February 11, 2008

Childhood Obesity: Nature or Nurture?

[By Crabby]

Cranky Fitness is confused.

So there was a study that came out last week on the heritability of childhood obesity. The study looked at how much of childhood obesity is genetic, versus how much has to do with lifestyle stuff.

You know, like eating Pop Tarts and Dunkin' Doughnuts for breakfast instead of oatmeal and blueberries. Or playing video games and watching Survivor instead of going outside to play wholesome games like "Kick the Can" or "Capture the Flag" or "Jump Off the Roof with a Grocery Bag Parachute" or "Nearly Set the Neighbor's House on Fire Playing With Matches."

(Younger readers might not be aware that in the old days, we Baby Boomers were often permitted to play outside for hours and hours at a time, completely unsupervised. Isn't that neat? We tended to be slimmer, those of us who actually survived.)

Anyway, even though the study didn't get that specific, the general conclusion was: fat kids are mostly screwed because of their genes, not because of how their parents are raising them.

A few observations, then I'm eager to hear what you all think.

1. This was an extremely depressing study.

Not just because of the poor fat kids, but also because I could NOT make any sense out of it. I'm hoping an actual scientist might take a look, because it seemed to be saying a lot of contradictory things all at once. I can usually at least follow along a little bit when I read research studies, but this one made me feel dumb. I think it may have said that being a fat kid is about 77% genetic, but, well, don't quote me on that.

2. People Are Going to Believe What They Already Think is True.

Many who report on this study simply go with the headline and proclaim that "Nature Tops Nurture" when it comes to obesity, so Don't Blame the Parents. Others read the same study and come to the opposite conclusion.

At Mark's Daily Apple, for example, where the Impressively Healthy hang out, they noted that there is still a big environmental influence on how genes get switched on and off. If you drop down into the comments section, the general tenor is very academic, and the conclusion seems to be: screw the headlines, it's still mostly Nurture, not Nature.

3. I Think it's Both Nature and Nurture.

4. So Don't Leap to the Conclusion That Any Particular Fat Kid has Unusually Bad Health Habits.

If 77% of obesity is indeed genetic, there are some kids who are going to be fat doing the exact same stuff the skinny kids are doing. To stigmatize them and blame their parents without actually knowing anything about their particular diet or exercise habits is counter-productive and really mean.

Back when I was growing up, there were fewer obese kids--but those who were, in my experience, weren't doing anything all that different from the rest of us. To pretend we all have the same metabolisms and that all skinny people are virtuous and all fat people are lazy is just silly.

5. But As a Society, We Feed Kids Too Much Crap and Don't Ensure They Exercise Enough. That Needs to Stop.

Genes don't change over a couple of generations. The obesity epidemic is a real problem, and it wouldn't be here all of a sudden unless something major changed in the way we're eating and exercising.

So since we can't change individual genes (yet), we have to do all we can to make sure all kids are learning healthy habits. The ones who are genetically lucky enough to be a healthy weight despite eating crap and not exercising enough will still pay for it later in life. No one can afford to grow up thinking that unrestrained scarfing of junk food and a sedentary lifestyle are "normal," let alone some sort of entitlement.

End of Sermon.

So what do you folks think about the Nature vs. Nurture debate as far as childhood obesity?


  1. It is confusing. I think when headlines say "fat is genetic" they should trouble themselves to be a bit more specific and say that a tendency towards obesity is genetic. Otherwise it sounds like if you have that gene, you're doomed, kid, doomed.

    When I was growing up, back in the early neolithic period, I only knew one girl who was truly obese. And she was active, but she was still much larger than anyone else.

    I'm still putting the rise in obesity down to diet, e.g. high fructose corn syrup, more than anything else. Well, plus that other factor you mentioned -- today parents keep the kids inside if you can't supervise them playing outside. I lived for a couple of years next to a large park with a large playground, but except on weekends I only shared it with other adults who were being walked by their dogs.

    What worries me is that study about parents who don't notice if their child is obese.

