Throughout centuries, mankind has been on a quest for the fountain of youth. Yet in a society of super-size meals and easy avenues of convenience, Americans are putting their health -- and eventually their lives -- at risk.

In his latest book, 'Chasing Life,' neurosurgeon and CNN chief medical correspondent Sanjay Gupta, M.D. uncovers key factors for living a longer, healthier life. Below, Dr. Gupta shares simple steps that open the door to preserving our health and in turn, extending our lives, with AOL Body.

AOL Body: What are some simple and inexpensive ways that people can ensure longer life through diet and fitness?

Sanjay Gupta: You have to make it a priority. As much as you think about that meeting planned with the boss at 10AM, you have to think about your body every single day -- it's that important. Having said that, there are some fairly simple things that you can do.

First, don't worry as much about supplements and calorie counting. Worry more about eating seven different colored foods a day. You're much more likely to get vegetables, salads, fruits, things like that that are obviously good for you, but you might otherwise have ignored.

AOL Body: Can you define "colored" foods? Gummy bears are colored foods . . .

Gupta: I'm talking about actual food -- not candy. So, that includes fruits, vegetables, blueberries, eggs could count, chocolate, even red wine. Actual foods that come out of the ground or that are grown on trees.

And, I'm not against meats. Certain meats are OK. I recommend staying away from the fatty meats especially if you are concerned about a history of heart disease, for example. Most every food counts, just not processed sugar.

The other thing is when you eat, as busy as we are, try and eat your water-dense foods [fruit and vegetables such as watermelon, cucumbers, etc.] first. Try to eat foods that are packed with water or drink water before eating more calorie-rich foods. You'll tend to eat less that way.

Also, slow down your eating by even a few minutes. You'll be amazed at how much less you eat. It takes 15 minutes for your stomach to send a signal to your brain that you're full. But in 15 minutes you might have finished a three-course meal. By the way, I've tried all these tips and wouldn't recommend what I think I can't incorporate into my own life.

AOL Body: You stress nutrition throughout the book. What about in terms of fitness?

Gupta: People talk about the importance of getting exercise every day, and for different people that means different things. For some, it might mean getting moving at all. That is, not just going straight from garage, to office, to garage, to bed -- as exercise. Walking during the day as a start would be a great thing.

There are a fair number of people who make a concerted effort to get some form of aerobic activity into their lives. In this country, we've become very aerobic exercise-focused: treadmills, ellipticals, running, all of which are all great exercises. I would add to that some upper body resistance training. It's amazing how much exponential benefit you can get just from doing some upper body training. It tends to ward off osteoporosis, which is a particular problem in women, and in men, as well. It also improves your posture and it seems to improve your chances of beating pneumonia as you get older, which can be a big killer.

AOL Body: You also mention green tea, garlic and wine while discouraging people from looking to supplements instead of getting regular vitamins and minerals.

Gupta: My point was not to indict supplements or condone green tea. My research is based on interviews with people who I trust in the field, like Andrew Weil, M.D. for example, who is arguably the father of supplementation and integrative medicine.

It's to say that the whole scientific process by which you take the good stuff out of foods or other substances and translate them into a pill form just doesn't seem to work. It's not that it's a bad idea; it's not that people aren't trying to do right by their bodies. But if you think you're getting broccoli from a pill, you're probably not. What you're likely getting is a few micronutrients that appear in broccoli. If you want to get the benefits of green leafy vegetables or the antioxidant properties of green tea, you need the substance itself. The absorption and the whole capability of you being able to benefit from that in some way is based on the whole thing as a matrix: the food together, and the supplements with the micronutrients.

AOL Body: You mention the Japanese phrase, "hara hachi bu," quite a bit in your book. What does it mean?

Gupta: It means to push your plate away before you're full, when you're 80 percent full. The only life extension diet we know of is a caloric restriction (CR) diet. There are huge numbers of people around the country who already do a CR diet. More than that, people who push that plate away before they're full allow their brains to catch up with their stomachs. As a result, they eat less without feeling hungry.

AOL Body: How can people get motivated? In the last half of your book, you mention attitude and stress levels as factors to living longer.

Gupta: In the book I try not to sound preachy; I'm not a motivational coach. I spoke to various people and they all had interesting stories. Everyone had a different thing that motivated them. I think ultimately it's some sort of life event that makes people want to make their health a priority.

Similar to when people have kids and they research everything about schools in their neighborhoods and the best places to live, sometimes it's seeing a loved one sick or a brush with your own mortality. When you actually see that your body is not immortal -- that it has failings -- you want to work to try to prevent some of those things. That tends to motivate people.Really educating yourself about what can go wrong with your body -- what it's like to have a stroke, to develop lung or heart disease -- makes you want to take care of it, the same way that you take care of anything else in your life.

