Preventing obesity   and smoking can save lives, but it doesn't save money, reported researchers. "It was a small surprise, for it is against the common belief," said Pieter Van Baal, who led the study. "But it makes sense. If you live longer, then you cost the health system more." The researchers found that from age 20 to 56, obese people racked up   the most expensive health costs. But on average, healthy people lived 84 years. Smokers lived about 77 years, and obese people lived about 80 years. Smokers and obese people tended to have more heart disease than healthy people. Therefore in the long run, the thin and healthy group cost about $417, 000, from age 20 on. Smokers cost about $326, 000 and obese people $371, 000. "The result throws a bucket of cold water onto the idea, based on guesswork, that obesity is going to cost trillions of dollars," said Patrick Basham, a professor of health politics. "If we're going to worry about the future of obesity, we should stop worrying about its financial impact," he said. "The benefits of obesity prevention may not be seen immediately in terms of cost saving in tomorrow's budget, but there are long-term gains," said Van Baal. "These are often immeasurable when it comes to people living longer and healthier lives." In the meanwhile, he said that governments should recognize that successful smoking and obesity prevention programs mean that people will have a longer chance of dying of something more expensive later in life. "Lung cancer is a cheap disease to treat because people don't survive very long. But if they are old enough to get Alzheimer's   one day, they may survive longer and cost more. We are not advising that governments stop trying to prevent obesity," Van Baal said. "But they should do it for the right reasons." What can we know about the belief that obesity costs much?
It turns out to be incorrect. It comes from scientific study. It is based on medical evidence. It has changed over the past years.
Question: Preventing obesity   and smoking can save lives, but it doesn't save money, reported researchers. "It was a small surprise, for it is against the common belief," said Pieter Van Baal, who led the study. "But it makes sense. If you live longer, then you cost the health system more." The researchers found that from age 20 to 56, obese people racked up   the most expensive health costs. But on average, healthy people lived 84 years. Smokers lived about 77 years, and obese people lived about 80 years. Smokers and obese people tended to have more heart disease than healthy people. Therefore in the long run, the thin and healthy group cost about $417, 000, from age 20 on. Smokers cost about $326, 000 and obese people $371, 000. "The result throws a bucket of cold water onto the idea, based on guesswork, that obesity is going to cost trillions of dollars," said Patrick Basham, a professor of health politics. "If we're going to worry about the future of obesity, we should stop worrying about its financial impact," he said. "The benefits of obesity prevention may not be seen immediately in terms of cost saving in tomorrow's budget, but there are long-term gains," said Van Baal. "These are often immeasurable when it comes to people living longer and healthier lives." In the meanwhile, he said that governments should recognize that successful smoking and obesity prevention programs mean that people will have a longer chance of dying of something more expensive later in life. "Lung cancer is a cheap disease to treat because people don't survive very long. But if they are old enough to get Alzheimer's   one day, they may survive longer and cost more. We are not advising that governments stop trying to prevent obesity," Van Baal said. "But they should do it for the right reasons." What can we know about the belief that obesity costs much?
A. It turns out to be incorrect.
B. It comes from scientific study.
C. It is based on medical evidence.
D. It has changed over the past years.
Answer: