Monday, June 29, 2009

Did following the experts' diet advice make us any healthier?

To kick things off at my new blog devoted only to health, food, and nutrition, I'm going to show how what we've been eating has dramatically changed in the past 100 years. Most nutrition experts tell us to cut back on red meat and dairy -- and to eat white meat or fish if we must -- while increasing our intake of grains and fruits and vegetables. Since we know that obesity, type II diabetes, and the other symptoms that make up Metabolic Syndrome have been shooting up since roughly the 1970s, we can see whether our changing diet has anything to do with it.

Did we follow the experts' advice? And if so, did it do us any good? Let's see.

The data come from the USDA (see here for the spreadsheets), and they measure the availability of various food types for each year. This isn't the same thing as consumption, but because availability (supply) reflects the demand for it (consumption), when availability goes up or down, we're safe to conclude that consumption is doing so too. The data are all per capita, so we've already accounted for America's changing population size.

We'll start with the demonized foods: red meat (saturated fat! -- actually, most of it is monounsaturated), dairy (more saturated fat! -- which explains why the cheese-eating French have such awful health), and eggs (cholesterol! -- you know, that stuff that gets turned into your pesky sex hormones and vitamin D).




We've been throwing red meat overboard since about 1970. Dairy has been way down since 1940, although there's a moderate rise starting in 1980 (my guess is that it's mostly cheese for pizza). And eggs have plummeted since 1950.

But even the fruits and nuts people will admit that we need some protein -- we should just get it from white meat (chicken breasts with 0 g of fat) or fish (which, unless you eat sardines or salmon, probably won't have any fat either). Have we been choosing these more supposedly healthy forms of protein? You bet. Here are the graphs for poultry and fish:



Poultry has been skyrocketing exponentially since 1940, and fish too has been increasing since 1960.

And what about those cure-all fruits and vegetables? Eat mostly fruits and vegetables, we're told, and you'll be as robust and affable as any PETA member. Unfortunately these data only go back to 1970 instead of 1910, but the trend is still clear -- we've been scarfing down more spinach and blueberries (hopefully not together) than ever before. I've also included graphs for specific foods like the starchy potato vs. the more nutritious dark, leafy green vegetables.





And of course, any healthy diet requires grains -- after all, they form the solid foundation of the Food Pyramid. It's just plain common sense that you can't thrive unless you crunch your way through a sack full of Grape Nuts every morning, isn't it? Here's the graph for grains:


Starting at least in 1910 (and perhaps earlier), we started putting grains to better use -- as bird feed -- but since 1970, we've been steadily reversing that practice. Now when we eat out, it's bread, breadsticks, pasta, rice, noodles, and more bread.

Finally, the one food that everyone agrees is bad for your health -- caloric sweeteners like sugar:


From the mid-1960s through the mid-1990s, we found it necessary to dump more and more sugar on our food -- probably because we'd switched to a tasteless diet of spinach and Special K. Still, for the past 15 years, we've been letting it go (likely as a result of switching to non-caloric sweeteners like Equal). So, we'd misbehaved for awhile, but we've been good -- honest! -- more recently.

To sum up, we've done everything the nutrition experts have told us to do -- and have so for decades. Aside from eating less sugar, all of these supposedly health-promoting changes began no later than 1970, with some beginning as far back as 1940. Surely that's enough time for the benefits to show up in national health statistics, right? Well, let's see what the end results of this gigantic national experiment are.

The experts began telling us what to eat in order to lower rates of heart disease, although once obesity and related metabolic problems became huge, they extended their guidelines to help us get thinner too. Here is a graph showing the incidence of heart disease during the period when all of these dietary changes had begun (from this AHA pdf):


Huh, that's odd -- our hearts seem to stubbornly resist the supposedly heart-healthy food we've been eating. These are total numbers, not per capita rates. Still, the number of people suffering from heart disease doubled from 1970 to 2000, even though the US population was only 1.4 times as big in 2000 (at 282 million) as in 1970 (at 205 million). Therefore, there was a real increase in heart disease rates that cannot be explained simply by a larger population.

Why do we need to look at "hospital discharges with CVD as first listed diagnosis" rather than deaths due to heart disease? Because we could be getting better at saving lives when a person already has heart disease -- in that case, the death statistics will make those sufferers of heart disease invisible. Checking into a hospital due to heart disease sheds better light on the group of people with CVD.

