You want the directions to the Fountain of Youth, hm? That has been an obsession of humans probably since we stopped being hunter-gatherers and had enough time to sit around and think about it. There is no magic formula for living a long life. Some of that is pre-determined for you by your genes. For the sake of discussion, we'll say a very long life is over 100 years, a cool, even century. Reaching an age over 100+ years tends to run in families, and it's common for centenarians to have a sibling (or several siblings) over 100 years old, too. They are winners of the genetic lottery, and oddly enough people who live to be that old tend to be fairly healthy for their age (a still-sharp mind, mostly independent mobility, and few serious chronic conditions). What about the rest of us, dealt a normal hand by our genes?
First, let's talk about why we age. Time is cruel. The little pockets of progenitor cells that renew our body's cells (think skin, intestinal linings, brain, etc.) run out, and the rate of renewal slows. Our cells accumulate DNA mutations over time (see my post about why we get cancer). Cellular respiration, the process of burning fuel using oxygen, generates free radicals which also damages our cells. UV radiation from the sun takes its toll. Slowly, the telomeres (little caps of DNA on the ends of each of our chromosomes) shorten with each cell division, whittling down our life span like sand trickling through an hourglass. We can slow the process, though.
Researchers have discovered that these habits increase lifespan:
1. Exercising. Regular exercisers live longer, perhaps even decades longer than their peers.
2. Avoiding smoking and excessive drinking.
3. Staying active and social, surrounding ourselves with friends and family (the current thinking is that this lowers stress hormones and helps us through tough times).
4. Not eating too much, and eating mostly healthy food.
5. Not being chronically sleep-deprived.
The longest-lived people in the world are a population of short, petite people living on a Japanese island. They live their lives with severe calorie restriction, and severe calorie restriction (we're talking maybe 1200 calories a day here, or less) has been shown to dramatically increase life span in lab rats, and correlates with human life span too. Actually, this may be the single best way to live a very long time: eat only enough to barely stay alive. These long-lived Japanese folks exercise a lot (they still farm, and get around by bicycling and walking) and eat mostly vegetables, fish, and rice. Great foods for long life include fish, green vegetables, olive oil, beans, and eating a mostly plant-based diet. There are communities of people following this diet now, dedicated to living as long as possible.
The Science Lady wonders: is it worth living a long time if you have to barely eat anything and never drink too much? The Science Lady will stick to the more moderate steps 1-4 above, and hope that her genetic lottery number comes up.