lifestyle much the opposite.

"Never argue with idiots. They'll drag you down to their level, then beat you with experience."