But a new pill in the final stages of testing shows promise in attacking humanity's two biggest killers by helping people quit smoking and lose weight at the same time.
The drug, which could be available in a year or two, works by an entirely new approach — by blocking the same primeval circuitry in the brain that gives pot-smokers the munchies.
The development could offer a well-timed one-two punch against Americans' gravest health concerns. Smoking is the country's top killer, accounting for 435,000 deaths in 2000. The combination of poor diet, obesity and physical inactivity are right behind, with 400,000 deaths.
The gap between the two is substantially narrower than in 1990, when poor diet and inactivity caused 300,000 deaths, 14 percent, compared with 400,000 for tobacco, or 19 percent, says a report from the federal Centers for Disease Control and Prevention.
"This is tragic," said Dr. Julie Gerberding, CDC's director and an author of the study. "Our worst fears were confirmed."
"It's going to overtake tobacco" if the trend continues, Gerberding said. "At CDC, we're going to do everything we can to prevent it," she said. "Obesity has got to be job No. 1 for us in terms of chronic diseases."
As part of a Department of Health and Human Services campaign to try and get people to eat better and exercise more, two commercials were released Tuesday that use humor to try and convince people to change their habits, reports CBS News.
One 30-second as shows a man who turns in two "love handles" he has found to the lost-and-found at a mall. When he asks what they are, the attendant explains that they are "love handles" and adds, "lots of people lose them by taking the stairs." The ad ends with a graphic saying, "Take a small step to get healthy."
Another 15-second commercial shows a couple in the produce section of a supermarket. They find a double chin on the floor. The husband says that the owner "must have lost it snacking on fruits and vegetables."
Dr. Emily Senay says on The Early Show the message is for people to move more and eat less. She advises, "You have to eat high-quality food. If you fall into the obese category, talk to an expert. A lot of experts say that's not enough. The government needs to get more involved in regulating the food industry and in the toxic food environment that many experts believe we're living in. So a lot of things need to be done if we're going to turn this problem around. It's an incredible problem."
The researchers analyzed data from 2000 for the leading causes of death and for those preventable factors known to contribute to them. Like tobacco, obesity and inactivity increase the risks for the top three killers: heart disease, cancer and cerebrovascular ailments including strokes. Obesity and inactivity also strongly increase the risk of diabetes, the sixth leading cause of death.
The results appear in Wednesday's Journal of the American Medical Association.
Doctors who heard data on the new pill said that while better living habits should still be the foundation of good health, a new pill could be an important boost for those who cannot accomplish it through willpower alone.
"We tell people to diet and exercise, and that advice doesn't seem to be very effective," said Dr. Raymond Gibbons of the Mayo Clinic, who called the latest results "very provocative."
Two reports on the drug, called rimonabant, were released in New Orleans at a meeting of the American College of Cardiology. The research was financed by the drug's developer, the French firm Sanofi-Synthelabo, which plans to seek U.S. approval to sell it under the brand Acomplia after more studies are finished next year.
One study found the drug helped people drop 20 pounds in a year, while the other concluded it doubles smokers' success at quitting, at least in the short run. Doctors said the drug is likely to be marketed both for dieting and smoking cessation, but it is likely to be especially appealing to people beset by both problems.
Bob Berckman signed up to participate in a rimonabant study to kick a smoking habit he'd been trying to beat for 25 years, reports CBS News Correspondent Elizabeth Kaledin. All his previous attempts, until rimonabant, had failed.
"It really was seamless because the typical withdrawal symptoms I had experienced in the past, the anger and the anxiety, just weren't there," Berckman said.
And instead of gaining weight, as many people do after quitting smoking, Berckman told Kaledin he lost five pounds without even trying.
"We think this might be the ideal compound for people who are overweight and smoke," said Dr. Robert Anthenelli of the University of Cincinnati, who directed the smoking study.
In order, the leading causes of death in 2000 were: Heart disease, cancer, strokes and other cerebrovascular disease, chronic lower respiratory disease, unintentional injuries, diabetes, influenza and pneumonia, Alzheimer's disease, kidney disease, and septicemia.
The underlying preventable causes of death were, in order: tobacco, poor diet and physical inactivity, alcohol, microbial agents, toxic agents, motor vehicles, firearms, sexual behavior and illegal drug use. Together, these accounted for about half of all 2.4 million U.S. deaths in 2000.
An editorial accompanying the study in JAMA says national leadership and policy changes are needed to help curb preventable causes of death.
Doctors say the new drug rimonabant is noteworthy because it takes a fresh approach to helping people overcome their yen for food and tobacco. It is the first of a class of medicines that block the so-called endocannabinoid system.
Overeating and smoking can overstimulate this system, which in turn propels them to eat and smoke still more. By temporarily blocking the body's ability to receive these signals, experts believe they can return the system's working to normal.
In the larger of two studies conducted on rimonabant, Dr. Jean-Pierre Despres of Laval University in Quebec City enrolled 1,036 overweight volunteers, all with big potbellies that put them at especially high risk of heart problems. They were urged to cut 600 calories a day and randomly given either rimonabant or dummy pills.
After a year, those who got the higher of two doses of rimonabant had lost an average of 20 pounds and trimmed three inches from their waistlines. Nearly half of them took off 10 percent of their body weight. By comparison, those on placebos lost just five pounds.
Those getting rimonabant improved in other ways, too. Their levels of HDL, the protective good cholesterol, rose 23 percent, while their triglycerides fell 15 percent.
Despres said people taking the drug simply felt less hungry. In an earlier phase of the research, he could tell which volunteers were on the medicine by watching who passed up chocolate cake at the buffet table.
Anthenelli's study tested the drug for 10 weeks on 787 pack-a-day smokers who wanted to quit but could not. A longer follow-up will see how well they stay off, but in the short run, 28 percent shunned cigarettes for at least a month, compared with 16 percent on dummy pills.
Especially important, Anthenelli said, is that those on the drug gained little or no weight, and a third of the successful quitters actually took off pounds at the same time. Ordinarily, smokers gain six to 10 pounds when they quit.
Some people had minor digestive side effects at first, but they usually went away.
In all, seven large studies with rimonabant are in the works. They involve 6,600 volunteers who want to lose weight and 6,500 who want to quit smoking.