Aliquot

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aliquot

aliquot
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December 31
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Dr.
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Neuroscience Ph.D. ************************** Passionate about science education and outreach; enjoys a great discussion about the intersection of science and everyday life *************************** Currently a biomedical researcher at a Harvard University hospital - Areas of expertise: endocrinology, appetite and metabolism, neuroscience, biochemistry, molecular biology *************************** Areas of interest: science and art, science and society, science policy, books/films/music, reading great magazines, travel, learning new things and sparking new ideas, gardening/nature *** All Content Copyright Aliquot - do not reproduce without express permission ***

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OCTOBER 27, 2009 11:18AM

mild obesity may not be death risk after all

Rate: 8 Flag

Body fat is essential for life. 

White fat, or the lipid-storing depots found under our skin and around our organs, serves an important energetic and homeostatic role.  Dozens of hormones and other factors are secreted from our fat tissue into the circulation, where they serve important physiological roles. Recent studies have also shown white fat to be important for immune function. 

Brown fat, or the thermogenic (calorie-burning) fat, was recently identified in adult humans, although previously scientists had believed it was only found in babies (Identification and importance of brown adipose tissue in adult humans.  Cypess AM, Lehman S, Williams G, Tal I, Rodman D, Goldfine AB, Kuo FC, Palmer EL, Tseng YH, Doria A, Kolodny GM, Kahn CR.  N Engl J Med. 2009 Apr 9;360(15):1509-17).

These facts are not disputed.  However, the correct or optimal or 'best' amount of body fat for humans to have, is still  hotly-contested.

 See these two recent findings:

 From Doehner et al. 2009, you can see that BMIs considered overweight or mildly obese are actually NOT correlative with higher risk for mortality:

 

 

BMI mortality

 

Another recent publication has come to an important clinical agreement in terms of diagnosing the metabolic syndrome - the cluster of metabolic phenotypes (including obesity) which lead to greater health risk.  The most important finding is that obesity should not be considered an obligatory component of the diagnosis:

"A cluster of risk factors for cardiovascular disease and type 2 diabetes mellitus, which occur together more often than by chance alone, have become known as the metabolic syndrome. The risk factors include raised blood pressure, dyslipidemia (raised triglycerides and lowered high-density lipoprotein cholesterol), raised fasting glucose, and central obesity. Various diagnostic criteria have been proposed by different organizations over the past decade. Most recently, these have come from the International Diabetes Federation and the American Heart
Association/National Heart, Lung, and Blood Institute. The main difference concerns the measure for central obesity, with this being an obligatory component in the International Diabetes Federation definition, lower than in the American Heart Association/National Heart, Lung, and Blood Institute criteria, and ethnic specific. The present
article represents the outcome of a meeting between several major organizations in an attempt to unify criteria. It was agreed that there should not be an obligatory component, but that waist measurement would continue to be a useful preliminary screening tool. Three abnormal findings out of 5 would qualify a person for the metabolic syndrome. A single set of cut points would be used for all components except waist circumference, for which further work is required. In the interim, national or regional cut points for waist circumference can be used."
(Circulation. 2009;120:1640-1645.)

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I've been meaning to write something about the new guidelines for metabolic syndrome. I find it interesting that what the general public associates with obesity (i.e. BMI) isn't really an indicator of it at all - obesity is a weight over what is healthy for the individual, but some people just carry a little extra harmless fat and aren't obese at all. A bit of a dilemma as far as diagnosis and weeding out risk factors in the clinic, but very interesting from a physiological point of view.
I agree! Body weight has to be one of the more misunderstood biological concepts in the general public - there is so much misinformation being written (and sold!) that its hard for scientists to keep up with the clarifications!
I've just read three of your posts one after another, and just want to thank you for the valuable information they provide.

I also must compliment you on your writing skills. Your science is precise yet very easy to comprehend, even for a artsy-fartsy like myself.

My field is in communication and I have for some time recognized the suspicious ways in which psudoscientific health products are sold. Today, the lexicon of science is used to make snake oil more attractive, much like religious and magical pronouncements were used to the same effect in earlier times.

Another example of this is how New Age gurus who have no training in physics use quantum mechanics to sell their brand of spirituality.

I look forward to seeing you eventually on Oprah, busting some of the myths she herself may have propogated.
ruicanuck -
Thank you so much for your kind words. Am glad something on here has been useful for you - as that is my goal!
As for this comment:
"Another example of this is how New Age gurus who have no training in physics use quantum mechanics to sell their brand of spirituality."
Are you referring to the fake-documentary 'What the bleep do we know?'
If so, am so glad you're aware its a bunch of BS. I'll have to make a separate post about that dangerous film. One of the 'scientists' in that film calls himself a neuroscientist, but after a bit of digging I discovered he is a chiropractor with no advanced degrees, specialized training, or expertise!
Thanks again for your feedback!!
A.
This is all just pesudoscientific nonsense. Fat people have lived very long, healthly lives, as have skinny folks.
We all know that only one thing controls when you die.
Techno-Bast, God's alter-ego.

Oh and Rated.
Yes, by all means, please write on What the Bleep.... I would be most interested in reading what you have to say.

That is the most blatant example of what I am talking about, but there are many, many others. The Web is full of snake oil salesmen dressed in lab coats.

I actually meditate daily and practice internal martial arts, so am a big advocate of sprituality. I also believe there are ways to approach such practicies scientifically and rationally. However, this does not suddenly make non-scientists qualified to preach on a precise discipline like subatomic physics. I think that is an insult to both the field of science and the practice of sprituality.
Metabolic, schmetabolic. In Oklahoma, we just call it "good living."
Andy - thanks for grounding us all with your rational comments, as usual :)

ruicanuck - I think you'll find a lot of scientists who would agree with you that spirituality and science should be kept separate, but one is not necessarily more important than the other for someone's well being.

Steve - Good Living, you got it!

WalkAway - thanks for your comments. You're completely right. I know plenty of skinny folk who are either malnurished or have eating disorders (although not all thin people are unhealthy of course). However, the stigma in society is always on people who are not thin, unfortunately. Extremes are usually where the problems arise in science - in this case the extremes are too thin or too overweight, as you can see from the graphs above.