Overweight people who trim down substantially may improve both their health and their wealth, if new research is correct.

The study, based on 15 years’ worth of data from a large U.S. survey, found that both weight and weight changes were related to people’s net worth - their assets minus their debts.

In general, people with a normal body mass index (BMI) had the highest net worth, and heavy people who lost a significant amount of weight tended to see their wealth increase. Minor weight changes, on the other hand, showed little financial effect.

The pattern was not neat, however.

In particular, obese black men had a greater net worth than slimmer black men, and overall, there was no clear association between BMI and wealth among African-American males.

In contrast, being thin helped white women’s bottom lines the most, according to findings published online by the journal Economics and Human Biology. A white woman’s net worth peaked when her BMI was just above the threshold for “normal,” while that of white men and black women was greatest when their BMI was at the higher end of normal.

White women also lost the most in terms of absolute dollars as BMI increased.

Similarly, women and white men tended to gain wealth after losing a large amount of weight. For example, a typical white male who trimmed 10 points from his BMI - equivalent to a 6-foot-tall male going from 250 to 175 pounds - had a wealth increase of $12,720. But again, black men differed in that their net worth dipped slightly with such a drastic weight change.

The reasons for the racial and gender discrepancy are not clear - nor is there an easy explanation for the relationship between weight and wealth, according to study author Jay Zagorsky, a researcher at Ohio State University’s Center for Human Resource Research in Columbus.

A person’s body size does not seem to affect measures of wealth like capital gains made from stocks, he told Reuters Health, and so it would appear that weight affects income specifically.

Other researchers, according to Zagorsky, have speculated that heavy people may face discrimination in the workplace, which could lower their incomes. Obesity might also raise a person’s spending, on food or treatments for obesity-related health conditions, for example.

The study drew on data from the National Longitudinal Survey of Youth, a large nationally representative survey of Americans born between 1957 and 1964. Zagorsky based his findings on data collected between 1985, when respondents were at least 20 years old, and 2000.

The results indicate only an association between weight and wealth, and not a definite cause-and-effect relationship. However, Zagorsky pointed to some evidence that it’s weight that affects wealth, rather than the other way around.

A subanalysis of survey respondents whose wealth was suddenly boosted with an inheritance found that these individuals had no significant changes in BMI in the following years.

SOURCE: Economics and Human Biology, online July 2005.