And as if you needed me to tell you what the obesity rates have been like recently, here's a graph showing the prevalence of obesity and overweight:


That's odd -- the lines are pretty flat before the mid-1970s, at least back to 1960 (and possibly before), and they only shoot up sometime in the mid-'70s. Looks like loading up on Total ceral, non-fat salad dressing, and potatoes hasn't done us much good in trimming our waistlines.

So, even though we've been scrupulously following the experts' advice about what to eat -- and those graphs above prove that -- we're more likely to suffer from heart disease, obesity, and other symptoms of Metabolic Syndrome. Does that mean that these so-called experts don't have the foggiest idea what they're talking about? Yes -- that's exactly what it means.

I doubt that eating more spinach has harmed us, obviously. The main culprits are eating more carbohydrates (potatoes, grains, and sweeteners) and eating less of the fatty animals products (red meat, dairy, and eggs). I won't go through the reasons why since, if you're reading a blog called Low Carb Art and Science, I assume you already know why.

But for those of you who, like most of us, weren't aware of how bogus the experts' advice was, here are three links that provide plenty of information in an easily understandable form:

Gary Taubes' lecture at Berkeley
, where he reviews the material in his encyclopedic book Good Calories, Bad Calories.

Tom Naughton's Fat Head blog, where you can buy the DVD of Fat Head, his hilarious spoof of Supersize Me, which lays out how different types of food promote or discourage obesity, depression, and so on. The movie is currently #1 in Amazon's comedy documentary section. (Imagine that -- a documentary that isn't maudlin or obnoxiously political.)

Michael Eades' blog, where the co-author of excellent Protein Power regularly explains the science behind many health and nutrition concerns that we have, especially when new studies come out.

25 comments:

  1. Fantastic post - Great explainations and thinking. Congrats on your new blog! I'm looking forward to what you have for us next!

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  2. I doubt that eating more spinach has harmed us, obviously. The main culprits are eating more carbohydrates (potatoes, grains, and sweeteners)

    A suggestion: a stumbling block for me when I was discovering all this was that "carbohydrates" were blamed for obesity and health problems. They are of course, but as you say spinach isn't. My personal preference is to refer to "high carbohydrate diets" or to keep it short perhaps "starch", to make it clear that one isn't blaming green vegetables for obesity - because the latter clearly makes no sense.

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  3. I wonder whether trends in other predisposing behaviours like alcohol consumption, smoking and physical activity levels also mirror the outcomes data, particularly re. the mid-70s spike.

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  4. Does that mean that these so-called experts don't have the foggiest idea what they're talking about? Yes -- that's exactly what it means.

    The main culprits are eating more carbohydrates (potatoes, grains, and sweeteners) and eating less of the fatty animals products (red meat, dairy, and eggs).


    Brilliant logic, Sherlock.

    Ever consider that maybe, just maybe, its the total caloric intake, no matter in what form, that is making people fat with the associated health risks?

    And that maybe endless battling over what a "proper diet" is, is a waste of time, and just confuses people?

    People are fat because they consume too many calroies. EOT.

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  5. Therefore, there was a real increase in heart disease rates that cannot be explained simply by a larger population.

    Is a death considered the same as a discharge? The reason I ask is that IIRC, it used to be very common for the first heart attack - which might not be preceded by any CVD diagnosis - to kill someone right then and there. No hospital stay.

    Also, what are the definitions of "obese" and "overweight" used in your graph? As you probably already know, the BMI-based definition changed in 1990-something, and BMI itself was not popularly used before the 80s, so the graph may or may not be using the same measure throughout its timespan.

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  6. I'll assume you've seen this?

    http://www.nytimes.com/2002/07/07/magazine/what-if-it-s-all-been-a-big-fat-lie.html?pagewanted=print

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  7. Interesting on obesity rates. I wonder how much rates within ethnic groups have changed.

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  8. You're right here (just like you are re: teens).

    I've been eating clean for years (no junk) with plenty of good fats (coconut oil, butter from grassfed cows, no refined vegetable oil) and lots of protein but decided a month ago to cut out the whole wheat bread/rice/pasta/potatoes and replace them with organic vegetables (min. 1 pd/day).

    Result: lost five pounds in a month. Feeling of continual well-being. Higher energy.

    Starting hill sprints and will probably lose even more fat.

    You'll want to check out these science/research low-carb sites:

    http://wholehealthsource.blogspot.com/
    http://donmatesz.blogspot.com/

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  9. The plot of "Hospital discharges with cardiovascular disease...": what is the effect of the ageing population? (If, that is, the American population was ageing.)