AOL Body: Throughout your book, you encourage readers that it's never too late to take care of your health. You mention James Hammond, a former CEO turned Olympic runner in your book. Hammond decided to take up Olympic running at the age of 86. What are some key factors and steps people can take at different stages in their lives to become more fit and healthy?

Gupta: It does depend on what your state of health is. Age is not really measured in years. Hammond, I would venture to say, is probably younger now than he was in his late 60s, early 70s. Now, he's almost 90. You have to measure age by your health, and you can make yourself younger.

If you're someone in your 40s, and you're exercising already, push yourself a little harder. Whatever you're doing, amp it up a notch. If you're running, run a little further, or faster. Add more weight training. Be more regimented about your diet. Just amp it up a notch.

In your 50s, if you're someone who has started to pull back on your exercise, try to take yourself back to the point you were at in your 30s or 40s. There's no reason you can't -- your body should be able to tolerate that.

If you're in your 60s and 70s, it's important to just simply stay active in some way or another, and add that upper body resistance training. Especially at that age, the upper body resistance training could help you live longer, could help you chase life and cheat death. It depends on where you are biologically rather than your age, but those are some rough guidelines.

AOL Body: In your book, you write about cancer and different preventive care. What are the big dangers that threaten or shorten life for Americans?

Gupta: There are three big killers. Heart disease is by far the biggest killer of Americans, although cancer could threaten to take that over sometime soon. We've gotten better at taking care of heart disease, but it still is the biggest killer of women -- and men -- in this country.

Added to that is the burgeoning obesity epidemic among children as well, which means that the heart disease rates and stroke rates for younger people could explode in the next 20 to 30 years. People in their late 20s have heart attacks -- it's absolutely amazing, and I think that's one of the biggest threats. Luckily, it's one of the most fixable as well.

Cancer comes after that, then lung disease. In young people, it's trauma, and not wearing your seatbelt -- risky behavior. So it depends at what stage in life you are, but those are some of the biggest risks.

AOL Body: With recent studies noting the exponential rise of diabetes and Alzheimer's disease, what are your thoughts on these conditions?

Gupta: It's amazing to me. [Diabetes] used to be this unusual disease that you didn't see very much. Now, there are different types of diabetes. There's one type that's typically genetic and a second type that appears to be acquired, and often times in relation to one's body size and ability to absorb insulin.

Typically, when a kid had diabetes, it was genetic, plain and simple. But now you're seeing Type II diabetes in children. I never thought we'd be talking about Type II diabetes and children in the same sentence, but we do. It's a direct reflection of the childhood obesity problem. I mention childhood obesity and you can see people's eyes glaze over upon mention. But everything we're talking about in terms of chasing life and improving life's function and otherwise could be erased by the childhood obesity problem.

Unfortunatley, I think diabetes numbers are going to go up, maybe exponentially, if we can't control the childhood obesity problem.

In terms of Alzheimer's, we are a changing demographic. We have many more older people than we have young people in our society. As much attention as we used to focus on heart disease, when these baby boomers were in their 40s and 50s, a lot of that attention is now going to be on dementia and Alzheimer's. I think in some ways we're going to make some real advances. Personally, I think the great advance ultimately is going to be a vaccine. We may see an Alzheimer's vaccine in the next 20 to 30 years.

AOL Body: You touch on new research about scientists looking to bottle the fountain of youth. What new research is out there, including stem cell research?

Gupta: There's a lot going on with regard to stem cells. Most of it is unregulated and untested. As the old adage goes, "where there's smoke, there's fire." People believe these stem cells, as they do in Russia where I visited [presented in the opening of 'Chasing Life'], could help rejuvenate cells that have grown old and damaged. Exactly what the mechanism is, is unclear, but it does seem to have some benefit. The scientist I spoke to in Russia -- and I could not independently validate this -- believes that it tightens your skin, darkens your hair, improves your muscle mass, reduces your body fat and biologically makes you younger. I think there's something there -- while I don't think it's the fountain of youth, it could help turn back some of the markers of time.

AOL Body: Researching your book, what were some of the most outrageous treatments and means that different scientists or people went through for a longer life?

Gupta: The irony with stem cells is that it could be considered outrageous. It's completely untested. Putting these cells in your body that could potentially grow into tumor cells and could grow with wild abandon throughout your entire bloodstream and your organs -- that's definitely a concern. So, I think that people who would do this on human beings without adequate trials first, is pretty scary.

You mentioned Hammond, an 86-year-old former CEO who decided to become a sprinter. There are a lot of older people who are inspired by him and frightened by him at the same time. This speaks to the fact that people are thinking that at some point they've reached the end of their life and that they just can't do this [take care of their health and body] anymore. And it's just not the case.


More about the book, 'Chasing Life'


Eleanor Hong is an editor for AOL Body. Intern Carly Popofsky contributed to this report.