The USPSTF (US Preventive Services Task Force) recommends that clinicians screen children aged 6 years and older for obesity and offer them or refer them to intensive counseling and behavioral interventions to promote improvements in weight status.

However, other work from Harvard researchers suggests that we need to start even earlier:

Prenatal to age five critical period

March 1, 2010

Kelli Whitlock Burton
Harvard Medical School

Efforts to prevent childhood obesity should begin far earlier than currently thought — perhaps even before birth — especially for minority children, according to a new study that tracked 1,826 women from pregnancy through their children’s first five years of life.

Most obesity prevention programs — including the national initiative recently launched by first lady Michelle Obama — target kids ages 8 and older. Scientists at the Harvard Pilgrim Health Care Institute’s Department of Population Medicine, an affiliate of Harvard Medical School(HMS), now say that factors that place children at higher risk for obesity begin at infancy, and in some cases, during pregnancy. Their research also suggests that risk factors such as poor feeding practices, insufficient sleep, and televisions in bedrooms are more prevalent among minority children than white children….