To believe that a slow metabolism promotes longevity is embracing a fallacy that when our cells have too much energy to process they just shut down or become resistant. It's not true, energy and structure are interdependent at every level, when you have the ability to do something, you do it.
This is why metabolism and intelligence go hand in hand.
Q: How malleable is human intelligence?
Ray: "In 1962 Mark Rosenzweig showed that an enriched environment caused rats' brains to grow. A little later, someone found that the DNA content of human brains kept increasing until the age of 90, and about 10 years ago, studies started showing experience-related growth in human brains. Thyroid and thiamine can have great effects on mental ability, and the steroids can either shrink or expand the brain substance. The old Weissmanist-Hayflick doctrine has kept people from thinking about the adaptive nature of adult tissues, but more people are starting to realize that the principles of embryology keep functioning throughout life."
I take a little thyroid because it gives me clarity, same with coffee. Since expanding my metabolism greatly, I've memorized an absurd amount of knowledge in a short time, and no longer am prone to bouts of horrible brain fog and forgetfulness.
Time is passing so quickly. Right now, I feel like complaining to Einstein. Whether time is slow or fast depends on perception. Relativity theory is so romantic. And so sad.