Feb. 25, 2009 -- Obese teens are just as likely to die before they reach old age as teens who are heavy smokers, while those who are overweight, but not obese, have the same risk for early death as lighter smokers, a new study shows.
Researchers followed 45,000 Swedish men from the time they were drafted into the military at the age of 18 until most were in their mid-50s.
They found that those who were obese in their late teens had nearly double the risk of dying during the almost four decades of follow-up, compared to those whose weight was normal at age 18.
This was a similar increase in risk as seen in men who smoked more than 10 cigarettes a day in their late teens.
Men who were overweight, but not obese, in their teens and did not smoke had a similar risk for early death as normal-weight teens who smoked one to 10 cigarettes a day.
The study appears in the latest issue of the journal BMJ Online.
"Most parents would warn their child about the dangers of even moderate smoking, but most probably wouldn't associate being overweight with the same level of risk," study researcher Martin Neovius, PhD, of Sweden's Karolinska Institute tells WebMD.
Obesity, Smoking, and Early Death
Normal weight in the study was defined as having a body mass index (BMI) of 18.5 to 24.9, while overweight men had a BMI of 25 to 29.9; obese men had a BMI of 30 or above.
Under this definition a 6-foot-2-inch person who weighs between 144 and 194 pounds is considered normal weight, while a 195- to 233-pound person is considered overweight; 234 pounds or heavier is considered obese.
In an effort to determine the early death risk associated with being overweight, obese, or a smoker in late adolescence, Neovius and colleagues analyzed data from a national military conscription register of Swedish men born between 1949 and 1951.
Because military conscription was compulsory in Sweden during this time, the registry represents a nationally representative sample of the country's males in their late teens at enrollment.
During an average of 38 years of follow-up, 2,897 of the roughly 45,000 men included in the study died.
The study also revealed that:
- Men who were obese at age 18 had a similar risk for early death as men who were heavy smokers but whose weight was normal in their late teens.
- Men who were obese and heavy smokers at age 18 were nearly five times as likely to die before age 60 as normal-weight, nonsmoking teens. Heavy smokers who were overweight in their teens were roughly three times more likely as normal-weight, nonsmoking teens to die young.
- Men who were very underweight in their late teens had an increased risk for early death that was similar to overweight men.
Implications for Public Health
Earlier studies examining whether being overweight, but not obese, in late adolescence increases the risk for early death have presented mixed findings.
In the newly reported study, being overweight was strongly linked to an increased risk for early death. Researchers from the Harvard School of Public Health came to the same conclusion in a study involving female nurses followed for many years.
In 2006, the researchers reported that women who were overweight at age 18 had an increased risk for death in middle age.
"More teenagers are overweight than obese, so this finding has very important implications for public health," Neovius says.
Carolyn Landis, PhD, who heads the Healthy Kids, Healthy Weight program at Cleveland's Rainbow Babies and Children's Hospital, agrees, but she adds that the problem is not limited to teens.
Landis tells WebMD that she sees children as young as 10 who already have type 2 diabetes as a result of being overweight or obese.
"I don't think people really understand how quickly obesity can impact your health," she says. "Many kids who are obese already have high blood pressure and other weight-related health problems when they enter school. As a society we need to take this issue much more seriously."