Since 1900, every generation of Americans has been healthier than the one before. The result has been a steady and sometimes dramatic improvement in life expectancy and declining rates of disability among the elderly.

But doctors and researchers have begun to worry that obesity among the young may reverse the trend toward shorter periods of infirmity and could even erase gains in life expectancy. A recent study by Stanford assistant professor of medicine Jay Bhattacharya, ’90, MD ’98, PhD ’01, and RAND researchers Darius Lakdawalla and Dana Goldman, PhD ’94, revealed substantial growth in disability rates among persons under 50. The number of disabled persons ages 30 to 39 grew from 118 per 10,000 to 182 per 10,000 between 1984 and 1996, the report found. The proportion of diabetes-related cases across all age groups in the study doubled—a strong sign that obesity is a contributing factor, say the authors.

At a policy summit of doctors, researchers and nutritionists in early June, Health and Human Services Secretary Tommy Thompson pulled no punches. “Let’s be clear, friends, we do have a crisis on our hands. Obesity is on the verge of overtaking tobacco as the leading preventable cause of death in America.” He added that poor eating habits and lack of exercise “are literally killing us.”

Assuming that the coming elderly population boom brings with it additional health care burdens, the prospect of increasing illness among the young is alarming, says psychology professor Laura Carstensen. “We could be looking at a generation of people who will be sicker earlier than the previous generation. And that is a truly disastrous scenario.”

Policy makers in government, education and medicine should immediately begin a concentrated effort to reverse unhealthy lifestyle trends, she says. “That means you probably don’t want to serve pizza and Cokes in schools, but we’re doing that now.” Some states, including California, have banned soft-drink sales in elementary schools.

Experts also say physical education must be put back in school curricula, not only because it keeps kids fit but also because it promotes an active lifestyle. The percentage of children who are overweight has more than doubled since 1980, according to the Centers for Disease Control and Prevention. Nationally, 50 percent of school children age 12 and over regularly participate in athletic activity, compared to 80 percent who did so 30 years ago. “That’s a travesty,” Thompson said.