In their study, Eva Munster and her colleagues at the University of Mainz tracked the weight of more than 9,000 people.

They found that while 11 percent of those who were not in debt were classified as obese, a full quarter of those who were in debt met the medical criteria for obesity.

Writing in the early online edition of BMC Public Health, the researchers say they took into account the income of the participants, and the link between debt and obesity "was not explained by components of traditional socioeconomic status definitions such as education and income."

"The recent credit crunch will have health implications for private households. While income, education and occupational status are frequently used in definitions of socioeconomic status, levels of debt are not usually considered," Munster added in a journal news release. "We've shown that debt can be associated with the probability of being overweight or obese, independent of these factors."

Her team speculates that certain lifestyle changes linked to debt, such as restricted daily activities, "comfort eating" and poorer available food choices may all contribute to packing on pounds during financial hard times. For example, "a person's ability to pick and choose the food they eat often depends on the financial resources they have available," Munster said. "Energy-dense foods such as sweets or fatty snacks are often less expensive compared to food with lower energy density such as fruit or vegetables."

More information

Find out how to fight obesity at the American Heart Association .