Question: when is a pound lost a pound gained? Answer: on a diet

Female weight-watchers can look forward to an unexpected bonus: pounds lost around the bottom equal pounds gained in the pocket, according to the first research into the financial benefits of dieting.

Female weight-watchers can look forward to an unexpected bonus: pounds lost around the bottom equal pounds gained in the pocket, according to the first research into the financial benefits of dieting.

A woman who drops from being overweight to normal is better off to the tune of £7,000, say scientists who looked at the effects on women's overall wealth. An obese female who dropped to normal weight would find herself almost £15,000 richer. While there has been considerable research on the health implications of obesity, an issue of major concern for politicians and medics alike, there has been little focus on the wider effects of weight gain and loss.

"The results suggest that women pay the heaviest financial penalty for being overweight," say the researchers, who report their findings in the journal Economic and Human Behaviour this week. "Individuals who lose large amounts of weight have a dramatically improved financial position."

The researchers found that a one-unit increase in Body Mass Index (BMI) for a man results in an average drop in wealth of around 8 per cent. For women the decline was steeper, at 12 per cent.

Marriage and education also increase a woman's wealth, says the study, while divorce reduces it. The researchers calculated the net worth of married women at 229 per cent - more than double - that of singletons.

The research at Ohio State University suggests that the link between wealth and being overweight may even have had an impact on national saving rates. "If BMI changes are negatively associated with savings, then continued BMI increases could presage further declines in the savings rate," said Dr Jay Zagorsky, who led the study. In the research, the academics used an American database of people born between 1957 and 1964 and who have been monitored ever since.