If I had to pick one thing that is THE most important factor in human aging that is under our control I would say without hesitation it would be sugar consumption. This is because when you overconsume sugar in the form of carbohydrates, your body releases insulin.
Research on laboratory animals has confirmed that the more insulin you produce in response to carbohydrates in the diet, the faster you will age, and the more health problems you will have.
The famous Baltimore Longitudinal Study of Aging which is an ongoing study of human aging begun in 1958 has tracked 1,400 men and women from age 20-90 to determine the effects of aging over time. This study hasconsistantly found that three things characterize healthy aging and longevity. Those three things are:
higher than average DHEA levels lower than average insulin levels lower than average body temperature
These three factors go hand in hand! The analysis of these results seem to mimic the results of calorie restriction experiments on laboratory animals. However the people in the research study were not on special diets and did not necessarily restrict their calorie intake.
Some researchers have theorized that insulin raises body temperature, and again this seems to correlate with experimental data from the animal studies. If all this science is getting you confused, then take heart, because there is a simple and inescapable conclusion to all this, and that is that reducing theglycemic index of your meals, will help you to live much healthier and longer.
I have written a web page on this topic that you may find interesting.