Health Habits

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Posts Tagged ‘hunger’

The Ghrelin Made Me Eat It

December 28th, 2009

You feel hungry.

You eat.

You feel full

You stop eating.

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This is how it’s supposed to work.

Unfortunately, our bodies don’t always work the way we want them to.

Sometimes,we feel an intense desire to eat (and eat and eat) even when we are full

And why is that?

According to researchers, one of our appetite hormones – Ghrelin, can trick our brains into making us eat “pleasurable” foods even when we are full.

Previous research has shown that elevated levels of ghrelin is linked to the “reward” aspects of eating.

According to researcher Dr. Jeffrey Zigman, rewards can “generally be defined as things that make us feel better”.

“They give us sensory pleasure, and they motivate us to work to obtain them,” he said. “They also help us reorganize our memory so that we remember how to get them.”

In this recent study, researchers looked for an answer to why someone who is already is driven to eat that high-calorie dessert.

For this study, the researchers conducted two standard behavioral tests on some lab mice.

In the first, they evaluated whether the mice that were fully sated preferred a room where they had previously found high-fat food over one that had only offered regular bland chow. They found that when mice in this situation were administered ghrelin, they strongly preferred the room that had been paired with the high-fat diet. Mice without ghrelin showed no preference.

“We think the ghrelin prompted the mice to pursue the high-fat chow because they remembered how much they enjoyed it,” Dr. Perello said. “It didn’t matter that the room was now empty; they still associated it with something pleasurable.”

When the researchers blocked the secretion of ghrelin, the mice spent less time in the room that they associated with the high-fat food.

For the second test, the team observed how long mice would continue to poke their noses into a hole in order to receive a pellet of high-fat food. “The animals that didn’t receive ghrelin gave up much sooner than the ones that did receive ghrelin.”

Note

Humans and mice share the same type of brain-cell connections and hormones, as well as similar architectures in the so-called “pleasure centers” of the brain. In addition, the behavior of the mice in this study is consistent with pleasure- or reward-seeking behavior seen in other animal studies of addiction.

Future research will look into which neural circuits in the brain regulate ghrelin’s actions.

Conclusion

Elevated levels of ghrelin can force your brain to override your normal signals of fullness.

So, the next time you overeat when full, blame it on the ghrelin.

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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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