To emphasize, I do not actually believe that assortative mating is the cause of the obesity epidemic.
A major challenge to any theory, however, is that it has to operate as a multiplier. The heritability of obesity is seemingly constant. That is, what we mean when we say “Whatever is happening, its seems to be happening to all of us”
If that were not true then presumably some people would be protected not only by their genes but by their environment. In which case heritability would fall.
For example, suppose that it is fast food. Well some people may be adopted into families which don’t eat fast food. This person should have a large degree of protection that is not genetic. Yet, the data don’t bear that out. Environment has not become more important.
Suppose it was watching TV, or drinking Soda, or any of those things. Then some sort of environmental protection should show up in the data but it doesn’t seem to.
This is why I have argued before that I suspect it is a ubiquitous small molecule. Its something that’s in everything. Maybe a universal preservative. Or, a legally mandated fire retardant. Something like that.
Some of the people I am fans of suggest that it is sweeteners like High Fructose Corn Syrup. This is not nutty as there is a clear mechanism and HFCS is more universal than you might think. However, its still a big hurdle. Surely some parents restrict their kids exposure to HFCS. Why don’t we see that?
Further my point is that a wholly genetic theory of the obesity epidemic can be constructed and to my knowledge no one has laid down solid evidence that it is in fact wrong.
That’s different from thinking its right, but it does highlight the state of our ignorance.
Also, for there are a couple of go-to studies on Obesity and Heredity. I’ll pull a chart from one of my favorite hereditary studies, the Sacerdote’s “What Happens When We Randomly Assign Children to Families” because this is the type of study we are typically tying to emulate statistically.
![image_thumb[3]](http://modeledbehavior.files.wordpress.com/2011/11/image_thumb3.png "image_thumb[3]")
This shows the relationship between the child’s outcome and that of their adoptive parents and their biological parents. The children are on average about 30 or so I think.
Some outcomes are of course going to be influenced by neither. However, you can get a sense of the relative contribution of “role model” vs “genetic” effects by looking at the ratio.
On this measure BMI and Height are about the same. Studies usually find height is about 90% genetic and BMI is between 70% and 90% genetic. Usually measures of obesity as a binary variable find lower genetic effects but because “unexplained” variation is categorized as environmental this is at least partially and possibly entirely due to binary cut-off.
That is, if you have a BMI of 29.9 and your twin has a BMI of 30.1 then you are obese and he is not. However, this would look like unexplained variation when really the variation is an artifact of the cut-off.
Lastly, you can build a model that says its just self-control. One’s self-control is genetic and what has changed is the opportunities for indulgence. Maybe, but its hard to square that with childhood obesity which is under control of the parents and thus we should see a strong affect of strict adoptive parents.
There are also some other issues with self-control being the mechanism that I’ll just mention. One, self-control seems to be rising by almost all other measures yet obesity is rising. Not a killer problem for the theory but perplexing.
More importantly its hard to square with the stability of weight, which is probably the biggest or second biggest next to heritability, stylized fact about obesity. That is, if you always over eat you don’t get fat, you get fatter. Presumably, you will get fatter and fatter over time.
However, non-dieting obese folks have a weight stability that is roughly the same as thin people. Its as if they tried to go exactly to a particular too heavy weight and then stop and act like a thin person with 50 extra lbs.
Why does it stop like that?
That’s a puzzle.
It also *suggests* that there is some regulating mechanism that is set to the wrong parameter. We can also measure regulating hormones and they are systematically off in obese people, but this is enough for one post.
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Monday ~ November 28th, 2011 at 5:57 pm
IVV
I can only speak about myself.
I’m about 5’10″ (175 cm) and weigh about 230 lbs (105 kg). I used to be consistently 250 lbs until I moved to California, then became 235 lbs consistently. Then I moved to New Jersey following my wife for a job, and spent the next 6 months contracting and looking for work. My weight dropped to 215 lbs quickly and stayed there. Last year, now that things have settled down again, the weight quickly moved back to 230 lbs, and has stayed there since.