  2. I'm with you, Crabby, I think it's a mixture of both. But there's no question that most kids aren't able to be as active as we were. There's no way in hades I'm gonna let my kids play outside unsupervised, for their safety, and that of the neighborhood!
    They still manage to be quite active, and chasing them up and down the three flights of stairs in our townhouse keeps ME active, as well. (We thought about buying a ranch-style house, but then where would I get my exercise?)

  3. The Bag Lady suffered the stigma of being a skinny child. Seriously skinny. Stick thin. Teased about it constantly. She grew tall faster than she filled out. Her best friend was short, and chubby. What a pair we were.
    We were inseparable, and did all the same things and ate all the same things. Genetics HAD to be playing a part in that.
    Nowadays, however, children are less active, and it shows. There are definitely more overweight children now than there were then. There are definitely more fast food restaurants, and mothers who work and are too tired to actually cook a meal when they get home from work. There are also more packaged 'convenience' foods on the market.
    There simply has to be a connection there.
    Is 'convenience' killing us slowly?

  4. Hi Crabby,

    This is my observation. I was a fat kid. As a mother, I was very careful about my kids exposure to food and exercise. (I still get teased about the veggies instead of cupcakes packed in their lunches.)

    The result is that, as adults over tha age of thirty-five, they are both well within normal weight ranges. The better news is that, at this point in their young lives, my five grandchildren are all within normal weight ranges.

    Let me quote my daughter when she was in seventh grade. Another girl, who was significately overweight said to my daughter: My mother is fat, and I'm fat, Your mother is fat and you aren't. How come?

    My daughter pointed out the difference in their lunches (both brought from home. No school cafeteria.) My daughter had a sandwich, apple and some cucumber slices. The other girl had a thermos of soup, a sandwich, fruit and a package of dessert cakes.

    The problem is that parents give children adult-sized meals and also use food to comfort, quiet and appease.

    Since I am a grandma, I am required to provide treats, and I do: assorted berries, bananas, cantaloupe, and those cookies that come in 100 calories a package. (Much better than a 250 calorie donut.) I think the 100 calorie cookie packs are becoming popular with children because they now come in alphabet and chocolate animal crachers as well as in traditional cookies and a number brands are selling them. They are expensive but worth it for calorie control,


  5. I was always a chubby kid, but I know it is because I learned very early on that I dealt with things by eating. My sister and I were home alone after school from a very young age. I would fill the time with eating. My mom didn't keep a bunch of junk in the house, I would just eat A LOT. I also kept a stash of candy under my bed whenever I could.

    It definitely seems like parents are afraid to say no these days. It also seems to be increasingly popular to think that other people are supposed to raise and discipline your children for you. However, I do think it is NUTS to have so much junk food readily available to kids at school.

  6. I read something interesting (I think it was in Fast Food Nation, but my monday morning memory isn't too sure) that the mother's diet while the kid is in the womb also plays a big part. Both whether the mother ate too much bad food, and if she didn't eat enough at all (in the latter case, the mother not eating enough turned on a gene in the baby to store fat because it thought there was famine going on or something). So genetics and nourishment in the womb definitely have an impact.

    But there's no way that we can chalk it all up to that (seriously, 77%?). I was overweight in high school - I didn't exercise, I watched tv all day when I wasn't in school, and I regularly stopped at the convenience store after school to consume whole bags of milano cookies. Now, I suppose I can chalk it up to my genes that I wasn't grossly obese on that diet (I did have relatively healthy meals for dinner every night), because I know other people doing the same thing would be.

    But now, I make a concerted effort to be healthy. Doesn't mean I don't eat cupcakes when the whim takes me. But what I don't like is when people assume that I have really good genes because I have a good figure. I work hard for it, because while I may be able to not eat well and not be grossly obese, I easily fill out into decidedly overweight (and all the self-esteem issues that go therewith).

    Long story short (too late), I feel like it's definitely both nature and nurture that make us the size we are...

