Everyone knows these days that American kids are getting fatter. The Surgeon General of the United States now ranks childhood obesity as a top public health concern. But it's not just their waistlines we need to worry about; our kids are getting sicker, too.

Pediatricians like me see more and more children with what I call the "high" diseases: high blood sugar, high cholesterol, and high blood pressure. Once upon a time, these conditions  -- all related, in large part, to body weight and what we eat  -- were called "adult-onset diseases." Not so anymore. Sometimes we see children as young as five years of age with these "highs." But while there's an epidemic of food-related illnesses, the good news is that they're preventable. How? Through good nutrition, and by shaping young tastes as early as possible.

I consider "taste shaping" to be one of the best and most important ways  -- right up there along with immunizations and regular pediatrician visits  -- that parents can help keep their kids healthy. Taste shaping means feeding your baby (as soon as she starts eating solids) fresh, nutritious foods that program her developing palate to prefer healthy fare. One of the most common complaints I hear from moms is "My toddler will only eat sweetened foods," or "My child hates green vegetables." That's because these kids' tastes have been programmed in the wrong nutritional direction. But they can be programmed to love unsweetened foods and healthier choices (including that dreaded broccoli and spinach), too.

I developed this "taste-shaping" concept by studying patients in my pediatric practice. Early on in my career, I noticed there were a group of moms who never let their kids eat junk food. At first, I thought they were just health-food nuts, but as I followed their children through the years, I realized they didn't get sick as often. Not only did they have healthier bodies, but they had healthier brains, too. When they entered school, they were less likely to be tagged with learning problems.

My observations led me to investigate an emerging science called metabolic programming, which studies how infants' pre- and postnatal nutrition can affect their health later in life, just as key events in early childhood can shape a person's personality as an adult. Depending on what you feed your baby, you can direct her growing metabolism toward developing either a resistance or a susceptibility to certain illnesses. Basically, it's a fancy way of saying, "You are what you eat."

Metabolic programming research is still new, but it makes great sense to me and I now discuss it with all the parents in my practice. Of course, shaping your baby's tastes to prefer healthy fare won't happen in a day, and the moms I see in my practice always have a lot of questions ("You expect me to never give my kid a french fry?" being high on the list) about how to do it. Here's how I answer them  -- and how you can help your child grow up loving the foods you probably thought he'd hate:

William Sears, M.D., is a Babytalk contributing editor and the author of more than 30 books on childcare.