Worried about the economic and social costs of obesity, Japan has instituted a national law forbidding waist lines larger than 33.5 inches for men and 34.5 inches for women.

Under a national law that came into effect two months ago, companies and local governments must now measure the waistlines of Japanese people between the ages of 40 and 74 as part of their annual checkups. That represents more than 56 million waistlines, or about 44 percent of the entire population.

Violators are given nutritional guidance and “further education” if they are still overweight after six months of dieting. The law has prompted companies to adopt nudges.

With the new law, Matsushita has to measure the waistlines of not only its employees but also of their families and retirees. As part of its intensifying efforts, the company has started giving its employees “metabo check” towels that double as tape measures.

“Nobody will want to be singled out as metabo,” Kimiko Shigeno, a company nurse, said of the campaign. “It’ll have the same effect as non-smoking campaigns where smokers are now looked at disapprovingly.”

Smoking is not the only public health area where peer influences can be noticeable. Similar influences may shape the spread of obesity. Last year, a medical professor and a political scientist published a study in the New England Journal of Medicine the followed the spread of obesity among some 12,000 people from 1971 to 2003. You may have caught this in the news, but it’s worth taking a peek at this animated graphic (with audio) of how obesity spreads across this network of people. The clip last about two minutes.