  7. I'm no scientist, of course, but to me, Nurture definitely tops Nature in that. Nobody will convince me that our genes have oh-so-suddenly changed in a mere 100 years to make us prone to OMG!obesity, when it took hundreds of thousands of years for us to evolve to the point where we are now. It is impossible that our environment (processed & packaged foods, using cars instead of our feet, etc.) does not play an important role, the way it has changed, mainly over the 20th century.

    I agree that some of us have the genetics to gain on weight easily (it's a survival mechanism, after all -- WE are the people who perpetuated the human race, when others were dying of starvation). I have such genes as well. But I still don't blame my fat on my genetics only. Maybe it's 30% genetics and 70% environment, something like this, but certainly not genes only.

    I also wouldn't blame people themselves -- no "lazy fat people" and similar crap -- because, seriously, the world as it is does not exactly help us. I bet everyone of us here has once grabbed a package of food, finally read the labels, and realized that there was HFCS in it. Or when we order what we think is a "healthy meal" at a restaurant, who can say if it's really healthy? (Cf. the "healthy salads" at McDonald's. Ugh. *urge to kill*) And lots of us sit at a desk all day long at the office, instead of working on the farm like our great-grandparents did. Not to mention what other commenters wrote, about parents keeping children inside because they can't supervise them.

    So yeah... I'll never deny that there is a genetic predisposition. However, IMHO, it is just that.

  8. Interesting. I am the oldest of 4 siblings, the youngest 2 being younger by quite a gap. The sister closest to me is 1 1/2 years younger. When we were elementary/grade school age, my sister was chubby and I was average size. She was nowhere near obese mind you, but definitely heavier than I was.

    I was an extremely picky eater with a serious sweet tooth, disliked most veggies. My sister liked fruits and veggies of all kinds. We had very little in the way of junk food around, but my mom usually did have some home-baked goods around like cookies. Not that my sister didn't eat cookies mind you, but she probably didn't love them as much as I did, and she would eat just about any healthy food that my Mom would put in front of us.

    As far as activity level goes, we played together so there wouldn't have been much difference.

    So why was my sister chubby and I not?

    She got braces in her mid-teens, at which point eating anything became a chore. She got skinny and she has stayed that way. She is a full-time mom of 3 and she never stops. Knowing her, she forgets to eat half the time.

    I on the other hand work a desk job. Now I'm the chubby one. This makes sense. But as to why she was a chubby kid and I wasn't, I have no idea.

  9. "Jump Off the Roof with a Grocery Bag Parachute" Please let the record show I never used a parachute.

    I was a skinny kid. If I didn't feel like eating, I didn't. It was nothing to lose 5 lb. over a weekend. I never set out to lose weight, in fact I tried to gain it, but it just happened.
    In my case it's nature and nurture, and I think that's what it is in most cases. Genetics have a role, of course, but I don't think they are necessarily an absolute.

  10. I am with you, Bag Lady - I was quite skinny and had the dreaded "bird legs" and was teased mercilessly..
    Things are sooo different now - we ate much more home cooked meals, fruits and veggies, plus I don't think we stayed still the entire summer between the running, swimming, biking, playing, etc.

  11. Can't comment, suffering from depression brought on by childhood traumas (not really, I wasn't big until I quit being active.)

    But seriously, it wasn't all that long ago when kids grew up in these things called "neighborhoods" and they had "neighbors" to play with. I remember coming home every day after school and running outside to play with the neighbor kids. We would stay out until the street lights came on and we had to go in for dinner. Not to mention the fact that my parents encouraged us to participate in team sports... I probably did every sport at one point in time!

    So yeah, then came high school, and smoking pot, and not careing about much...and the weight gain. It was a clear correlation for me. College was even worse

    Also, both of my parents have always had to watch what they eat and stay active to keep from being over weight.

    So yeah, nature and nurture, they both matter.

