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Obesity can be as bad as smoking

March 17, 2009 |  3:30 pm

Gross obesity can take 10 years off your life, as much as heavy smoking, and even being moderately overweight can take two to three years off, according to British researchers.

A team headed by Dr. Richard Peto, one of the world's leading experts on the health effects of smoking, and Dr. Gary Whitlock, both of the University of Oxford, analyzed 57 studies conducted in the United States and Europe involving 894,576 people, 61% of them male. During the course of the study, about 100,000 of the participants died.

The team correlated deaths to the body mass index or BMI, a commonly used measure of obesity that relates a person's weight to their height. A BMI of 25 or lower is considered normal, a BMI of 30 to 35 is considered moderately obese and a BMI higher than 40 is considered grossly obese. For a man or woman who is 5 feet 10 inches tall, a weight of 175 pounds gives a BMI of 25, a weight of 210 pounds gives a BMI of 30, and a weight of 280 pounds gives a BMI of 40.

The team reported today in the online version of the medical journal Lancet that every five-unit increase in BMI is associated with a risk of about one-third that of lifelong smoking. That is, people with a BMI over 30 have about one-third the added risk associated with smoking and are likely to have their lives shortened by two to three years. Those with BMIs over 35 have two-thirds the increased risk of smokers and are likely to lose five to seven years of life. And those with a BMI over 40 have the same increased risk as smokers and will likely lose eight to 10 years of life.

"Excess weight shortens human lifespan," Whitlock said in a statement. "If you are becoming overweight or obese, avoiding further weight gain could well add years to your life."

Moreover, Peto added, prevention is better than a cure. "In adult life, it may be easier to avoid substantial weight gain than to lose weight once it has been gained," he said. And "changing your diet but keeping on smoking is not the way to increase lifespan. For smokers, the key thing is that stopping smoking works."

The research, which was funded by Britain's Medical Research Council, the British Heart Foundation and Cancer Research UK, among others, will be published in the March 28 edition of the journal.

-- Thomas H. Maugh II