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Criticism > Monday, 4 July 2011 11:05:32 EST

Lifestyle And Other Weighty Issues

Keywords: health

It seems to me that the more our health and longevity improve, the more people become worried about their health and longevity.  And the real ironic part about it is that many people feel that we're somehow unhealthier than ever before.

I've commented on these kinds of issues before (see here and here).  It used to be my main pet issue that I would argue on forums.  But I got tired of having the same argument over and over again and I decided when I created this blog that I wouldn't focus on the issue.  But once in a while the issue comes bubbling up inside of me and it's good to have this blog to put it all out there.

And upfront I should probably acknowledge that I may be a crank on this one.  I feel that a lot of the panic and hyperbole over lifestyle is misplaced and may be doing more harm than good.  I get a lot of resistance to that, and I think that the medical community in general believes that it's important to beat this drum and do everything we can to convince people to shape up.  I think the medical research community would probably acknowledge that my facts are correct, but still argue that we need to do all we can to convince people to be more healthy.

So as you see, I'm not a medical professional and I have an opinion that differs somewhat from the opinion of most people in the field.  I've always said that expertise is important, and the fact that I disagree with the experts sends up warning flags, even to myself, that I may be completely off my rocker here.  But I think the difference here is one of interpretation of the data, and not of the data itself.  It's the people who outright dispute the facts that you really have to watch out for.  ;)

In any case, I'm not afraid of being wrong, and if I am wrong then I welcome anybody who can show me where I've reasoned poorly or mistaken my facts.  I still think I'm right on this one, though I want to assure everybody up front that I don't believe there's any kind of conspiracy going on.  I think there are some serious biases that aren't being acknowledged enough, but I don't think it's anything nefarious.

I'm not completely alone in my thinking on this though.  I've transcribed a quote from a speech given by Dr. Ben Goldacre, author of the popular book "Bad Science".  I know I've used this quote before but I think it covers my position on this really well:

Research into nutrition and health has come in leaps and bounds. There's been a huge amount of material, and there's a huge amount of material to play with, and there's a huge amount of material to obfuscate around in interesting and new ways.

And more than that, there's also an interesting historical, political, and social context.... Tobacco: Public health epidemiologists enormously buoyed by this extraordinary discovery that tobacco causes 95 to 98 percent of lung cancers. ... At the same time, the patterns of disease were changing, because, of course, golden age(of medicine), better treatments, and also improved public health in terms of clean water and so on.

People were living longer and people were dying of diseases of old age which sort of felt like they must be lifestyle diseases. And mainstream medicine made promises that it couldn't deliver on. Richard Dole writes in the introduction to a very famous tract on epidemiology in the early eighties confidently asserting that either a third or two thirds of all cancers will turn out to have dietary or other lifestyle causes.

We haven't been able to pay out on these promises. That's not what the evidence has ultimately shown. We've found shavings of changes in risk, usually in observational studies. Whenever we've tried intervention studies on diet... If you look at the evidence in total, actually, it turns out that we weren't really able to pay out on the very specific promises that we were making thirty years ago.

...The only real genuine evidence, best thing you can say for most of the population (in terms of nutrition and health) is "eat lots of fresh fruit and veg."

That last part is important too, because when I have this argument with people I'm often accused of saying that people should be able to eat whatever they like without consequences, like I'm encouraging gluttony or something.  So I want to make it clear that I think eating your fruits and vegetables and being active are very good ideas, and I encourage everybody to do more of that.

But I'm very concerned when it seems to me like we're trying to convince people to change their ways through misleading fear tactics.  For example, how often do we hear that the obesity rate in the US is continuing to increase?  Well, the claim is wrong, but it's wrong for a very interesting reason.

Overweight and obesity rates did rise during the 80's and 90's, but they seem to have stabilized somewhere around 1999 for both children and adults.  This is according to data from the NHANES study, which is the major source used by the CDC and other health agencies for their prevalence statistics.  The rates for both obesity and overweight have been holding steady in the 30's, 32% for obese and 34% for overweight.

The importance of the NHANES is that it's a cohort study, which tracks a stable population over a number of years and actually takes physical measurements for it's data.  This is the go-to database for information about the measurements of prevalence in the population.

Now I think it's fair enough for medical researchers to come out and say that this rate is higher than they'd like it to be, and they did beat that drum a little bit.  I've seen several quotes where we're warned not to become too complacent just because the rates have leveled off.  But at the end of the day that message just doesn't sell as well as the alarmism that we're continuing to balloon out of control.