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  10. Unfortunately this drawerful of graphs doesn't make much of a case for anything - I mean, it's consistent with your argument, but there are so many rising and falling slopes that it's also consistent with vegetable consumption (alone) causing heart disease (paging Owsley...), or many other hypotheses.

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  11. simple chart showing the percentage of 4 year olds who are obese by racial group.

    http://researchnews.osu.edu/archive/kidobesprevpix.htm

    obese defined at or above 95%tile of weight for height on a growth chart.

    Maybe parents constantly telling kids to eat more. It is a time honored tradition. These rates are pretty scary. Imagine the health care costs for all those little fatties. Imagine the profits for diet product companies.

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  12. I mean, it's consistent with your argument, but there are so many rising and falling slopes that it's also consistent with vegetable consumption (alone) causing heart disease (paging Owsley...), or many other hypotheses.

    Well it does establish two things:

    1) For at least the past 30 - 40 years, we've changed our diet according to what experts have told us will make us healthier.

    2) Judging by heart disease and obesity, we haven't gotten healthier over that time -- probably worse.

    So it's a test of the claim "If you eat X, you'll enjoy benefit Y." We ate X, but got the opposite of Y!

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  13. Will you post a basic diet plan that you are following?

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  14. Brilliant logic, Sherlock.

    Ever consider that maybe, just maybe, its the total caloric intake, no matter in what form, that is making people fat with the associated health risks?

    And that maybe endless battling over what a "proper diet" is, is a waste of time, and just confuses people?

    People are fat because they consume too many calroies. EOT.


    I'm always amazed at the sheer number of folks that cling to this fallacious logic whenever they encounter the truth about dietary facts versus the conventional wisdom.

    Even when you provide links to articles and books to the likes of Gary Taubes, people still cling to the modern lies regarding healthy diet, calories and exercise.

    Great idea agnostic, for this blog. I've been following you for awhile, and have written a few related postings on my own blog regarding the same topics you have with regards to modern day diets.

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  15. i have subscribed =)

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  16. I am obese, but I can tell you that it's not red meat that makes me so. I can't eat it since I had bariatric surgery.

    For some the surgical way to reduce calorie intake results in vitamin deficiencies so severe they nearly die. For others, the inability to eat meat results in an overdose of soft carbs, thus the weight is regained.

    I was healthy before I had the surgery, and I am decidedly not healthy now. My problems are mild compared to some bariatric surgery patients, but still worrisome.

    Beyond the surgical "corrections" that are likely after bariatric surgery, there is the fact that 100 calories of protein is decidedly not equal to 100 calories of carbohydrates. The body metabolizes them differently. They burn at different rates.

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  17. I'm always amazed at the sheer number of folks that cling to this fallacious logic whenever they encounter the truth about dietary facts versus the conventional wisdom.

    what a brave scientific rebel you are *yawn*

    The majority of the world's population throughout human history has subsisted on calories from grains and starches. Grain/starch production is the very backbone of civilization. There is no other way to produce enough surplus food for cities (and modern meat production is just converting vast surplus grain into meat). The majority of the world's population throughout human history has not had a issue with obesity. Eventually, a lot wealthy late-industrial civlizations started getting fat. Note that these late-industrial citizens, even following a modern "healthy" diet, still eat scads more red meat, eggs and dairy than the typical poor peasant.

    But of course, its the fault of those evil grain-pushers!

    People are fat because they eat too many calories. They eat too many calories because of late-industrial cultural decadence.

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  18. Excellent work, looking forward to more. Second the recommendation for wholehealthsource. Stephan is amazing.

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  19. "People are fat because they eat too many calories. They eat too many calories because of late-industrial cultural decadence."

    Go listen to Taubes' lecture. He talks about a population in Mexico where the mothers are fat and their babies are emaciated.

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  20. These graphs don't seem to me to prove anything, because the data is not specific enough. Your analysis assumes that the changes and trends in these graphs represent average changes in everyone's diets (IE when consumption of a particular kind of food increased or decreased, everyone on average is eating more or less of that kind of food), whereas I suspect that changes in diet vary drastically between different socio-economic groups..

    I think a more plausible explanation, based on my experience, is that high-IQ people with high future time orientation have heeded experts' advice, and are eating healthier (using the conventional definition of "healthier": low saturated fat, high fruit and vegetable and whole grains). This accounts for the trends you noticed re: increased fruit and veg consumption and decreased red meet consumption.

