She blamed the trend on the high price of healthy food, and a tendency for people worried by debt to comfort eat.
She worked with a team of researchers to study more than 9000 people, finding that 25 per cent of the 949 people in debt were medically obese, compared to only 11 per cent of the remaining 8318 participants.
She said: "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. We've shown that debt can be associated with the probability of being overweight or obese, independent of these factors."
The researchers say that debt can affect a series of risk factors for chronic diseases, for example by limiting leisure time activities and participation in social events.
The quality of an individual's diet can also be negatively affected.
Münster said: "A person's ability to pick and choose the food they eat often depends on the financial resources they have available. 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."