How was the relationship between genes and nutrition discovered?

A now famous study conducted at Stanford University looked at the long-term effects of weight loss using a few different diets assigned at random. Results showed that some participants lost weight on one type of diet, such as low-fat, while others did not. The study then tested participants' DNA for 3 specific gene variations and found that those using the best diet for their DNA lost as much as 2 1/2 times more weight than those not using their best DNA diet. 

"This genetic testing is a brand new field, nutrigenomics, the link between genes and nutrition," says David Katz, MD, nutrition expert and founder of the Yale Prevention Center. "It makes sense because our genes control hormone levels, enzyme levels -- all the basic levels of metabolism. And how we metabolize food determines what happens to the nutrients and calories we take in."