  12. When I first saw this study, it made me think of the whole cholesterol thing. The majority of our own "cholesterol" is determined by our genetics. However, our diet, for the vast majority of us, as the factor we have more direct control over, will determine if our levels are too high.
    By the way, Crabby, the column on VO2 max is up today. It was a "labor of love" :-)
    Dr. J

  13. PS: Hey JavaChick!
    Plenty of adults get braces, it's never too late :-)

  14. I love sending my kids out to the backyard to play by themselves. One of the biggest reasons I put up a fence last summer. Can't wait till they can do it again and I know they're looking forward to it to.

    Good conversation today, I have seen the way my family eats change dramatically since I started doing something about my weight. I believe it is a combination of both nature and nurture, but kids aren't buying the food. The apple doesn't fall far from the tree, too bad we're all to lazy to pick them up and eat them.

  15. As I see it, nature is the canvas and nurture the paint.

    As with many genetic tendencies we are at risk. Cancer is one of those things to which it seems we are genetically predisposed. If we have the gene that puts us at risk for lung cancer, the risk is there no matter what. Occasionally we hear of non-smokers and even those not consistently exposed to second-hand smoke developing lung cancer. However, if we have that gene AND smoke, we are increasing that risk greatly.

    It's not so different with obesity and excessive eating. You do what you can to minimize the risks. And you can only control the nurture part of this deal.

  16. Fascinating debate, as always. There's definitely a genetic component at play. I'm five feet tall and curvy, and because of my genetics, I'll always have to eat healthfully and exercise to keep my weight stable. At the same time, though, nurture plays a huge role in weight. Most kids aren't grocery shopping, cooking, planning meals or buying take-out, nor are they directing many of their own activities.

    I'm writing a book right now about mothers, daughters and body image. It's amazing to me what an important and lasting role parents play, both in what they teach their kids about what it means to be healthy and in what they teach them about the role of food in their lives. I've talked to some women who are still dealing with what they were taught as kids, even in their 40s, 50s and 60s.

    I think parents (and I am one) have to remember that nurturing good habits goes beyond just telling kids what they should do. If you want them to eat vegetables, they have to see you eat them, too. Then again, all parents know that children are ultimately little people with minds of their own. All we can do is try to set an example.

  17. I think one only need take a look at the kinds of foods that are marketed to children to understand why so many of them are overweight. We as a society need to get reacquainted with real food and get over this idea that "oh, kids will never eat that, let's just give up and give them dinosaur-shaped 'chicken' nuggets* instead."

    *those things really creep me out. I seriously doubt there is much if any actual meat in them.

    Actually, that reminds me of a theory I heard once: that kids are resistant to vegetables and other strong-tasting foods because the first real food they usually get is cereal, which trains their palate to prefer bland foods.

    Oh, and re: the Jumping Off The Roof With A Grocery Bag Parachute Game: at my elementary school they used to have a wooden fort-type-structure with outside platforms at various heights. We used to jump off of those. I'm actually kind of surprised, in retrospect, that nobody broke any bones... The new "safer" plastic equipment that replaced it wasn't anywhere near as much fun. :p

    And an off-topic question if you don't mind: Crabby, you lift Real Weights. Where should I go to get me some of those, and what's a reasonable price to pay for them? I want to get serious about my strength training.

  18. I think it is dangerous to tell people that they have fat genes and will most likely be fat most of their lives. Just because you have the genes of something doesn't mean it will manifest. More importantly we need to look at lifestyle. When we older Gen Xers were kids we had PE and remember those Presidential fitness tests we had to take. Still to this day I wanna do one pull up because of those tests. We also didn't have half the fast food or even any of the electronic devices that these kids have today. All the internet, TV, and Playstations are giving kids more reasons to sit on their arse all day than go outside and play and just move. Heck, most school have even eliminated PE all together so the kids can spend more time on raising test scores. It's ridiculous. Genes will msot definitely afffect your body shape ie Apple, Pear, but it doesn't doom you to a life of obesity. Studies like this make me mad.

  19. I might sound redundant but yes, they both matter. (out of my three, two are wiry, one is stocky. same activity level, same food, etc.)

