Nutrigenomics – a science that examines how your genes interact with the food you eat – is finding that one size (so to speak) definitely doesn’t fit all. For example, do you eat healthy but still carry some extra pounds, while your friend eats all she wants and stays a size 6? What’s in your DNA could explain why. Although still in its infancy, nutrigenomics suggests that a personalized diet, coupled with advice on disease prevention, may hold the key not only to weight loss but to avoiding some chronic diseases, such as diabetes, heart disease – and maybe arthritis, too.

Examining diet and genes is an active area of research. Some studies have shown that people with specific genes are especially susceptible to effects of fat in their diet, for instance. Other research has shown that people with a different gene can reduce their risk for colon cancer by adding more vitamin D to their diet, whereas others without the gene wouldn’t see the same benefit.

The holy grail is a personalized diet, says Michael Falk, PhD, executive director of the nonprofit Life Sciences Research Office in Bethesda, Md. Current dietary recommendations are geared toward the average person.

Scientists haven’t gotten that far yet, because the interactions between genes are so complex, and because your environment as well as your genes influences your food choices. But that’s not stopping some biotech companies from selling genetic tests to consumers. Swab your cheek, mail it to the lab and get a detailed report on your genetic predisposition to several diseases as well as a nutritional plan to help combat them for anywhere from $100 to $1,000.