Getting heavier, younger: generational shift in obesity found

But a new study by the University of Michigan Health System on obesity trends shows Americans are getting heavier younger and carrying the extra weight for longer periods over their lifetime.

As a result, the study suggests the impact on chronic diseases and life expectancy may be worse than previously thought. The findings will be published April 12 in the International Journal of Obesity.

Researchers used a wide range of national data on children and adults born between 1926 and 2005 to reveal the troubling trend of younger generations becoming obese earlier in life than their parents and grandparents.

According to the study, 20 percent of those born 1966-1985 were obese by ages 20-29. Among their parents, those born 1946-1955, that level of obesity was not reached until ages 30-39, not until ages 40-49 for individuals born between 1936-1945, and obesity prevalence was even later -- during the 50's -- for those born between 1926-1935.

Further research is needed to understand the future effect the obesity trend will have on diabetes rates and mortality.

"Many people have heard that Americans are getting heavier," says lead author Joyce Lee, M.D., M.P.H., a pediatric endocrinologist at the U-M C.S. Mott Children's Hospital and assistant professor in the Department of Pediatrics and Communicable Diseases at the U-M Medical School. "But it's very important to understand who the obesity epidemic is affecting.

"Our research indicates that higher numbers of young and middle-age American adults are becoming obese at younger and younger ages," she says.

Evidence shows body mass index, a calculation of fat and weight, increases with age, and children who are obese are more likely to become obese adults.

Obesity is a well-known contributor to type 2 diabetes, cardiovascular disease, disability and premature death.

The prediction, made in 2005, for a reduced life expectancy in the 21st century, was based on obesity prevalence from the period 1988-1994, the mid-point of the obesity epidemic, and included much older adults, born 1885-1976, a generation that had much lower obesity rates over their lifetime.

The federally funded U-M study shows obesity trends were worse for women and blacks, a bad sign for reversing racial disparities in health, U-M authors say. Among 20-29-year-olds, born 1976-1985, 20 percent of whites were obese compared to 35 percent of blacks in that age group.

"What is particularly worrisome is that obesity trends are worse for blacks compared to whites," Lee says. "Black Americans already experience a higher burden of obesity-related diseases and the obesity trends will likely magnify those racial disparities in health."