    I just really like's dara's comment, I agree the most important thing to do is to try to set an example. You want kids to eat their veggies, you can't be eating like crap...all the time anyway.

  20. I read over the study and it seems interesting, but comparing the MBI and WC of adults and their kids is hardly making a genetic link, twins or not. If the whole family eats badly and doesn't exercise they'll likely be fatter, both of them. It's not genetic it's just logical.
    Plus they stated a few obvious things...like increase WC being associated with higher BMI...and I'm not sure how accurate BMI is for children. I've read conflicting reviews of BMI and how it's not always accurate for measuring obesity. And personality has to be factored in as well, outside of genetics and environment. They're not being force fed. I liked that they compared the whole gender thing...but the fact that the environment was twice as high for predicting the WC and BMI index - well, it made me a little leery to take their conclusions as fact. And honestly - this suffers from "too many stats-itis". I'm a scientist and this was a rough read, but their P values of 0.586 as a highest value...well that is not high enough to be definitive.
    It's interesting, and I think deserves further work, but even the authors talk about personality and the fact that obesity is due to both environmental and genetic factors. Some people are *just* fat just like some people are *just* thin - a friend of mine was large and she was an aerobic instructor who ate like a bird. It's the "most of us" in the middle that make it confusing.

    I too am more worried about parent's who don't know their kids are obese. I was a large kid and it was tiptoed around. My parent's both worked and I ate when bored, and noone told me not to eat bad things. I wish someone would have helped me learn portions sizes and appetites as a child...and a lot of parent's feed their kids like they did when they were kids, or feed them for love and make them finish their plate. We're so much less active now. It's sad that there's a study trying to show why we're fat. It seems straightforward to me...We eat more than we burn off...that's it.

  21. "As I see it, nature is the canvas and nurture the paint."

    Hilary, you never cease to amaze me!

    I think it is a combo for sure. I have a friend that is writing a blog on whole/natural foods and eating styles. It is very interesting stuff. She writes at KellyTheKithcenKop.com

    I think it takes more effort than it used to to eat healthy foods. Everything is so much more processed now and it takes lots more effort to find the good stuff, let alone prepare it!

  22. Some people are predisposed to being overweight due to genes. But note the word predisposed. It does not mean they are guaranteed to be overweight.

    I am predisposed - my whole entire family is overweight, and I'll never be a size 0 even if I stopped eating and worked out constantly. But I'm not overweight. Why? b/c I watch what I eat and I exercise. But am I more likely to be overweight than my friends who come from "skinny" genes? Most definitely.

    There are people out there who can eat whatever they want (the bitches!) and not gain weight and there are those that are the opposite. Genes definitely play a large role.

    However, nuture does too. My genes predisposed me to having weight issues but learning how to binge, how to eat in secret and how to use food to make me feel better from my mother gave me that weight issue.

    So feeding your kids processed crap and fast food and having your house full of pop and chips and candy and then allowing them to sit on their asses playing video games instead of playing sports or other extracurriculur activities or even just playing outside, like you mentioned Crabby, will teach them the bad habits. Combine that with a "fat" gene and those poor kidd just does not have a chance.

    I totally believe that Nature and Nuture combined make the person - I took genetics all through university but my major was in psych (a classic nuture science!) so I was always hounded by both sides of the argument and really the middle is what makes the most sense to me! Anyways, my problem with the nature theories is that it takes accountability off of us. How many times have you heard and used yourself these excuses "I'm big boned" (I used and is BS for me - I have a medium frame) "my metabolism is slow" (used this too but acutally mine is real fast - why I'm hungry all the freaking time) and so on and so on. Just b/c you may be predisposed doesn't mean you can't do anything about it! Take accoutability of your own actions and teach your kids how to live healthily by example and by enforcing good for them rules!!

  23. Thanks everyone! I love hearing your personal stories. And you all sound so dang reasonable about acknowledging both sides and not seeing things as black and white. No "screaming baby heads" in this bunch.

    Dara--I'll be very curious about your book when it comes out; sounds like a great subject.

