"The Effects of Obesity on the Immune System and Kidney and Liver Diseases"
In the ABCs of the health consequences of obesity,
I is for Immunity.
The SOS trial, which followed the fates of thousands of
bariatric surgery patients for a decade or two,
compared to a control group that maintained their weight,
and those who surgically lost about 20% of their body weight
not only lived longer, thanks in part to less diabetes
and less cardiovascular disease, but they also got less cancer.
This may be because anti-tumor immunity
appears to be affected by weight.
Natural killer cells are your immune system’s first line of defense
against cancer cells (as well as many viral infections),
and their function is severely impaired in obesity.
Randomize obese individuals to a weight loss program, though,
and there was a significant reactivation of their
natural killer cell function within just three months.
The program involved an exercise component, though;
and so, it’s hard to tease out the impact of the weight loss itself,
since physical activity alone can boost natural killer cell activity.
On the other end of the immune spectrum, obesity is suspected
to be a causal risk factor for the development of the
autoimmune disease multiple sclerosis.
This suggests obesity is associated with the worst of both worlds
when it comes to immune function:
underactivity when it comes to
protecting against cancer and infection,
but overactivity when it comes to certain
inflammatory autoimmune conditions.
J is for Jaundice. Thanks to the obesity epidemic,
nonalcoholic fatty liver disease is now the most common liver disorder
in the industrialized world.
Fat doesn’t just end up in our belly and thighs,
but inside some of our internal organs.
More than 80% of individuals with abdominal obesity
may have fatty infiltration into their liver,
and in those with severe obesity the prevalence can exceed 90%.
This can lead to inflammation, scarring, and ultimately,
cirrhosis and liver cancer.
Currently, this nonalcoholic fatty hepatitis is the leading cause
of liver transplants in American women,
and men are expected to catch up in 2020.
K is for Kidneys. Obesity is one of the strongest risk factors
for chronic kidney diseases.
Your kidneys compensate for the metabolic demands
of the excess weight by red-lining into what’s called
“hyperfiltration” to deal with the extra workload.
This resulting increased pressure within the kidneys can damage
the sensitive structures and increase the risk
of kidney failure over the long term.
What about L, M, N, O, P through Z?
If you want to continue through the alphabet,
the L could be for diminished lung function,
M for metabolic syndrome, and so on….
There’s even an X—for xiphodynia— pain at the tip of the bottom
of the breastbone from being bent forward by an expanding abdomen.
Given the myriad of health conditions associated with excess weight,
annual medical spending attributable to obesity is nearly
$2,000 per year, with obese workers with multiple conditions
costing companies up to $10,000 more in healthcare coverage
compared to lean counterparts.
This may actually account for some of the wage gap that
obese employees experience, as companies try to pass along
these costs beyond just brazen discrimination.
Between healthcare costs and diminished productivity
in terms of lost workdays, the total lifetime costs of obesity
for children and teens has been estimated to exceed $150,000.
Some estimates peg the national cost of obesity at about
$150 billion dollars with another $50 billion per year
added by 2030 as our increasingly
heavy baby boomers continue to age.
Others diametrically disagree, based on the morbid fact that
obese individuals may not live as long.
Just as the medical costs of tobacco- related diseases may be more
than offset by the shortened survival of smokers,
the lifetime health-care costs of obese individuals may turn out
to be lower because they are expected to die so much sooner.
So, the true cost may be more in lives, rather than dollars.
How much does being overweight cut your life short?
I’ll explore just that question next.