White women saw the greatest increase in wealth as they dropped pounds. Black women and white men also gained financially as they lost weight, but to a lesser extent. The wealth of Black men basically was unaffected by their weight.

There's no way to tell from the data whether losing weight was the reason for the gain in wealth, but the linkage definitely was there, said Jay Zagorsky, author of the study and a research scientist at Ohio State University's Center for Human Resource Research.

"The typical person who loses or gains a few pounds had almost no change in wealth, but those who lost or gained large amounts of weight had a more dramatic change," Zagorsky said.

Different Ideal BMIs

The study, which appears in the "Articles in Press" section of the journal Economics and Human Biology, is based on data from about 7,300 people who participated in the National Longitudinal Survey of Youth (NLSY).

Funded primarily by the US Bureau of Labor Statistics, the NLSY is a nationally representative survey conducted by Ohio State's Center for Human Resource Research.

Because the same people are interviewed repeatedly in the survey, Zagorsky was able to see how the obesity levels and wealth of respondents changed over time. He used data from 12 NLSY surveys conducted between 1985 and 2000 All the respondents were between 21 and 28 years old in 1985.

He calculated BMI scores using each respondent's height and weight figures. Scores under 18.5 are considered underweight, 18.5 to 24.9 are normal, 25 to 29.9 are overweight, and 30 or higher are considered obese.

The respondents also gave information about their net worth, which included home values, cash savings, stocks, bonds and auto values, among other assets. Outstanding debts were subtracted from that total to arrive at net worth.

Overall, the results showed that a one unit increase in a young person’s BMI was associated with a $1,300 or 8 percent reduction in wealth. But the changes varied dramatically by ethnicity and gender.

Increases in BMI had no link with the wealth of Black men, and were associated with small negative changes in the wealth of white men. Increases in BMI were linked to medium negative changes in wealth for Black women and large negative changes for white women.

The results suggest each category of race and gender has a different ideal BMI to maximize wealth, Zagorsky said.

Workforce Discrimination?

White women had peak net worth at the low end of the normal range (BMI 20), white males and Black women reached peak net worth at the upper end of the normal range (BMI 24) and Black males peaked in the obese range (BMI 32).

Participants in this study had to lose quite a bit of weight to show strong improvements in wealth, Zagorsky emphasized.

For example, when a typical young person decreased his or her BMI by one point, wealth increased by only $234. But when a person lost enough weight to go from the middle of the overweight category (BMI 27.5) to the middle of the normal category (BMI 21.7), wealth increased by an average of $4,085.

"If you really want to impact your wealth, you have to move from overweight or obese into the normal range," he said. "You can't just drop 5 or 10 pounds and change your wealth."

The data in this study can't tell us whether a person’s wealth affects obesity, or whether obesity affects wealth.

However, it is more likely that weight influences wealth, Zagorsky said. An analysis of people in the study who received inheritances -- suddenly increasing their wealth -- showed no dramatic changes in their BMI scores in the following years. This suggests that wealth does not have a strong influence on weight.

However, if weight does affect wealth, there is also the question of how it does so.

One possible explanation would be that overweight and obese people are discriminated against in the workforce and don't earn as much money as normal weight people.