    And Chickengirl--
    Actually, I only do a couple things with free weights and mostly use the weight machines either at gyms or at home. Although we just had to sell our home gym, unfortunately, because we're moving cross country).

    All I know about free weights is not to get the cheapo kind we bought once with fake silver paint that flakes off and lame fastener thingies that don't hold the weights on very well. (I think they were Weider's or something). And that buying used is sometimes a great bargain.

    As to the home gym machines, we had a MultiSports one for almost fifteen years and it was great. We bought it for about $500 though I think they're more expensive now. But it saved me big bucks in gym memberships for many years.

    Good luck on your strength training, and sorry I'm not much help!

  24. OK, so I'm a fat kid...
    But I don't think you can have one influence without the other...

    I would say that the majority of my weight gain was during 8th grade and my freshman year of high school...However, I was in no way a sedentary(sp?) child...The weight came after I stopped dancing...I still play/ed competative Volleyball, but still put on weight...I was so active in 8 million extracurriculars and other activities that I rarely slept and would always be grabbing the most convenient food options that kept me nourished...

    I don't put any blame on my 'rents for my weight, the minute I started choosing what I wanted to eat, it all fell on my shoulders. It's my fault, but the choices I had didn't help...At school, there was NOTHING healthy, and I include dorm living in this category because I am not convinced that the "healthy" options they gave us were actually healthy. Then moving out on my own, it was easier, and I thought cheaper, to stop and get Dairy Queen or Burgerville on my way home from class instead of going to the grocery store...

    Even today though, it is all about convenience...The boyfriend and I make a concerted effort to cook dinner instead of going out, but more often than not we end up going out because it's easier and we can't think of anything to make...It is just how the world is...Shitty and fat and waaaaaay to convenient...But the effort and the desire to fix it must be made and acnowledged...

  25. All through childhood, I was fat and so was my brother dweeb.

    My brothers Jeep and Kev were thin.

    We all had access to the same food, played baseball in the same league and came from the same uterus.

    We didn't have nintendos or computers until we were teenagers so you can't blame all of the crazy technology that kids have now, eventhough they were around when I was growing up (our parents just couldn't afford them AND four kids).

    Now Jeep, Dweeb and I are health conscious and try and keep in a good weight range while Kev is in an unhealthy one and blames genetics.

    It's not genetics and it's not parents. as I used to say in IT - it's a user problem.

  26. INHO a bit of each, and it's different for each of us. It makes sense either say.

    If it's genetic and your mom or dad have the gene, you could get it....possibly even from both of them. But on the other hand, if it's because the parents don't eat right, are sedentary, etc then the baby probably gets an OD on sugar while it's developing....possibly causing genetic damage, or desensitize the baby to glucose...who knows.

    And, on top of that, mom and dad are possibly going to continue their poor eating habits and feed the kid the same food.

    Nature or nurture? A bit of both.

  27. "we Baby Boomers were often permitted to play outside for hours and hours at a time, completely unsupervised."

    Have you heard Denis Leary's bit on being shot in the head with an arrow? His brother decided to shoot an apple off his head, and hit him in the forhead! It's a riot! And so true! Chemistry sets, wood burning kits, models with real glue, and yes, arrows with real metal tips! We had fun too! LOL

  28. I looked at the design and the study design has several flaws. The real truth is to do this study appropriately, you would have to be highly unethical and split the twins up. Put one with healthy/whole grain/running parents and one with McDonald parents and see over a period of twenty to fifty years. Since no one is going to ever be able to do this, we need to be practical. Genes do have some role, however the ballooning of America in the past 50 years can not be genetic because we still have the same genes. Genetics does not evolve over one or two generations.

  29. Ugh... trying to do an essay on "Nature vs. Nurture: Obesity," and it's not going smoothly.

    As part of the assignment, I have to choose one side, so I chose nurture. Big mistake!
    It's as if everyone on the internet is blaming genetics for their size. (Surprise, surprise.)

    This page helped, but I think I need to search further. Dang.


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