(HealthDay)—A comprehensive survey on the widening American waistline finds that as paychecks get bigger, women's average weight tends to drop.
But men aren't following suit.
Based on 2014 data, "obesity prevalence was lower in the highest income group among women, but this was not the case among men," according to a team from the U.S. Centers for Disease Control and Prevention.
In the study, researchers led by CDC statistician Cynthia Ogden looked at U.S. federal health data from 2011 through 2014.
The investigators found that, overall, about 31 percent of people in the highest income bracket—$83,000 and above for a family of four in 2014—were obese.
That's compared to about a 40 percent obesity rate for people with family incomes below that level, the researchers noted.
But gender seemed to matter.
Women's obesity levels fell precipitously as income rose—from about 45 percent for women at the poverty line, to about 43 percent for women in the middle-income group, and then to under 30 percent for women at the higher level of income, the findings showed.
The CDC team noted that the trend seemed specific to white women. For black women, obesity rates remained roughly the same, regardless of income.
And there was no similar trend for men. In fact, the highest obesity rate for American men was in the middle-income group, at 38.5 percent. That's compared to men who were either at the poverty line (a 31.5 percent obesity rate) or in the higher income bracket (32.6 percent).
There was one more anomaly in the statistics: black men. The research showed that their rates of obesity actually rose as their incomes got higher.
"Obesity prevalence was higher [for black men] in the highest income group [42.7 percent] than in the lowest income group [33.8 percent]," Ogden's team reported.
The study wasn't equipped to tease out the reasons behind all of these trends. However, higher education did seem to help keep American waistlines trim.
The findings showed that while about 40 percent of people who had a high school diploma or less were obese, that number dropped to just under 28 percent for college graduates.
The study was published Dec. 22 in the CDC's Morbidity and Mortality Weekly Report.
Explore further: Don't blame food stamps for obesity in America
There's help on keeping weight gain at bay at the American Heart Association.