I think the article may be badly translated or misleading. Since I live in Japan, I know a bit more about the way things tend to work. The English makes it seem as if any individual company will have to pay 10% more if its particular group of employees don't lose weight, but I think they're actually talking about payments on a country-wide scale. If, in general, all companies don't encourage employees to lose weight, everyone will have to pay 10% more into funds for elderly health care because they anticipate increased costs due to health problems related to increased weight among those who will retire after 2012.
It's all a crock anyway because the Japanese medical system will need more money to support the population of people who are elderly. The retirement age in Japan, a country with the longest life span in the world, is 60. Most people live 20-25 years beyond retirement and they run to the doctor every time they stub a toe. That may sound like an exaggeration, but trust me, it is not. The Japanese don't trust themselves to diagnose a sneeze or a headache with OTC medication. In fact, the system is so screwed up that it costs less to go to a doctor and be given an aspirin by him than to buy a bottle at a drug store.
So, this is just a way of setting up employers to start paying more money into the system which is going to be unsustainable in the future with the low birth rate (1.4 children per couple) and long lifespan (average expectancy is 83, I think). There simply aren't enough tax payers. Even if they comply and employees lose the weight, they're all still going to be paying more. They'll just come up with a new excuse why they have to pay more.
At present, companies pay 50% of the social medical insurance and employees the other 50%. This is just an excuse to prop up the socialized medical system (which is still better than private insurance in the U.S., but widely abused), but it will probably make a lot of people who are at a healthy weight just go too far and get even thinner due to social pressure. Either that or even more people will be offing themselves by jumping in front of trains. Now they'll be doing it because their waist size is too big.
That being said, at least the Japanese approach isn't punitive toward the people at this point. They try to counsel people and get them help rather than threaten them with taxes or increased personal health insurance premiums.
As an aside, let me note that Japan has more debt per capita than the U.S. and part of it is the health care system which gives people a ridiculous amount of unlimited coverage, particularly to those with children or who are elderly. While I absolutely support national health care, I think that the Japanese have taken it to an extreme. People shouldn't be running to a doctor every time they get a sniffle, menstrual cramps or a headache.