What was most interesting to me, however, was that about two weeks ago, I had a day off. Instead of a standard day off with my wife, out doing something we planned together, I was home alone, free to do whatever I felt. I spent most of the day sitting around online, doing nothing, but enjoying it to the point that I kind of skipped lunch. The next day I weighed myself, and my weight was 228-229 lbs, instead of 231-232 lbs as it was before. It’s stayed there. Even after Thanksgiving.
I wonder if unstructured time helps with weight management. Not sure I understand the mechanism, but it’s the only thing I can think of that I had in common during the times I lost weight.
Monday ~ November 28th, 2011 at 6:36 pm
Drew
“Studies usually find height is about 90% genetic and BMI is between 70% and 90% genetic.”
Don’t these studies find that weight (or height) is between 70% and 90% (or 90%) *heritable*, not genetic. My understanding is that these are two distinct things and heritable traits are usually affected by the environment. Razib Khan makes this point here: http://blogs.discovermagazine.com/gnxp/2009/07/heritability-of-height-vs-weight/ – he also suggests that the high heritability may be due not to weight related genes but “variation on cognitive traits which result in a propensity toward certain behaviors which result in weight gain.”
Monday ~ November 28th, 2011 at 7:13 pm
Aaron Miller
This is really interesting stuff to me, as I’ve been digging into time discounting as it relates to obesity.
I’m inclined to think that self-control, a.k.a. impulsivity, is the primary culprit, and it mostly squares with your observations. This recent lit review supports the position that impulsivity is heritable.
http://www.sciencedirect.com/science/article/pii/S0272735811001292
Regarding weight-maintenance and obesity, a heavier person needs more calories to sustain current weight. Overeating habits might simply become maintenance habits over time. But these habits still probably spike blood sugar levels and satisfy immediate desires the same way.
Other research links impulsivity and obesity. This paper, for example, demonstrates a positive relationship in children between impulsivity, obesity, and the reduced likelihood of treatment success.
http://www.sciencedirect.com/science/article/pii/S0005796706001173
I also don’t think parents have as much control as you assume. My kids aren’t overweight (in spite of my being a bit overweight), but as a parent I doubt I could control my kids’ eating very well as it relates to overeating. Other than my kids telling me they are hungry, I have very little feedback about the right amount of food for them. If they are impulsive eaters asking for more, I might just think they’re growing–up, not out–and need the calories.
Monday ~ November 28th, 2011 at 7:47 pm
Bruno
What a bunch of BS just to don’t face the fact that you fat americans have the worse diet in the world! Your owner$ want you to eat exactly as you do, that you believe it is an essential part of “american way of life”, fight for it, defend if, PAY for it.
A mysterious, ubiquitous small molecule. Yeah, sure.
I’m italian, our diet is not that good as well. We eat loads of fat, diary products, starches and sugars. But we are not nearly as fats as you are.
Point is… what can make your owner$ more happy? Follow the money. People eating healthy, unprocessed vegetables, maybe cooked at home, o people eating meats, diaries, ultra processed foods? And is not just the value of the food. The bis business is the healthcare. You are so pathologically weak that the average american need constant medical assistance/drugs just to stay alive!
So stop wasting time searching for the mysterious molecule that will allow you to eat junk food all the time, and start eating well!
The simple true is that meats, sugars, fats, refines starches, diaries and industrial foods are just too empty of nutrients, and too full of calories.
Process food as little as possible. Stuff yourself with salads, non starchy vegetables, fruit, pulses and whole grains (and YES, you can over eat on that stuff!). Ban oil (-90%), use walnuts (whole nuts) as you main source of fats. Eat fatty, processed foods (what you normally eat now) as exception, 2/3 times per week, with your friends.
You will give lots of powerful nutrients to your body, like fibers, vitamins, phitochemicals compounds, antyoxidants, and all the protein you need.
Even better, read about Dr. Joel Fuhrman.
This is free advise, at least from now on you can’t pretend that you didn’t know.
Monday ~ November 28th, 2011 at 7:51 pm
IVV
There, there, feel better now?
