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23 Aug, (foodconsumer.org) - That obesity brings an early death is a generally accepted fact. But two new studies in this week's New England Journal of Medicine say that even moderate weight gain increases the risk of premature death.
One study conducted over a decade-long period by researchers at the National Cancer Institute involved more than 500,000 U.S. adults. The study found that people who were just moderately overweight as they approached their 50s were 20 to 40 percent more likely to meet a premature death as compared to their normal weight counterparts.
"A substantial proportion of the population in the U.S. is overweight. So if overweight is related to premature death, that's very important to public health," said lead researcher Dr. Michael Leitzmann, an investigator at the National Cancer Institute. He added that people who are overweight have a moderately increased risk of premature death, and people who are obese have a greatly increased risk of premature death.
The study examined data on 527,265 men and women who were 50 to 71 years old in 1995 and 1996. The researchers followed up this group for the next ten years and calculated the risk of death for overweight and obese individuals.
Around 61,317 deaths were reported in the study sample as of 2005. Researchers found that people who were overweight when they were 50 had a 20 percent to 40 percent increased risk of early death, while obese people had thrice the risk of dying early as compared to people who had a normal weight.
"That translates into a 200 to 300 percent increase in the risk of premature death," Leitzmann said. "What we need to do is try to encourage people to maintain a healthy weight and avoid weight gain." But the researchers did not examine why the people died, meaning that the underlying cause of death remains unexplained.
However researchers did say that heart disease and cancer were significant causes of death in the study sample. The message from the study is simple. "People need to maintain a normal weight throughout adulthood and avoid developing excess weight," Leitzmann said. "And if you are overweight or obese, lose the excess weight."
The key point in the study is that it looked at the mortality of even slightly overweight people. Last year a study in the Journal of the American Medical Association found that being slightly overweight had no bearing on premature death. But one problem with arriving at such conclusions is that the study did not take into account confounding factors such as smoking and chronic illnesses.
Both these factors tend to skew up the results. In the current study researchers managed to take into consideration smoking and presence of chronic illnesses. Even so, they found that overweight people risk early death.
Among those who never smoked, but were overweight, the risk of death was 5 to 49 percent in men and 19 to 37 percent in women. Around 18.1% of all premature deaths among men in the study and 18.7% of women were attributed to overweight and obesity.
Writing in an accompanying editorial, Dr Timothy E Byers, of University of Colorado Cancer Center, Denver says that the study is a wake-up call to the so-called baby boomers. "Fortunately, evidence points to a substantial health benefit from even small changes in weight trajectory, so the achievement of an ideal body weight need not be the primary goal," he writes.
"There are many ways that physicians can help patients to make the critical first step of stopping weight gain. Small steps toward weight control, such as short bursts of activity and [subtle] changes in eating habits, need not require major lifestyle modification."
In the second study researchers at Yonsei University in Seoul, South Korea, and Johns Hopkins University examined 1.2 million Koreans ages 30 to 95 and followed them for 12 years. In the period, 82,372 deaths were reported and researchers attributed them to overweight and cancer.
"We saw some things that have been seen in other studies—a positive association of BMI with cardiovascular mortality, so the higher your BMI, the higher your mortality by CVD," said Dr Eliseo Guallar of Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.
"There were also positive associations with cancer beyond a certain level: at a BMI above 25 or 26, cancer mortality started to go up. And what we saw that is new is that there is an inverse relationship between respiratory mortality and BMI, so the higher the BMI, the lower the risk of respiratory mortality."
But it must be noted that Asians typically have a higher body mass than Americans. The diet and lifestyle differs a lot so, the percentage of body fat is more in Asian people. However Dr. Guallar said regardless of these differences, the fact remains that overweight and obesity are an invitation to early death.
The percentage of Americans who are overweight or obese has been on a steady rise over the last 25 years. Sedentary lifestyle practices are the main reason behind this problem, which has been termed as an epidemic by the World Health Organization. Obesity brings with it a lot of associated problems like type 2 diabetes, heart disease and cancer.
The Centers for Disease Control and Prevention says that a 5-foot-10-inch adult of either sex is classed as overweight if he/she crosses 174 pounds and obese at 209 pounds. For children the calculation also takes into account the age and sex and compares the weight with other children.
A report published in the April 5 issue of the Journal of American Medical Association had found that Americans were increasingly neglecting their health and were growing obese. The based on data from the2003-2004 National Health and Nutrition Examination Survey (NHANES) found that 32 percent US adults were obese, while 34 percent werr overweight.
The above studies prove that a large segment of the American population risks an early death. Dr. Meir Stampfer, chairman of the epidemiology department at the Harvard School of Public Health said the studies were statistically significant.
“They show quite convincingly, yet again, that overweight and, in particular, obesity, raise the risk of mortality,’’ Dr. Stampfer said. “It really should be the final word on this issue that’s arisen as to whether overweight is actually bad for you or not.”
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