Is a Higher Metabolism always a Good Thing?

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Everyone on this site wants the highest metabolism possible to lose weight. That's great! It's like free calories--calories you burn without actually going to the gym. But is it really a necessary goal for weight loss?

In trying to calculate my numbers accurately, I've come across several studies that have shown that people with lower metabolisms actually live longer: http://www.huffingtonpost.com/joel-fuhrman-md/metabolism-aging_b_870845.html.

What do you think? Reading this (and other similar articles) make me thing of a LOT of people I know who have never had weight issues. I know a lot of women who eat around 1500 calories a day, every day, and don't loose or gain weight at that (it's just what they've always eaten). That would put them at a low metabolism according to this site. Should the normal size people be trying to raise it? Or should people who want to lose weight on this site just accept whatever their metabolism is and try to eat a healthy diet within that range?