April 20, 2005 — -- Obesity may not be as deadly as we once thought. A new analysis of weight and mortality finds that the number of excess deaths each year attributed to obesity and being overweight in the United States is around 112,000 -- about one-quarter of the previous estimate of more than 400,000 deaths.
Last year, when scientists at the Centers for Disease Control and Prevention in Atlanta released the initial estimate of 400,000 obesity deaths, the figure came with a dire warning: Obesity was poised to overtake smoking as the No. 1 cause of preventable death in America.
However, other scientists questioned the methods used to calculate the 400,000 deaths and the CDC agreed to a recount. The new paper, published April 19, in the Journal of the American Medical Association finds that the relationship between weight and death is not as straightforward as previously believed.
Katherine Flegal, a senior researcher at the CDC's National Center for Health Statistics, and her colleagues determined that both underweight and obese individuals have an increased risk of death, but that there is no increased risk for moderately overweight people.
"I have been a critic of the 'obesity kills' statistics for years -- they assume all fat people die because they are fat," said Glenn Gaesser, professor and director of the kinesiology program at the University of Virginia in Charlottesville.
But Flegal believes her results are not meant to stand as a definitive answer on the issue of health and weight. "This is a piece of the puzzle," she said. "It is a contribution to the discussion."
In public discussions about weight and health, carrying a few extra pounds is often lumped together with obesity, but these new numbers suggest that overweight individuals do not have the same health risks as obese individuals.
"The most striking data here is the remarkably consistent finding, across all [government] surveys from 1970 through 2002, that the lowest mortality risk is found in the 'overweight' category," said Paul Campos, professor of law at the University of Colorado in Boulder and author of "The Obesity Myth." "Indeed, the excess deaths in the government's so-called 'ideal weight' category are quite comparable to those in the so-called 'obese' category."
Compared to normal weight individuals, overweight was associated with 86,000 fewer deaths. But obesity was associated with 112,000 excess deaths.
Obese is defined as having a body mass index greater than or equal to 30; overweight is a BMI of 25 to 29.9 BMI is a measure of body fat based on height and weight.
However, diet and nutrition experts are concerned this interpretation gives people the wrong message about healthy eating.
"People shouldn't think that this study gives them a free trip to the pork rind buffet," said Keith Ayoob, associate clinical professor in the department of pediatrics at Albert Einstein College of Medicine in New York.
Experts agree that a good diet and exercise are important for health, but some question whether the multibillion-dollar diet industry has misled Americans about the health hazards of being a few pounds overweight.
"I predict that this won't keep those who are desperate to defend the "fat kills" message from attempting to undercut this data," said Campos. There are "strong economic, social and political drivers, including pharmaceutical companies which are pushing ways to make people thinner."
But diet and nutrition experts counter that, while overweight itself might not be deadly, it can set you up for obesity in the future.
"The best predictor of obesity is being overweight," said Charles Clark, professor of medicine and pharmacology at Indiana University School of Medicine in Indianapolis. "The younger you are when you become overweight the more likely that you will become obese."
Diet and nutrition experts believe that focusing on mortality data obscures the true risk of being overweight, which is the toll it can take on a person's quality of life. Obese individuals may not die from their weight, but they often have problems like diabetes or high blood pressure.
"Keeping people alive is one thing. Keeping them feeling good and able to participate comfortably in life is another," Ayoob said.
Flegal would agree. Nothing in the data suggests anything about a decrease in health problems associated with obesity, she said.
Indeed, a second study in JAMA this week reinforces the point that obesity must often be offset with the use of drugs or other medical treatments. An examination of national data from 1999-00 finds that 16 percent of normal weight individuals were receiving treatment for high blood pressure compared with 39 percent of obese individuals.