The "invisible hand of the market" may be contributing to the obesity epidemic by facilitating the spread of fast food, a new study finds.

The study, conducted by researcher based in the U.S. and Ireland, was published in the February edition of the Bulletin of the World Health Organization.

Looking at data from 1999 to 2008 spanning 25 high-income countries, the team of researchers studied the number of fast food transactions per capita and compared them with figures on body mass index (BMI).

They found that an increase in the average number of annual fast food transactions per capita was associated with an increase in BMI.

While all 25 countries experienced an increase in the average number of annual fast food transactions per capita, the lowest increases were in countries with more stringent market regulation, such as Italy, the Netherlands, Greece and Belgium.

"Unless governments take steps to regulate their economies, the invisible hand of the market will continue to promote obesity worldwide with disastrous consequences for future public health and economic productivity," said lead author Dr. Roberto De Vogli from the Department of Public Health Sciences at the University of California, Davis.

Patronizing independent food outlets, however, provided a different result. From the study:

The mechanisms explaining the influence of economic freedom on fast food and obesity have not been sufficiently studied. One possibility is that indiscriminate market deregulation favours global food chains at the expense of smaller farmers and local food systems. In effect, additional analyses showed that, while per capita transactions at chain food service outlets were positively and significantly correlated with mean BMI, this was not the case for per capita transactions at independent food service outlets.

Also, while the assumption may be that it was an increase in caloric intake or animal fat might have been responsible for the increase in BMI, the study came up with 'puzzling' results:

While the consumption of soft drinks explains a small proportion of the variation in the association between fast food consumption and BMI, the intake of animal fats and total caloric intake do not seem to be significant mediators of the association. This is puzzling. The fat and calories in fast food meals are usually blamed for the unhealthful effect of fast food.42 Although we cannot exclude the possibility of measurement errors, factors other than calories and fat content may explain why fast food makes people fat. Researchers need to investigate, for example, the metabolic effects of long-term exposure to fast foods produced from the meat of animals fed on corn, kept in confinement and exposed to excessive fertilization.

"This study shows how important public policies are for addressing the epidemic of obesity," said Dr. Francesco Branca, director of the Department of Nutrition for Health and Development at WHO.

"Policies targeting food and nutrition are needed across several sectors including agriculture, industry, health, social welfare and education," Branca said. "Countries where the diet is transitioning from one that is high in cereals to one that is high in fat, sugar and processed foods need to take action to align the food supply with the health needs of the population."

__________________