    On the other hand, the low IQ people, with poor future time orientation don't care about the health effects of their diets. As food has become cheaper over the last half-century, and as income has risen, they can afford to eat more and more unhealthy food (steak every other day, lots of fast food, etc.). Because they lack good mental capacity to plan for the future, they eat whatever is tasty, without regard to the health consequences. Their increased consumption of such food has led to the increased incidence of heart disease, etc, even though on average, people in the United States as a whole have been eating more whole grain, fruit and veg diets. Thus you have one socio-economic group consuming more fruit and veg and less meat, and their behavior is obscuring the trends within the group, which is eating more meat and less fruit and veg.

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  21. High-IQ people cannot be driving the trends since, by definition, they're a small minority.

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  22. Here's my take on it, from my 'blog:
    http://www.sciencemadecool.com/2009/07/eat-healthier-die-younger.html

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  23. Agnostic

    Isn't the point that following the advice once lots of other people are already following the advice changes the efficacy of the advice. The trick with shares is to buy before everyone else does and sell before everyone else does. Maybe something similar applies with food. Why? Because high demand inevitably leads to more intensive farming methods, and these will change the character of the meat.

    I remember when we were being told to eat less red meat and more salmon. At the time, salmon was relatively lean. But the need to provide massive amounts of salmon led to intensive salmon farms. The salmon were kept in a confined space, therefore couldn't move as much, therefore became "couch potatoes". Being in such closer proximity they needed more antibiotics to suppress illnesses.

    Has anyone compared the nutritional content of, say, wild Alaskan salmon, with factory farmed salmon? What are the results?

    If I'm right, the best meat to eat will be Moose, Elk and other relatively rare foods.

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  24. To "Anonymous":


    Your assumptionson obesity need some fact checking:

    For many , if not most, obese people, regions of adipose cells do not respond correctly to the imput of restricted calories and exercise that work for a healthy person. These cells are disregulated. We can try to re-establish regulation , but we're still discovering causes. We need to finish doing that , and we need better therapies which take them into account.


    Obesity is a disease involving the disregulation of adipose (fat) cells. Researchers have found many, many causes that have nothing to do with morality. Effects are localized, rather than general; for an exterme example look up lipodystrophy. Disregulated adipose cells will hoard lipid molecules tenaciously. In many cases starvation will shrivel muscle, organ and connective tissues, without inducing adipose cells to give up their hoard.

    Adipose cell disregulation is a hypothesis for which there is scientific evidence - much more evidence than exists for the moral/behavioural explanation, a hypothesis whose prediction power is very poor and for which contradictory evidence abounds.

    There are many examples of non - behavioural factors which have been found to affect lpipid cycling in fat cells I'll invite you to Google "Gary Taubes" . Near the top of the list of links, you'll find a video which explains many of the ways the caloric/behavioural hypothesis fails. It's just too simplistic and explains too little. Taubes, by the way, is a science writer for the peer reviewed science journal "Science".


    Pay particular attention to the photos of the victims of lipodystrophy which Taubes shows. Fat accumulates differentially in all obese persons ; cells in some regions more than others. In lipodystrophy the tendency is pronounced.


    Looking at these photos it's impossible to escape the conclusion that differential accumulation of fat cannot be explained by total caloric intake .


    In fact, he's ignoring some of the data presented in his own lecture. You saw the slides he showed pf persons who extremely odd distributions of fat. But it's not possible that the insulin level in blood in one part of the body can be markedly different from blood insulin levels elsewhere. Blood simply doesn't work that way Some of the cells in the body are clearly more lipophillic than others. What makes one fat cell more lipophilic than another in the same person? It isn't insulin. Something else is going on, and that something else isn't explained in his insulin transport hypothesis.


    In other words, the proof he offers that the caloric model is untrue is equally proof that his insulin model is untrue. Or, rather, not the whole truth.


    A "true" model of obesity in humans is going to be much more complex.(Occams razor doesn't preclude complex hypothese; it merely requires acceptance of the hypothesis which best fits the facts, and in the rpesence of two or more which do , the simplest explanation is "preferred".)

    None of this is to detract from the value of the journalistic effort Taubes has put forth.He has provided a solid basis for disproving the conventional caloric model of obesity . But the need for a replacement model has not been satisfied, by either Mr. Taubes nor by the scientific community at large . Nor myself, of course.




    We do not yet understand the mechanism by which adipose cells are controlled in the body. But we do know factors that appear to disregulate them, and are discovering more each year. Those are the factors that cause obesity.

    Obesity is not a simple problem to solve. Unraveling that myestery is going to take somebody very rich, I think.




    Regards,

    Razwell

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