Researchers at the University of Washington broke new ground by grouping data gathered from 8,803 respondents by postcode.
Seventy-four postcodes in King County, in Washington state, were included in the study, which found that for every 100,000-dollar increase in the average house price, "zip code area obesity" fell by two percent.
Obesity rates reached 30 percent in the most deprived areas but were only around five percent in the most affluent postcodes, the study, which used property values as a proxy measure of a neighbourhood's socio-economic status, showed.
Earlier studies, using data gathered across a broader geographical spread, showed narrower disparities.
Data gathered across King County showed that the obesity rate among blacks was 10 percentage points higher than for whites, and that people with low annual incomes had a 20 percent obesity rate, compared with a 15 percent rate for those who earned more than 50,000 dollars.
"Obesity is an economic issue," Adam Drewnowski, director of the university's center for obesity research and leader of the study, said in a statement.
"Our research shows that geography, social class and economic standing all play huge roles in the obesity problem," Drewnowski said.
"Some of the most disadvantaged areas -- those hardest hit by low income, low education and low property values -- are also the ones most affected by the obesity epidemic."
A report published earlier this week showed that obesity continued to creep upward in the United States last year, with two-thirds of adults and some 25 million children obese or overweight.
Poorer southern states were particularly affected by the epidemic, said the report by the Trust for America's Health.