Monday ~ November 28th, 2011 at 8:55 pm
matt
We are genetically predisposed to eat when food is present and store that food for times of famine. We are not far removed from hunting and gathering in genetic terms. When food is there for the taking we are wired to eat it. It is a losing battle. The marketing and food science fields have taken advantage of this genetic “weakness.” Be happy, drink coke! You are sad, eat chocolate! Be a man, eat a burger! Want a vegetable? Eat a pizza! (sorry, couldn’t help myself).
Its genetics enabled by cheap and available food, weaponized by the agg, food science, and marketing industries/lobbyists. I haven’t done the research but I would suspect that weight has increased with access to advertisements. More TV’s, technologies, and sophisticated marking techniques are a likely culprit. I wonder if countries that regulate advertising have a more stable waistline over the past 20 years?
Monday ~ November 28th, 2011 at 10:17 pm
lfvoss
My weight is directly proportional to the number of baked goods my coworkers bring in.
Monday ~ November 28th, 2011 at 10:24 pm
Chris Stucchio
Weight stability is no longer a puzzle. The Harris-Benedict equation (used for calorie counting) combined with simple calculus shows why people become overweight and then stop. I doubt I’m the first person to observe this, but doing calculus was easier than doing research.
The short answer is that they simply add a constant amount of excess calories to their diet. If a thin person adds 500 extra calories to his diet, he will become fat and then stop gaining weight.
http://crazybear.posterous.com/the-calories-incalories-out-model-explains-we
Monday ~ November 28th, 2011 at 11:20 pm
Lord
That begs the question of why they would add a fixed number of extra calories, or why they wouldn’t subtract a fixed number of calories instead.
Tuesday ~ November 29th, 2011 at 12:46 am
Eden
Read up on Paleo (diet) and try it as an experiment. I think you’ll be surprised by what you find. From an evolutionary perspective, it seems clear that carbs were once a very minor part of our diet. As such, it isn’t a stretch to imagine that we are well tuned to store them as fat when they are available and maintain a healthy weight when calories are primarily available from protein and fats. I think this will be mainstream thinking within 10-20 years as the data continues to accumulate to support this position.
Calorie control (or involuntary lack of calories) and exercise can play a role in maintaining weight, but when calories are abundant and a significant proportion are from carbs, weight gain seems almost unavoidable.
Tuesday ~ November 29th, 2011 at 7:34 am
Bruno
Except that we are DESIGNED to work on carbs! Our brain use carbs, don’t it? 20% of our glucose is needed just to think clearly.
Try to run, think, have sex and even sleep on ketones!
I’m sorry Atkins-adepts, as tasty bacon, fried eggs and steaks can be, they are not the answer, and Science will never be on your side.
Besides, our body seems to hate to transform carbos into body fat, since the process require many hours, and 25% on it’s energy got lost in the process.
Fat can be PERMANENTLY STORED in our body within minutes, and only 3% on it’s energy content is lost on the process.
What about fewer fats (the healthy ones), and more WHOLE GRAIN carbos?
I know it’s hard to believe, after a life time of wrong, misinterpreted, data, but since you probably already try everything else, why not this one?
Give it one week of real commitment and you will see what’s really “unavoidable”: loosing weight.
Unless you read scientific blogs about food just to justify your bad eating habits, trying to find the bad molecule that makes you so fat…
IT’S NOT GENETICS! IT’S NOT SOME MYSTERIOUS CHEMICAL!
IT’S BAD FOOD!
Tuesday ~ November 29th, 2011 at 12:19 pm
Eden
Bruno – Please read some of the modern research data and evidence behind Paleo before you rail about low carb diets. Many of the statements and claims you made are fundamentally incorrect. I run, lift weights, sleep, and use my carbohydrate fueled brain effectively throughout the day without consuming more than about 60 grams of carbohydrates on most days. Also, the Atkins approach has significant flaws and is not the same thing as Paleo.
As far as me trying a whole grain based diet, I was raised eating a whole grain, vegetarian diet, and continued to do so through my twenties and it nearly killed me. By my late twenties I had health problems you would only expect to see in 70 year old men. Switching to Paleo resolved the underlying problems…and I lost weight despite eating as much as I wanted of high fat and protein foods. I think more clearly, and don’t get food cravings, energy spikes, crashes, or mood swings, all things that were common for me on a higher carb lifestyle. I personally know several other people with identical stories and the online Paleo community has thousands of more examples.
