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Dr. Ayala

Dr. Ayala
Location
Philadelphia, Pennsylvania, USA
Title
V.P. Product Development
Company
Herbal Water
Bio
I’m a physician (Pediatrics and Medical Genetics), artist, and mother of 3 school age active kids. I recently co-founded Herbal Water Inc. (www.herbalwater.com) with my husband, Albert. I am a serious home cook, and love to entertain. My expertise is vegetarian food (I have been a vegetarian all my life). I strongly believe that eating healthy and enjoying good food go hand in hand. My main interests are science, nutrition and art, and I am overall a very curious person that tries to learn something new every day. Dr. Ayala (Ayala Laufer-Cahana M.D.)

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NOVEMBER 2, 2011 9:14AM

Can a genetic test tell if you’re going to become fat?

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Simple observation suggests overweight and obesity tend to run in families, and indeed the search for genes that affect the tendency to pack on pounds has found a growing list of genes that each contribute to overall risk.  The most famous of these genes is the FTO gene on chromosome 16 – the presence of specific “risky” versions of this gene is correlated with an extra 3 pounds for each risk-increasing copy (we have 2 copies of each gene).

But overweight and obesity are clearly influenced only partly by genetics and we can also explain the tendency for familial overweight by the fact that families often share eating and activity habits

It’s also clear that during the past three decades, while obesity rates have tripled, the genetic makeup of the population has not changed dramatically.  Therefore environmental factors (food intake and activity levels) are clearly responsible for this rapid rise in obesity.  The genetic makeup can only take responsibility for making some people more susceptible to these environmental factors.

Genetic testing of obesity

I love the field of human genetics: It uses math, biochemistry, probability and family stories to slowly reveal deep mysteries about who we are.  Studying our genetic makeup also holds enormous medical promise. 

Is genetic testing ripe for primetime? Most people in the field are humbled by the pace of discovery in genetics, and have a feeling we know less than we think we do.   Nevertheless, the growing interest in genetic assessment has already sprouted commercial companies that offer genetic testing directly to consumers.  The future is apparently already here, and these companies suggest not only that they can calculate your risk, but also that knowledge will empower better health decisions.

Since obesity is a really important contributor to disease, one of the risks these companies assess is one’s personal likelihood of developing obesity.  A company called deCODEme tests 11 variants in 11 regions of the genome known to increase an individual’s risk of being obese; 23andMe offers an obesity risk assessment based of 2 genes; all you need to do is spit into a tube (and part with a bit of money).  The results of these genetic screens are given as lifetime risk and relative risk compared to the average person.

Genetically discovering yourself – and then what?

Let’s say we’ve reached the point at which we can really tell who’s at greater risk for obesity, is this data worth knowing?  Would recognizing you’re at risk lead to risk reduction through a better diet, or rather to hopelessness and fatalism?

A new study in the journal Obesity examined the reactions to theoretical results of genetic testing for obesity risk in two groups of British respondents: 306 overweight and obese students, and 395 normal weight students.  The participants received a result that either told them their risk is average or that it’s above average.

In both groups, telling the individual that they were at higher risk for obesity led those people to anticipate they’d be more motivated to adopt a healthier lifestyle.  Again, this is a theoretical study, as no real genetic testing was done.  The study concludes that genetic testing “may offer an opportunity for behavior change if the feeling of “at-risk” can be linked to action by providing concrete information weight gain in conjunction with the test.”

We’re all at high risk

Even without personal genetic testing, I think most of us can estimate whether our risk for developing obesity is at or above par.  A quick survey of the genetic pool during family reunions, an honest look at one’s eating habits and at personal weight trend over time are quite informative.

Perhaps genetic testing can make the assessment just a tad more informed, but does it really make sense to assign risk for a condition that is so very common? Or does the knowledge, that in all western countries the majority of people develop overweight and obesity tell us all we need to know?

The best-case scenario – the result of “you’re at average risk for obesity” – predicts that there’s a pretty reasonable chance you might become obese.  The last few decades have proven that we all have a tendency to overeat when food is plentiful, tempting and calorically dense, we all tend to store the extras – a tendency that served our ancestors very well – and given the chance, we prefer watching TV to chopping wood.

And if knowing we’re at-risk may offer an opportunity for behavior change let’s announce it right now: We’re all at risk for obesity, each and every one of us, some even more than others.  So let’s all do something about it.

Dr. Ayala

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Comments

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I find this to be an open door to discrimination. Already insurance companies find ways to charge more or not cover those with existing conditions. Most people are quite aware of their propensity towards obesity.
Rita, that's definitely a potential downside of all genetic testing. Thanks for the comment.
Insurance companies don't need a genetic test. They ask your height and weight, which tells them the answer, probably far more accurately.

It's obvious to me that there are many, many genes controlling weight. There are genes controlling hunger and satiety, genes controlling metabolism, genes controlling how much your braid rewards you for eating something tasty, there are genes influencing how active/sedentary you are. Then there are habits and conditioning.

That they've found one gene is pretty meaningless.
Malusinka, I completely agree. I think personal genetics is in its infancy. The science is fascinating, but has minimal clinical applicability at this point.
I agree with rita. We don't want to become the movie Gattaca. The temptation to label people unfairly would most certainly arise. I don't see it as a potential downside. I see it as an absolute certainty. And, in light of all we do not know, it would be, at best, an extremely irresponsible situation to use genetic testing in this way, even with the best of intentions. Obesity isn't that complicated a problem in terms of knowing why. It's more complicated in fixing. The American diet is full of fat and sugar. Even canned vegetables have sugar added! As well, Americans do far less day-to-day walking. These two components, without even combining them with genetic factors, can be real problems in terms of long term weight gain. As well, Americans are encouraged to diet. Dieting should be a freaking four letter word! Eating less than a good intake of calories sends the body into a cycle where it holds onto the fat, and slows the metabolism. Pretty soon, you've got some poor schmuck eating 1500 calories a day and losing NOTHING. Because their metabolism is in the toilet. Plus, who can sustain that kind of caloric intake? Not many. Those are enough factors to determine obesity. The way of genetic testing opens the door to discrimination the likes of which we probably can't even imagine. Seriously. I get that it's exciting science. But it's not something we should use to determine future potential disease. The risk of misuse is just too great.
Not to be redundant but every single thing in your file at your doctors or hospital can be accessed by your insurance company and is routinely. They can ask you height and weight but with genetic testing they can gauge your risk of cancer and many other expensive diseases. Hundreds of people have access to your medical records now. I see it as another super intrusive way to charge more and deny coverage to more people. I never discuss anything with my doctor I don't first filter through with the knowledge my insurance company will be in on the entire matter. Voluntary testing is fine, but I can see where this will lead and it's not pretty.
I knew someone that had an enormous fat butt...

...I can assure you, it was all in her jeans.
I ask Smumey & Rita Shibr to jest behave.
This needs to be read by Michelle Obama.
I was giggling earlier. Gigglers save lives.
Employers don't need to know what's wrong with you. All they need to know is how much money your employer-provided insurance has spent on your or your family. That tells them all they need to know. The problems with tying health care to having the right job is that too many people don't/can't have the right job, and the employers who control the paychecks of people with the right jobs can easily discriminate based on your health. It turns out that hiring or retaining only experienced healthy people between 25 and 40 costs less.