Do Heavier People Live Longer?
Weight and the Link to Mortality
The headline on Time.com was a shocker. It said, "Being Overweight Is Linked to Lower Risk of Mortality." The subhead went on to say, "The longest lived among us aren't necessarily those who are of normal weight, says a new study."
The story was about a study released in the Journal of the American Medical Association that looked at dozens of other studies, put all the data together and made what's called a "meta-analysis" or "study of studies." They looked at the "mortality risk among 2.88 million study participants living around the world." After combing through all the records they came to the startling conclusion that fatter people live longer.
Organizations around the globe grabbed onto the controversial conclusions and spread the news. It was a sensational headline, it sold a lot of papers and it made people feel better about being overweight.
Let me offer a little clarification. If you are obese, the study still said you're looking at a shorter life. But if you're just a little overweight, with a body mass index (BMI) between 25 and 30, the study said you're less likely to die than a normal weight person.
As Paul Harvey would say, here's the rest of the story.
Problem #1 - Smokers
The first problem with the study was that it didn't take out current or former smokers. Because smoking is an appetite suppressant, smokers tend to be slightly slimmer than average. Smokers also die, on average, at a much younger age from all the diseases caused by smoking.
For the last 30 years, well-done studies on longevity always put smokers in a separate category to properly account for the variables. Things like former smokers who relapse and are currently smoking, the number of cigarettes each smoker consumes in a month, even details like how deeply a smoker inhales can affect longevity.
Simply going through the studies used in the meta-analysis and removing the smokers would have shown that slightly overweight people are at a greater risk of dying. But there's more.
Problem #2 - Illness
The second problem is that the meta-analysis studies included people who had weight loss caused by diseases like cancer, diabetes, emphysema and other illnesses. It's common knowledge that people dealing with life-threatening illnesses often lose significant amounts of weight.
Including sick people in the study triggers something called "reverse causation." Being thinner isn't what made someone get sick and die. They got sick, they lost weight and then they died.
There's also the misconception that cancer is the only disease that causes you to lose weight. Illnesses like AIDS, congestive heart failure, chronic lung disease and chronic liver disease all can cause significant weight loss before death. David Katz, director of the Yale University Prevention Research Center put it best by saying, "If some of the thin people are sick, and they're thin because they're sick, that's going to make the health outcome of being thin look worse than it really is."
Problem #3 - Weight Over Time
The third significant problem is that the study didn't deal with a subject's weight over time. If the subject was normal weight at the time of death then that's what the study accepted as their average weight. What they should have looked at is average weight over time.
Thirty percent of all cancers are caused by excess weight. As cancer progresses, weight drops, muscle mass drops, strength drops, exercise drops and it continues in a downward spiral. At the time of death, the subjects weight may be significantly less than what was typical. But this study didn't factor that in. Being slim didn't cause the death, being overweight brought on the illness, which triggered weight loss and an early death.
Looking at studies that made these simple corrections, some involving tens of thousands of people, paint a very different picture. People who are overweight, even a little, are at far greater risk of dying sooner than people of normal weight. Next week I'll tell you just how dangerous that excess weight really is.
Just how dangerous are a few extra pounds? Click Here to find out.
UPDATE: 4/7/2017
In a major new study published in 2017 in the Annals of Internal Medicine, researchers showed that the more fat we put on, the more likely we are to die; especially from things like cancer, heart disease or respiratory disease. They demonstrated what we said four years before, the "obesity paradox" was nothing more than errors on the part of the researchers. As people put on excess weight, risks of death increased from 1-73% over a normal weight person.
Extra FAT does not help extend lives. Extra MUSCLE does.
UPDATE: 11/1/2017 - FAT but FIT isn't a thing.
Think you can be FAT but still FIT? A new study from the University of Birmingham says NO. Researchers analyzed the health records of 3.5 million people from 1995 to 2015. Researchers discovered that people who appeared healthy, but were technically obese, had a 50% higher risk of coronary heart disease than people who were within their ideal weight range.
In a statement to BBC.com researcher Ioanna Tzoulaki said, “Our study shows that people with excess weight who might be classed as ‘healthy’ haven’t yet developed an unhealthy metabolic profile, that comes later.”
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11/24/2013
Updated 4/7/2017
Updated 11/1/2017