Paleo (unlike Atkins and many other diets) is about eating real, whole foods that we evolved to eat over millions of years. And modern nutrition research is gradually catching up to the obvious fact that whole grains and carbohydrates in general were not available to the human species until modern agriculture took hold in our recent past. Just because we can survive on processed and high carbohydrate foods does not mean we will thrive on it.
I challenge anyone to try a strict Paleo diet for 30 days and come back here to share their results. There is more than enough free information online to give Paleo an honest try or you can buy a single book from any number of well respected authors and follow that.
Tuesday ~ November 29th, 2011 at 6:23 pm
Matthew C.
It is bad food. It’s just that you have misidentified the bad food. The true culprit is fructose (by far the worst) and processed grains (also promotes obesity).
I have lost 50 pounds and my son teenage son 60, down to a normal range for both of us which has been maintained for more than six months (in his case very trim indeed, since he didn’t abuse his body for 40 years with bad food). What do we eat? As much meat, eggs, cheese, olives, nuts, etc. as we want to. What do we avoid? Sugar, soda, refined flour, and the like.
The people demonizing fat and promoting carb consumption have sold America a bill of goods that has made us fat and sick as hell. It’s time for the truth to be told and understood.
Tuesday ~ November 29th, 2011 at 11:05 am
Corey Mutter
A fatty’s perspective: (5’10″ 305lb)
The “put the fork down” contingent misses the point (I know you don’t, Karl). I have a reasonable amount of general willpower, I can hold down jobs, stay monogamous, maintain good finances, etc. But eating reasonably requires, for me, about the same amount of willpower that it would take for a fraternity to quit drinking. Or what it would take to remain celibate in a world where there was a cheap, legal brothel on every corner, and threesomes with movie stars were $20.
From my end it feels like an addiction, and I don’t have the luxury of quitting cold turkey, so to speak.
I can lose weight by counting calories, and am in fact doing so now. But the only way I’ll be able to keep it off is by pre-committing to start counting calories again whenever my weight drifts upwards.
Tuesday ~ November 29th, 2011 at 6:18 pm
Matthew C.
I struggled with weight and exercise for years until in January of this year I decided to eliminate sugar (for a period of time) and eat very little carbs. After less than a month I had lost almost 20 pounds, eating whenever I wanted to. By six months I had dropped 50 pounds, and have kept it off since then. My teenage son was also overweight and has gone on a similar dietary change and lost even more than me.
I can only recommend in the strongest terms that everyone who struggles with overweight issues try out a similar dietary change for a few weeks and see how that goes.
Tuesday ~ November 29th, 2011 at 12:31 pm
Bruno
An addiction, indeed…
Since many foods contains exorphine, food CAN be addictive as cocaine or nicotine. And high glicemic load foods will make you feel super hungry once your blood sugars hit the ground.
Obviously McDonald & Co. know very well how to make food even more addictive!
So, as it take some effort to quit smoking, it takes, at first, some effort to stop eating addictive foods.
Since the generational chain of (better than now) food habits knowledge has been broken, it’s upon us now to re-learn it. The reward will worth it, anyway.
One thing I can tell you: once you can establish better, healthy food habits, junk food will taste worse than you thing, and healthy, unprocessed food better than you remember. And you will still be able to broken the rules from time to time. According to your town with free brothel analogy, it will be like you can still have plenty of sex but with simple, natural beauties, not empty, over make-up hookers
P.S. You don’t need to count calories if you eat the right kind of food! All you can eat, everyday!
Tuesday ~ November 29th, 2011 at 6:11 pm
Matthew C.
“P.S. You don’t need to count calories if you eat the right kind of food! All you can eat, everyday!” — absolutely correct. Counting calories is what people do when they are starving themselves while eating the kinds of food that promote hormones that keep your body from burning fat. If someone is hungry all the time, they are eating a toxic diet.
