Genes Versus Environment: Why are Kids Eating More and Moving Less?

Complexities of behavior: It is impossible to boil down the mysteries of human behavior into simple either-or, genes-or-environment questions. Yet in the context of childhood obesity, we must determine which factors in kids' genes and environments cause them to eat more, move less, and pack on the pounds. By identifying the primary contributors of the obesity epidemic, we will be able to more effectively guide policy intervention efforts.

Experiments have identified potential “obesity genes” – e.g., leptin and other cell-cell signalling hormones – that normally function to regulate appetite, hunger, satiety (fullness), and food intake. (17) The take-home lesson: “obese genes” do not directly cause obesity, but instead interact with the environment to increase a person's risk of energy imbalance and fat buildup. (17,23)

Evolution (natural selection and gradual shifting of a population's gene pool) occurs over billions of years, and the human gene pool has not changed drastically over the past 30 years of the fat epiemic. (19,24) It is thus not a new obesity gene, but a change in society and culture, that has spurred the increasing prevalence of childhood overweight. (20,24)

Toxic environment: Over the 2nd half of the 20th century, we experienced major changes in lifestyle, family dynamics, media prevalence and content, community structure, educational philosophy, and governmental priorities. (3,21,25) Today, we live in a world that isolates children and drives them toward outlets in food and sedentary activity.

In a powerful Call to Action , the Surgeon General called for collective action: “Many people believe that dealing with overweight and obesity is a personal responsibility. To some degree they are right, but it is also a community responsibility.” (2)