Over the last few weeks, thousands of emails have come in asking Dr. Oz this question: "How can I live longer?" Now I remember when you did this for me when I was 50, and my real age was 38, and I was so excited about that. I'd be scared to take it today. But what does it mean, "real age"?Gayle King, Host of Oprah's All Stars

So, a lot of folks when they want to figure out how old they are, they'll do the math. They'll figure out what day was I born, what's the day, subtract it from, and that's what they think their age is. That's wrong.

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You want to know how old your body thinks you are. That's your real age. You know, when you go to your high school reunion, not everyone looks the same even though most of you are the same chronological age, but the physiologic age—how old your body thinks you are—is different.

So, real age is an effort for us to measure that number. And the reason it's so important is because it makes you an adult. It tells you what's causing you to gain age, lose years of life and, for that reason, what you might want to focus on to improve on that. And the biggest news I'm going to talk about today is the fact that if you change your lifestyle over the course of three months, quarter of a year, you can reverse most of the mistakes that you have made, and they're affecting your aging.

That's a dramatic insight that we only recently learned about. But give me three months, and we'll put you back where you could have been your whole life.

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As a reminder, always consult your doctor for medical advice and treatment before starting any program.