"What’s the Ideal BMI?"
We seem to have become inured to the mortal threat of obesity.
If you go back in the medical literature a half century or so
when obesity wasn’t just run-of-the-mill,
the descriptions are much more grim:
“Obesity is always tragic, and its hazards are terrifying.”
But it’s not just obesity. Of the 4 million deaths every year
attributed to excess body fat, nearly 40% of the victims
are just overweight, not obese.
According to two famous Harvard studies, weight gain
of as little as 11 pounds from early adulthood through middle age
increases the risk of major chronic diseases,
such as diabetes, cardiovascular disease, and cancer.
The flipside, though, is that even modest weight loss
can have major health benefits.
What’s the optimal BMI?
The largest studies in the United States and around the world
found that having a normal body mass index, a BMI from 20 to 25,
is associated with the longest lifespan.
Put all the best available studies with the longest
follow-up together and that can be narrowed down even further
to a BMI of 20 to 22. That would be about
between 124 to 136 pounds for someone who stands five-foot-six.
You can pause the video here to use this unisex chart
to see what your optimal weight might be based on your height.
But, even within a normal BMI, the risk of developing
chronic diseases, such as type 2 diabetes, heart disease,
and several types of cancer starts to rise towards the upper end,
even starting as low as a BMI of 21.
A BMI of 18.5 and 24.5 are both considered within the normal range,
but a BMI of 24.5 may be associated with twice
the heart disease risk compared 18.5.
Look at this diabetes graph among women, a five-fold difference
in diabetes rates all within the so-called ideal range under 25.
Just as there are gradations of risk within a normal BMI range,
there is a spectrum within obesity.
Class III obesity, a BMI over 40, can be associated
with the loss of a decade of life or more.
At a BMI greater than 45, such as a five-foot-six person
at 280 pounds, life expectancy may shrink
to that of a cigarette smoker.
There are, however, so-called “obesity skeptics”
that argue that the health consequences of obesity are unclear
or even greatly exaggerated. They are a motley bunch,
ranging from feminists, queer theorists, and new ageists
to “far right wing, pro-gun, pro-America websites
where the idea [is] that obesity alarmists are nanny-state
communists who simply want to stop us from having fun….”
Unlike activists who, for example, organized to raise
consciousness and stamp out the AIDS epidemic,
the size acceptance movement appears to have the opposite goal,
rallying for less public awareness and treatment of the problem.
(They do have good slogans though:
“We’re here, we’re spheres, get used to it!”)
I’m all for fighting size stigma and discrimination—
I have a whole section on weight stigma in my new book—
but the adverse health consequences of obesity
are an established scientific fact.
Can’t you be fat but fit?
In a study of more than 600 centenarians
(those living over 100) only about 1% of the women
and not a single one of the men were obese.
But there does appear to be a rare subgroup of obese individuals
who don’t suffer the typical metabolic costs
such as high blood pressure and cholesterol.
This raises the possibility that there may be such thing as
“benign obesity” or “healthy obesity.”
It may just be a matter of time, though,
before the risk factors develop.
And even if they don’t, followed long enough,
even quote-unquote “metabolically healthy” obese individuals
are at increased risk of diabetes, and fatty liver disease
and cardiovascular events such as heart attacks,
and/or premature death.
Bottom line: there is strong evidence
that so-called “healthy obesity” is a myth.
Many “fat-activists” try to downplay the risks of obesity,
even as they may be among the epidemic’s greatest victims.
Lynn McAfee is the director of medical advocacy
for the Council on Size and Weight Discrimination
and routinely takes part in obesity conferences
and government panels on obesity.
“I’m not actually particularly that interested in [health],”
she is quoted as saying, “and God I hate science.”