European health ministers from 53 countries approved the world's first charter to fight obesity on Thursday, vowing greater action against the epidemic of expanding waistlines across the continent.

The charter, approved in Istanbul, Turkey, was drafted by the World Health Organization in consultation with its European member states. It is the first real attempt to compel national authorities to take concrete action to combat obesity.

"Lots of governments have good recommendations and nice guidelines, but in terms of nutritional goals, most countries haven't achieved them," said Dr. Francesco Branca, WHO's European adviser for nutrition and food security. The charter commits governments to things like improving the availability of healthy foods and adopting regulations for safer roads to promote cycling and walking.

The prevalence of obesity in Europe has tripled in the past two decades; half of all adults and 20 percent of all children are overweight. Being overweight or obese increases the likelihood of diseases such as diabetes and cancer, and shortens life expectancy. Obesity is also responsible for up to 6 percent of all health care costs across Europe.

The WHO charter aims to curb the epidemic in the next five years, and hopes to reverse the trend by 2015.

Still, Branca admits that putting Europe-wide policies into place that tackle issues as diverse as improving national dietary guidelines and urban planning, to allow for more regular physical activity, will take some time. With countries being overrun by fast food chains and a decreasing number of people exercising regularly, experts say that the European environment has become conducive to an unhealthy lifestyle.

The problem is particularly acute in children. Overweight and obese children are likely to remain so into adulthood, leading to the early onset of related diseases. "The charter represents a major turning point in addressing the challenges of childhood obesity," said Prof. Phillip James, president-elect of the International Association for the Study of Obesity.

One of the charter's more contentious inclusions is an obligation for the private sector to limit the marketing of fatty, sugary foods to children. It calls for specific regulatory measures to "substantially reduce" the advertising of unhealthy foods to children.

The clause implies that governments should introduce legislation regarding marketing to children, with an eventual move to adopting an international code of practice. In the past, the food industry has fought against such regulation, since it may eat into their profits.

Across Europe, there are marked policy differences in advertising to children. Norway and Sweden have banned the practice. In contrast, in the Netherlands, Portugal, and Spain, food and drink industries engage in self-regulation.

To some experts, advertising unhealthy foods to children crosses the lines of fair business play. "The commercialization of children must stop," said James, who was reassured by the inclusion of the marketing clause in the charter. "This signals that we haven't done enough to protect children from the advertising environment, and now need to move decisively."

While the numbers are grim, with 150 million adults and 15 million children expected to be obese by 2010, rapid action now might yet control this epidemic, experts say. "Everyone says it takes a generation to reverse this, but it doesn't," argues Branca. The dramatic spike in obesity, he says, has only occurred in the past decade. "If we work together now, we might be able to change the obesity trend at the same speed at which it happened."