Health Habits

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Posts Tagged ‘hypothalamus’

Genetics & Obesity – Prader-Willi Syndrome

December 23rd, 2009

A few days ago, I met a woman whose young child has been diagnosed with Prader-Willi Syndrome.

And while I am no expert on Prader-Willi, I have a general idea of the associated symptoms.

These include:

low levels of testosterone
sleep disorders
strabismus (mis-aligned eyes)
scoliosis
delayed puberty
weak muscles
extreme flexibility
learning disabilities
various

and an insatiable desire to eat which leads to compulsive overeating, morbid obesity and an increased risk of diabetes and various other obesity related conditions

The cause of PWS is genetic.

Although the exact genes responsible for Prader-Willi syndrome haven’t been identified, the problem is known to lie in a particular region of chromosome 15.

This defect in chromosome 15 leads to a malfunctioning hypothalamus.

This results in a flaw in the hypothalamus part of their brain, which normally registers feelings of hunger and satiety. The number of oxytocin neurones–the putative satiety neurones–in the hypothalamic paraventricular nucleus is markedly decreased in Prader-Willi syndrome. This is presumed to be the basis of the insatiable hunger and obesity of patients with the syndrome.

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This means that people with this flaw never feel full; they have a continuous urge to eat that they cannot learn to control. To compound this problem, people with PWS need less food than their peers without the syndrome because their bodies have less muscle and tend to burn fewer calories.

Doesn’t sound very nice, does it?

So, maybe that explains my irritation the very next day when I had a chat with someone who told me that the reason they are fat is their genetics. His mom is overweight and so is his father.

Never mind that he was drinking a Starbucks Venti Mocha Frappucino and munching on some sort of scone while we had this brief conversation.

Arrrrgggghhhhh

So, like the shit-disturber I am (pardon my French), I asked him if he suffered from Prader-Willi or some other form of genetic disorder.

[blank stare]

The moral of the story….the next time you are feeling sorry for your obviously fat genetics, think about the little guy in that Prader-Willi video….feeling hungry all the time.

If you’re overweight, odds are it ain’t your genetics.

And if it ain’t your genetics, you can do something about it.

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Binge Eating: Is Your Brain Making You Fat?

October 10th, 2008

Researchers from the University of Wisconsin-Madison have discovered that “overeating throws critical portions of the brain out of whack, leading to a malfunctioning hypothalamus, metabolic inflammation, insulin resistance, leptin resistance, obesity and type 2 diabetes”.

The study, published in the October 3 issue of Cell, attempts to expand on previous research which showed that over-nutrition is associated with chronic inflammation in metabolic tissues.

Specifically, they wanted to see whether metabolic inflammation compromises the brain’s metabolic regulatory systems and therefore promotes over-nutrition associated diseases.

Translation:

They wanted to see if a trip to the “All You Can Eat Buffet” would mess with your brain, causing an impaired metabolism and increased obesity.

The Results:

A trip to the “All You Can Eat Buffet” will mess with your brain, causing an impaired metabolism and increased obesity.

The Details:

There is a substance in your brain called IKKβ/NF-κB.

IKKβ/NF-κB is a mediator of metabolic inflammation. Most of the time, it just sits there, inactive.

However, a single session of overeating activates the IKKβ/NF-κB found in your hypothalamus.

Once activated, the IKKβ/NF-κB increases inflammation in your metabolic pathways and interrupts the normal signaling of the obesity regulation hormones, leptin and insulin.

When this happens over and over and over again, your body becomes resistant to insulin and leptin.

And you become fat.

And if that wasn’t bad enough, the increased obesity leads to even more inflammation. Which leads to more leptin / insulin resistance and so on and so on.

This all results in quite the little vicious circle of inflammation, hormone resistance and obesity.

Conclusion

The researchers have concluded that “their findings could lead to treatments that might stop this cycle before it gets started”.

If they can inhibit the IKKβ/NF-κB pathway in the hypothalamus, they may be able to eliminate the inflammatory response to over-eating and the resultant hormone resistance and obesity.

They also noted that “if realized, such a strategy would likely offer a safe approach given that the critical pathway appears to be unnecessary in the hypothalamus under normal circumstances.”