Genetics & Obesity – Prader-Willi Syndrome

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.


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.


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.


If you like what you see here, click here for updates


Related Posts



  1. I am glad that there is now stronger evidence that may explain some of these cases of grossly overweight children. And I agree with you that the lion’s share of the overweight don’t have this kind of genetics to explain their weight.

    That said, there’s a lot of gray area between having something like PWS and being a lazy fat slob who won’t put down his Starbucks Venti Mocha Frappucino.

    Valerie Taylor’s commentary in the Canadian Medical Association Journal ( and Yoni Freedhoff’s commentary in Public Health Nutrition ( are both recently published and provide different takes on some of the challenges with obesity.

  2. I agree – there’s a ton of gray.

    Too many people think that obesity is as simple as calories in vs calories out.

    It just really gets under my skin when faulty genetics are used as an excuse

  3. Maybe it’s not their genes, per se, but it’s possible it could be a hormonal imbalance. They may be hyperinsulinemic and they may have inherited a predisposition to diabetes from their parents, which is genetic. It’s conceivable the person you were talking to who was eating a lot of refined carbohydrates is secreting more insulin than your average person (although is the average person in the US now overweight?) and is losing calories to their fat tissue?

    These people don’t want to be fat, so why do they overeat? Are you saying it’s behavioral?

  4. TR,

    I agree that obesity and hormonal imbalances go hand in hand.

    And I agree that there is a predisposition for families to have diabetes run for generation after generation.

    But that doesn’t mean the cause is genetic. Poor dietary habits combined with an inactive lifestyle is being handed down from parent to child along with their dna. Which is the cause of the obesity & diabetes? One or the other or a combo of both?

    Thanks for the comment TR. I appreciate your point of view.

  5. Thanks for the response, healthhabits.

    I agree with just about everything you wrote.

    It’s also conceivable that poor dietary habits may cause an inactive lifestyle.

    Even though people appear to be overweight and have ‘energy to burn,’ you could argue that by their appearance alone, in a twisted way these people are starving. They are losing calories to their fat tissue and can’t mobilize the fatty acids for energy. So they don’t have the energy to be active.

    Fix the hormonal imbalance and perhaps you liberate the fat from the fat tissue and these people are now more compelled to move more.

  6. I am a few years late getting in on this conversation based on the date stamps I see but what the heck….
    Don’t lose sight of how type II diabetes begins…….a person chronically inundates their body with sugars and fats, then they arent doing any activity to utilize all that food…which then the body counteracts that by surging out the insulin to try and stabilize…….hence they are making the diabetic response happen…..good news is type II diabetes is completely reversable…..if the person begins eating the right food groups in the right amount and begins 4 hours of moderate exercise a week…..consistently…..their diabetes goes away.
    I have proven this dozens of times with clients that come to me all screwed up physically as well as educationally.

Comments are closed.