Comment from Nicole: I've been reading a lot about sugar recently ... how it's a toxin and should be a regulated substance. It's scary to think that we are putting something that's so bad for you in our bodies on a regular basis. Should we try to cut it out completely or what limits should we put on it?

John Whyte: It's hard to cut out sugar completely. Sugar can be a source of energy, and natural sugar — from fruit — is useful to our bodies. But I do recommend you limit sugar consumption. Definitely eliminate all the sugary beverages — soda, sweetened teas, specialty coffees — and check food labels. Fat-free foods are often loaded with sugar.

Comment from Diane: Is there any exercise I can do with my mom/dad that will also help me?

John Whyte: Walking is one of the best exercises we can do, and it's a great family exercise. The simple act of walking may also improve memory as we get older. It seems that people who walk more throughout life have greater brain volume than those who walk less. If you walk around seven miles a week, you are half as likely to develop problems with dementia than if you don't walk at all. There are approximately 2,000 steps in one mile. You can check how many steps you take by getting a pedometer — it counts the number of steps you take. If you average 2,000 steps a day, and 14,000 steps a week, I'll be happy!

Comment from Alison: Now that I'm in my 40s, my metabolism is really slowing down. I eat pretty healthy and exercise, but I'm still gaining weight. What can I do? Eat less and exercise more?

John Whyte: It's common to gain weight as we get older. Our basal metabolic rate — basically our internal furnace — slows down as we age. So we need to balance that slowing down of our basal metabolic rate. You can do that through either eating fewer calories or being more active. They're both important — but honestly, weight loss is probably 80 percent food, 20 percent exercise. So I recommend you focus first on eating healthier and fewer calories, and then tackle being more active.

Comment from Jake: What are the three to five best foods you can eat? What about the worst?

John Whyte: We all need to eat more fish — study after study has shown that those who eat fish three days a week have a lower incidence of heart disease and other medical conditions.

People often ask me if there's a magic pill for weight loss. Well, there is — you know what it's called? A blueberry! OK … it's not a magic pill but it is a superfood. It's packed with powerful antioxidants to keep the blood vessels in our heart and brain healthy. So start eating blueberries.

And you need to go nuts over nuts. Sometimes people are concerned about the number of calories in nuts — as long as you keep it to a handful, you'll do OK.

And of course, drink more water.

Your question is great because in order to lose weight and live longer, what we exclude is as important as what we include. So the worst foods are processed meats — the lunch meats — bologna, salami, hot dogs. Soda is your enemy. Anything with high fructose corn syrup should be avoided. If you're currently drinking soda, you need to stop. And all the highly processed foods should be eliminated — all the white breads. Bread is actually the number one source of sodium in our diet. Stop all the doughnuts, bagels and scones. (Scone is really just a fancy word for doughnut!)

Next page: You can make budget-friendly healthy choices. »