I've always envied people with high metabolism because, well, who wouldn't? I would looove to be able to eat all the pastries I ever want and simply burn it off. For example, I would be able to eat dessert with my regular food instead of eating cake for dinner. I'm only half kidding.
If you would like to live long, having a slow metabolism is better for you. (Meaning, eat less, burn slower, have a lower happiness factor but multiply by longer life span and voila! You'll be less happy but for longer).
In a wide range of organisms including yeast, flies, mice, and primates, calorie restriction has been found to increase life span by up to ~50%. 50%! This process may have been conserved across species because the ability to adapt to environmental stress such as lack of food may be useful. Organisms can then delaying development until the conditions become favorable.
Artificial "starving" situations can be created by restricting calories, and the body WILL respond. Dr. Walford participated in Biosphere 2, an enclosed biosphere project, where the members unable to sustain normal amounts of food, naturally had a restriced diet. The crew members emerging out of the biosphere after 2 years showed improvements in health such as lower blood pressure and cholesterol. He developed the CRON-diet, which recommends consumption of lower calories to maintain a weight about 10~15% lower than their stable "set point" weight.
The effects of CR diets in humans remain controversial as it has been shown to have mixed effects. CR dieters show improved memory, lower blood pressure, lower triglyceride levels, but may develop eating disorders because well, they're literally being starved.
(Read the NY magazine article of a reporter's attempt at CR diet here).
So what is the actual mechanism behind longevity through CR? In rodents, yeast and company, SIR2, a histone deacetylase has been suggested to mediate this life extension. SIR2 may control further endocrine signaling and DNA repair mechanisms such as p53 and FOXO which increase stress resistance and promote longevity. (Read all about it in this Cell review).
It's definitely not for me. The world is full of too many delicious things for me to give them up. Besides, CR hasn't been proven to completely to have only positive effects, right? So... until then, I'm going to eat my foods, like this from Koriente in Austin:
Mmmmmmm, as I'm sipping my black coffee. It's National Coffee Day today!