Interviewer: Doctor, you touched on calorie restriction already. What about that is important in longevity? Why does reducing equal potentially a longer life?
Terry Grossman, M.D.: We don't exactly know why reducing calories, but we do know that no matter what species of animal we look at, whether it's a yeast or a fruit fly or a mouse, they will live longer if we restrict their calories. And then if we move closer to human beings, if we get to dogs and monkeys and chimpanzees and apes, which are quite similar to humans, if we restrict their calories, they will live longer as well.
We haven't done any human experiments in term of longevity, because we haven't been doing caloric restriction long enough to know, and humans have such a long life expectancy. We haven't been able to prove that this will work in humans or not, but we have done some studies and we know that, for instance, in youth there are certain genes that are turned on and certain genes that are turned off; and as an individual ages, these things flip flop, and these are aging genes. Well with caloric restriction, we know that it kind of turns back the clock, such that the genes that are turned on are more similar to a more youthful individual, etc. So caloric restriction works as a very effective aging and longevity strategy. Not only do animals live longer when they do caloric restriction, they appear younger and they behave younger.
Interviewer: To get the benefits of caloric restriction, what kind of numbers are you talking about? Do you do a percentage of calories? Do you have a number you shoot for between males and females?
Terry Grossman, M.D.: Well you can take what number of calories you would normally eat and in most of the experiments, they will cut the calories by about 30, or 35-40%. The average in the studies is about 35%. So for someone who is eating 2000 calories a day, this means dropping a third down to about 1300 or 1400 calories per day, which would make an individual very thin, and that's typically how it's done.
In Japan there's a common form of grace before meals that they will say, particularly in Okinawa; and it's three Japanese words, "hara hachi bu," which is Japanese for "stomach eight parts full." And part of the culture in Japan and Okinawa is get up from the table before you've really filled yourself up. So maybe eat until you're 80% full, which we might say corresponds to 20% caloric restriction. And in Japan, the people there have among the highest longevity of any people on Earth. If we look at Japan itself, at the prefecture of Okinawa where they tend to do more of this hara hachi bu, they have the longest life expectancy throughout all of Japan. So there is some suggestion that doing caloric restriction at the degree of about 20% can also translate into increased longevity.
Interviewer: How important is it when you're going to try caloric restriction to make sure that the calories you do get are full of nutrients? I mean, you've got to make those calories count, don't you? Otherwise you could really be starving yourself.
Terry Grossman, M.D.: Absolutely. If you're going to cut your calories, the group that practices calorie restriction are called cronies. That's an abbreviation for caloric restriction with optimal nutrition. Because if you're going to slash your calories like that every day of the week- then yeah, you could get into trouble if you're not careful to make sure that the body gets the essential vitamins, minerals, proteins, fats, and things like that.