Your health is not just what happens to you, but is influenced by all of those around you and the environment. Some environments are toxic to health.

The past seven years have been rough for Michelle Miller. After splitting with her husband, the mother of two struggled to keep a job, had to move in with her parents and gained 100 pounds.

Miller, who brings in about $1,000 a month managing a recording artist, correlates her expanding waistline with her shrinking budget. And, MSN Money reports, research backs her up.

Americans across all income levels are getting fatter, according a 2010 Centers for Disease Control study of socioeconomic status and obesity. The number of obese people in the United States doubled between 1980 and 2000. Among men, obesity rates are similar regardless of money. Among women, though, the rich tend to be thinner. Forty-two percent of women with incomes flirting with the federal poverty line are obese, compared to 29 percent of wealthier women.

Adam Drewnowski, director of the Center for Obesity Research at the University of Washington, claims he can gauge the income level of a lecture audience by taking note of the number of obese women in the room.

"If one third of my audience is obese, I don't think 'These are people with weak willpower or who made bad choices,'" he told MSN Money. "I say, 'These are women who do not make more than $40,000 a year."

Wealthy neighborhoods in Seattle boast obesity rates as low as 6 percent while, in poor areas, obesity is closer to 30 percent, according to Drewnowski's research.

A study published in the New England Journal of Medicine in October further concluded the opportunity to move from a high-poverty neighborhood to a low-poverty neighborhood was associated with "modest but potentially important" reductions in the prevalence of extreme obesity. Switching neighborhoods had a similar effect to best-practice lifestyle interventions and medication use.

For that study, sponsored by the U.S. Department of Housing and Urban Development, 4,500 women were divided into three groups. One group was given a rent-subsidy voucher that could only be used in neighborhoods with a low poverty rate. Another was given an unrestricted rent-subsidy voucher. The third did not receive a rent-subsidy voucher. When researchers followed up with the women 10 and 15 years later, those who were required to move to low-poverty neighborhoods showed a reduction in the risk of extreme obesity and diabetes.

"This is one of the first studies to show that where you live — the circumstances of your neighborhood, the social characteristics of the people around you — all these things may play a role in your own health," Dr. Harlan Krumholz, a cardiologist at the Yale School of Medicine, told the Los Angeles Times. "Your health is not just what happens to you, but is influenced by all of those around you and the environment. Some environments are toxic to health."

Researchers have tossed about several hypotheses to explain the phenomenon, including lack of access to healthy food, medical care and facilities that encourage physical activity like gyms and parks. Psychological stress from money troubles may also contribute to weight gain.

Low-income people tend to eat diets higher in fat and sugar and lower in nutrients, Drewnowski said. This can be explained, in part, by the fact that low-nutrient diets are cheaper. In his research, Drewnowski found customers of lower-cost grocery stores are 10 times more likely to be obese.

18 comments on this story

"The minute you move to an area served by Wal-Mart — because they place themselves in lower-income areas — you will be surrounded by obesity," he said.

Dr. Barry Franklin, advocacy coordinating committee chair for the American Heart Association, argues, though, that behavioral choices still remain the No. 1 risk factor for obesity.

"We also know that lower socioeconomic levels are associated with poor health choices," he told Heart Wire. "It's the choices we make on a day-to-day basis, and I have to believe that the more education you have, the more likely you are to make some, but not all, of the right choices."