A new study has suggested that those who lived longest are not necessarily people with normal weight, but overweight ones. The research was first published on January 2, 2013 in both Time.com and the Journal of the American Medical Association.
The findings were from the conclusions of a research that reviewed over 100 previously published research papers connecting body weight and mortality risk among 2.88 million study participants living around the world.
It discovers that obese people, and particularly those who are extremely obese, tend to die earlier than those of normal weight. However, the findings also indicate that people who are overweight (but not obese) have the tendency of living longer than people with medically normal body weight.
The study, described as the largest and most comprehensive review on weight, measured as body mass index (BMI), examined how it could influence long life.
“We published an article in 2005 that showed, among other things, that (being) overweight was associated with lower mortality — and we got an awful lot of negative feedback from that,” says the study’s lead author, Katherine Flegal, who is also a senior research scientist at the Centres for Disease Control and Prevention.
Flegal adds that since that study, many after it have arrived at the same conclusion, even if it was hard for researchers and the public to accept.
“I think there’s a lot of under reporting of this finding … and so people are sort of repeatedly surprised by it,” Flegal says.
Adding that many researchers do not expect to find a benefit connected with being overweight, she notes, they may not believe their results are valid if they find such a link, which may make them more cautious to publish them and invite review and discussion about what may be responsible for the trend.
According to the new study, Flegal and her team analysed every study they could find that broke down death risk broken by the standard BMI categories set by the World Health Organisation in the late 1990s.
In the study, underweight was defined as BMI less than 18.5, normal weight; BMI between 18.5 and 25; overweight; BMI between 25 and 30; and obese as BMI of over 30.
Also, men or women who are 5 feet 4 inches tall would have “normal” BMI if they weighed between 108 and 145 pounds, for example, and overweight if they weighed 146 to 174 pounds, and obese if it weighed more than that.
It states, ‘‘Overall, people who were overweight but not obese were 6 per cent less likely to die during the average study period than normal-weight people. That advantage held among both men and women, and did not appear to vary by age, smoking status, or region of the world. The study looked only at how long people lived, however, and not how healthy they were whey they died, or how they rated their quality of life.’’
The study’s findings further indicate that Flegal and her co-authors suggest that it is possible that overweight and obese people receive better medical care, either because they show symptoms of disease earlier or because they are checked more regularly for chronic diseases arising from their weight, such as diabetes or heart problems.
There are suggestions that there is also some evidence that heavier people may have better survival during medical emergencies such as infections or surgery. For instance, if you get pneumonia and lose 15 pounds, it helps to have 15 pounds to spare.
It also says that another possible explanation may involve “reverse causation”, suggesting that being thin does not make one sick, as some experts argue, but instead being sick can make you thin. The researchers argue that being overweight may be associated with longer lives if people who lose weight because of diseases such as cancer, for example, contribute to earlier death among individuals who weigh less.
The researchers add that their findings may necessarily be contrary to previous studies about the relationship between BMI and mortality because those analyses used a variety of different BMI categories with different cut-points for the various weight groups. In the new study, Flegal and colleagues only looked at research using the WHO categories.
Flegal observes that interpreting the results may be confusing, since the names of the WHO “normal” and “overweight” categories does not essentially match generally held perceptions.
They also note that doctors say weight alone may not be enough to understand an individual’s risk of developing disease and dying early.
The current research reveals, for instance, that it is not just the fat that follows weight gain, but the type of fat, especially fat that accumulates around the belly, that might be more life-threatening. In all, the results from the study indicate that the link between weight and health is a complicated one that may not be calculated basically in years lived.
But a consultant physician and cardiologist, University of Nigeria Teaching Hospital, Enugu, Dr. Benedict Anisuba, says fat itself is a killer.
He adds that certain diseases such as pneumonia is difficult to treat in people who are obese or overweight.
Anisuba adds, ‘‘Such a research should not even have seen the light of the day because it gives a conflicting report. Fat is a killer and there is nothing to be said about obesity. Nothing.’’