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January 18, 2011

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Adolescent obesity may finally be turning around, but not for all groups

Aug. 15, 2010
Courtesy of the Uni­vers­ity of Cal­i­for­nia-San Fran­cis­co
and World Science staff

A­mid what many ex­perts call an obes­ity ep­i­dem­ic, obes­ity rates may be fi­nally start­ing to de­cline and level off among many U.S. ado­les­cents, a study has found.

Un­for­tu­nate­ly, its au­thors say, some mi­nor­i­ties aren’t ben­e­fit­ing from the trend and con­tin­ue to suf­fer ris­ing obes­ity rates. That un­der­scores a need for more tai­lored in­ter­ven­tion pro­grams and poli­cies that tar­get high-risk groups, said the Uni­vers­ity of Cal­i­for­nia-San Fran­cis­co sci­en­tists who did the re­search.

The stu­dy, billed as the first to find sig­nif­i­cant dif­fer­ences in obes­ity trends over time by race and eth­nicity, ap­pears on­line in the jour­nal Pe­di­at­rics and is slat­ed to ap­pear in its Sep­tem­ber print is­sue.

“While the de­cline and sta­bil­iz­a­tion of obes­ity among cer­tain groups is en­cour­ag­ing, we are see­ing an in­crease in dis­par­i­ties that is trou­bling, es­pe­cially among the most se­verely obese youth,” said Kris­tine Mad­sen, pe­di­a­tri­cian at the uni­vers­ity and one of the re­search­ers. They ex­am­ined trends in the prev­a­lence of high body mass in­dex, a stand­ard meas­ure of obes­ity, among His­pan­ic, non-His­pan­ic white, Asian, black, and Amer­i­can In­di­an ado­les­cents in Cal­i­for­nia from 2001 through 2008. 

They found that obes­ity rates de­clined or sta­bilized dur­ing the time stud­ied for some groups. Among white and Asian girls and boys, obes­ity rates peak­ed in 2005, then de­clined over the next three years, with 2008 rates com­ing in at 12 per­cent for white youth and 13 per­cent for Asians. 

Over­all rates for His­pan­ic youth al­so were found to peak in 2005 and then lev­el off at 26 per­cent through 2008; al­though His­pan­ic boys did show a small de­cline on their own. Rates among black boys stayed at the same lev­el each year.

How­ev­er, the re­search­ers said obes­ity rates con­tin­ued to climb for black and Amer­i­can In­di­an girls, reach­ing 22 per­cent and 23 per­cent, re­spec­tive­ly. Fur­ther­more, these two groups were more than three times as likely as white girls to be se­verely obese.

The in­ves­ti­ga­tors found that only Asian youth and white boys showed any signs of de­cline in se­vere obes­ity af­ter 2005. All oth­er groups – in­clud­ing His­pan­ic boys and girls, white girls, black boys and girls, and Amer­i­can In­di­an boys and girls – peak­ed in 2005 and then re­mained at a plat­eau through 2008.

“When you look at the very heav­i­est end of the spec­trum, the pic­ture is pret­ty bleak, and we do not yet know if se­vere obes­ity rates for these groups will re­main at a plat­eau or con­tin­ue to in­crease,” Mad­sen added.

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Amid what many experts call an obesity epidemic, obesity rates are finally starting to decline among U.S. adolescents, a study has found. Unfortunately, its authors said, some minorities aren’t benefiting from the trend and continue to suffer rising obesity rates. That underscores a need for more tailored intervention programs and policies that target high-risk groups, said the University of California-San Francisco scientists who did the research. The study, billed as the first to find significant differences in obesity trends over time by race and ethnicity, appears online in the journal Pediatrics and is slated to appear in its September print issue. “While the decline and stabilization of obesity among certain groups is encouraging, we are seeing an increase in disparities that is troubling, especially among the most severely obese youth,” said Kristine Madsen, pediatrician at the university and one of the researchers. They examined trends in the prevalence of high body mass index, a standard measure of obesity, among Hispanic, non-Hispanic white, Asian, black, and American Indian adolescents in California from 2001 through 2008. They found that obesity rates declined or stabilized during the time studied for some groups. Among white and Asian girls and boys, obesity rates peaked in 2005, then declined over the next three years, with 2008 rates coming in at 12 percent for white youth and 13 percent for Asians. Overall rates for Hispanic youth also were found to peak in 2005 and then level off at 26 percent through 2008; although Hispanic boys did show a small decline on their own. Rates among black boys stayed at the same level each year. However, the researchers said that from 2001 through 2008, obesity rates continued to climb for black and American Indian girls, reaching 22 percent and 23 percent, respectively. Furthermore, these two groups were more than three times as likely as white girls to be severely obese. The investigators found that only Asian youth and white boys showed any signs of decline in severe obesity after 2005. All other groups – including Hispanic boys and girls, white girls, black boys and girls, and American Indian boys and girls – peaked in 2005 and then remained at a plateau through 2008. “When you look at the very heaviest end of the spectrum, the picture is pretty bleak, and we do not yet know if severe obesity rates for these groups will remain at a plateau or continue to increase,” Madsen added.