Tuesday ~ November 29th, 2011 at 1:00 pm
from Italy
I do not know well this topic but it seems to me that comparison with other countries would be of help. If it is some kind of molecule, its pattern of diffusion would be the same of the pattern of diffusion of the epidemic, so if you study how the epidemic grew in the US and in Europe this maybe can give some clue, also because in Europe it hasn’t exploded as in the US yet.
PS (almost OT)
maybe the strategy of the EU leaders in managing the current crisis is to avoid a full obesity epidemic in Europe… by starving its people.
Tuesday ~ November 29th, 2011 at 6:08 pm
Matthew C.
It IS in fact, a small, ubiquitous molecule. Fructose, in fact, via sucrose (~50% by weight) and HFCS (55+%).
Our fructose consumption has gone up more than 100% in the past 30 years, and more than 300% since 1900.
Glucose can be burned anywhere in the body, while fructose must be processed in the liver (like alcohol!). Excess fructose consumption leads directly to fatty liver, insulin resistance, metabolic syndrome and obesity in those of us adapted to storing significant amounts of fat in response to high fructose load (ONLY found in the summer / fall in the evolutionary environment). But even in thin folks, excess fructose consumption is dangerous causing cholesterol and lipid profile problems.
The low carb folks are correct though that the best way to treat obesity is to drastically reduce carbohydrate intake. That will clean the fat off the liver and reverse insulin resistance faster than any other approach.
At 41, I was able to lose 50 pounds and keep it off just by adopting a low strict low carb / no sugar regimen. 17 pounds of it in the first month. I eat as much as I want, and eat more carbs now than when I began this new way of eating (but avoid grain products mostly) and the weight has stayed off. Sugar, day in, day out, is a killer.
BTW my son adapted a similar dietary change and lost even more weight and is now very fit and trim. Simply by avoiding eating processed grains and sugar.
The obesity epidemic is not a mystery. It is caused by eating the wrong kinds of foods in the wrong quantities.
Wednesday ~ November 30th, 2011 at 1:31 am
Bruno
I’m happy to hear so many success stories here.
Personal stories doesn’t really matter if we want a scientific, rational approach.
I’m not a fanatic of carbos, neither of any particular diet.
Atkins diet DO work for promoting weight loss. That’s make it a good diet? If you follow it over long periods of time, you will surely die over premature death (like mr. Atkins itself). That’s why you are forced to eat plenty of vitamins and other nutritional (in pills) during the diet.
Paleo I don’t know, but I think it will be better than Atkins.
Fresh, unpreserved meat is not evil, but the saturated fat’s within are.
I believe in a common sense approach to nutrition. Each person have different age, DNA, level of activity, and so on.
So, the latest field in nutrition are the amazing properties of phitochemicals. It’s a class of organic compounds, mostly yet to discover, which are extremely powerful. There’s plenty of them in unprocessed vegetables, whole grains, fruit, pulses, while practically none of them in alcohol, oil, meats, processed and overcooked foods (thus the name empty calories). Think about lycopene, flavonoilds, antioxidants, etc… Think about the fact that there’s more than 10.000 phitochemicals in a humble tomato.
The “ugly true” that’s emerging is that our body was design to get load of this compounds from the diet (this limit the complexity of DNA), not by producing them by himself. He NEED them to prevent cancer, stroke, body inflammation, hypertension, and so on. Vitamic C (produced in the liver by almost any mammalian, but not by humans) is just an example. So, eat meat, if you want. Get 30 or 40% of your calories intake from semi-empty foods (all fats are empty). If the rest of your diet is based on unprocessed produce/fruit/pulse/whole grains, you can still enjoy pretty decent health.
But the best thing to do is to drastically reduce you consumption of empty calories (10~15% top): you will enjoy a happy, long life, and you will be full of energy and concentration trough the day. You skin will look bright and healthy, your body trim and strong.
Get the best health you can trough excellence in nutrition, it’s the most rewarding single thing you can do to improve your quality of live and optimize you chances of success in… whatever you want to succeed at.
Thursday ~ December 1st, 2011 at 4:31 am
Steve Sailer
It’s clearly a class marker that has shifted over time. The fat cats used to be fat, but we haven’t had a truly fat President since Taft. In the middle of the 20th Century, weight and class weren’t closely correlated. Now, they are again.