Raena Morgan: Doctor Roizen, what is the thrifty gene theory about and are you at a metabolic disadvantage if you have it?
Dr. Michael Roizen: Well the thrifty gene is what happens to you in utero or your parents or your grandparents or someone else that change the way you function. What happens is, for example, if you’re pregnant, Raena, and I’m not trying to say you are,-
RM: Okay. I’m not, no.
MR: Okay. We have a new book coming out, You Having a Baby, and I asked Oprah if she wouldn’t try and get pregnant for us so it could launch on the show.
RM: And she said no, categorically.
MR: And she said “I’ll try, but it aint going to happen.” So anyway, but the point is that in utero your child, your baby predicts the future.
MR: So if you didn’t give them enough nourishment, it was a famine for example, they would predict that there was always going to be a famine, and so they would methylate certain of their genes and those genes were ones that shut down your metabolic rate-
MR: -when you can get food for a little bit of time. So the baby predicted at those methylations stay with that family forever, that’s part of the gene pool from then on for that family. So it was a prediction of what the environment was going to be like on the outside.
RM: Which means it would not be enough.
MR: There would not be enough food. They were going to be in a famine mood, so they would shut down their metabolic rate so they could survive a famine without causing great damage to them. So what it is is we change genes over thirty thousand years, meaning long periods of time, but we change expression of genes whether they’re on or not what we can epigenetics very quickly during a pregnancy.
MR: But those epigenetic changes stay with your kids and your grandkids and their grandkids et cetera, and that’s how we’re able to adapt to famines and other things relatively quickly; it actually comes through the pregnancy prediction by the child. Well about someplace around sixty percent of Americans have a thrifty gene passed on through on generation or another.
MR: Okay. So when you’re- so you would have had a disadvantage compared to the other forty percent, but it’s nothing you can’t control.
RM: That’s what I wanted to hear.
MR: All it means is when you don’t get food for eight or twelve hours you shut down your genotype or you tend to store fat. Well that’s a good thing if you’re-
RM: In a famine.
MR: -in a famine. We don’t have many famines now in America,-
RM: We don’t.
MR: -that’s the good news. And so those of us who overeat and then say ‘I’m going to skip breakfast, right?’ Wrong. When you skip breakfast, you go into a famine mode-
MR: -that that gene turns on and it says “Ack!” no more calories consumed or way cut down, so you then don’t burn your normal calories. And it takes a while; it’s like a factory turning on and off. You gene turns on and it takes a while for it to turn off again. So that preserves, if you will, body fat, so you preserve it. So that’s the theory of a-
RM: That’s the theory.
MR: -thrifty gene genotype.
RM: So if there were a real famine, sixty percent of us would do well?
MR: Well it depends on how good we were at storing food and shopping. You know, it’s another subject you’re getting into which is-
RM: Okay, well we won’t go there.
MR: -how well our Americans prepare for emergencies. So when I lived in California we used to have earthquake preparedness where my wife and I would turn off the gas and turn off things and see if we could survive a week. Well we only tried the survival weekend without gas, electricity, without exogenous food, what we had stored. We aren’t very well prepared to survive.
MR: As Californians where the earthquake zone is toughest, it’s only like fifteen percent of them had to survive three days without gas and electricity-
MR: -and extra food.
RM: So it’s not really as big an advantage as it might seem?
MR: Well you know,-
RM: In a famine.
MR: -we don’t know. Hopefully we won’t have to survive a famine to find out the answer to your question.
RM: Right now we have to survive…, right?
MR: Right. That’s right.
RM: Thank you, Doctor Roizen.
MR: Thank you, Raena.
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