Enter the Behavioral Risk Factor Surveillance System (BRFSS).  The BRFSS is a telephone survey which helps provide some extra perspective on health issues.  It's good to have an extra data point like this, but it's important to keep in mind that these are self reported measurements over the phone.

So during the same period when NHANES tells us that the obesity rate has been stable at about 32%, the  BRFSS tells us that Obesity has steadily risen from about 20% and is now at about 27%.

It seems fairly obvious what's going on here.  The obesity rate has been under reported by the telephone survey, and increased public awareness has convinced more obese people to become more candid about their measurements over the phone.  It's only the self reporting of obesity that has risen, not the actual rate.  Obesity is still under reported, so the BRFSS still has room for the rate to continue rising.

And the idea that we're continuing to get fatter makes better headlines than the fact that the rates have been stable for over a decade, even if that stable rate is higher than the one reported by the BRFSS.  And so we continue to see headlines about how Americans are continuing to balloon in weight out of control, supported by quotes from the researchers who are looking to promote their research.

The same is true of the prevalence of diabetes, which has been stable for even longer than the rate of obesity but continues to be reported as rising by the BRFSS.  What we're left with is a sense that things are getting worse when the full story indicates that that's not the case.

You may ask at this point "What's the big deal?  So they're being a little sensationalistic, they might convince people to lead a healthier lifestyle that way and really make a difference!".

Well, first of all, I completely disagree with anything that misrepresents the truth, even in the name of some greater cause.  You can lie to people and get them to fall in line and do things your way, and your way may even be a better way.  But even so I will still disagree with those efforts and oppose them.

Second, I disagree with the idea that getting people to change their lifestyles is going to make that much of a difference.  We need to get rid of this mistaken notion that lifestyle factors are the major cause of illness and death.  They're not, and the numbers are pretty clear on this.  The major diseases causing illness and death, the ones responsible for the vast majority of the drain on the health care systems, are primarily diseases of aging.

Heart Disease and Cancer are the two top killers, and people seem to love blaming them on our modern lifestyles.  But lifestyle factors rate only a very tiny drop in the bucket compared to the major factors of age and genetics.  83% of those who die from cardiovascular disease are over the age of 65.  To illustrate the point, the difference in absolute risk for heart disease between those with a BMI above 25 and below (the cut off point for overweight) is about 2%.  The difference in absolute risk for heart disease for those above and below the age of 65 is about 31%.

In terms of relative risk it looks even more stark.  It's an 8% increase for weight, and a 1,550% increase for aging.  And the kicker is that the rates of both heart disease and cancer continue to decline, But if you ask most people, they'll probably expect the reverse to be true.  It seems to me that the way the public typifies the issue of lifestyle and obesity is seriously mistaken.

Now once again, don't get me wrong here.  I'm not saying that this is just aging and there's absolutely nothing you can do.  Certainly a balanced diet and an active lifestyle can help you live a little longer and keep you feeling happy and productive.  But it won't work miracles, the effects of these kinds of lifestyle choices are very moderate. 

But you often hear on TV people confronting others saying things like "If you don't change your ways you're headed for a heart attack before you're 40!".  Well, the data just doesn't back that up.  The vast majority of overweight people will not experience a heart attack before the age of 40, and it seems to me that portraying the situation in such stark terms does an incredible disservice to the truth.

And it's not just about weight, because we feel the need to criticize what people eat and do regardless of their waist size.  You see these observational studies coming out all the time claiming that this or that causes a certain type of cancer, usually with a relative risk of something like 50%.  But what you realize when you look at the numbers is that the incidence of individual types of cancer are exceedingly low.  If a certain type of cancer affects 0.1% of the population, and the rate is increased by 50%, in absolute terms that's a 0.05% increase in risk.

This is the kind of risk that people are often so afraid of that they'll completely eliminate the food in question from their diet.  And it's not necessarily even a true risk.  Observational studies are very blunt instruments, and a difference like this may very well be due to statistical noise and unforeseen confounding factors. 

This is what Ben Goldacre was talking about when he said that we're only seeing shavings in changes of risk.  These kinds of small numbers are the same for whatever lifestyle choice and disease you look at.  Cancer, heart disease, and diabetes are all by far primarily diseases of aging, and lifestyle factors are a tiny drop in the bucket.

But we look at a particularly meaty hamburger and laughingly call it a "heart attack on a bun".  We only say it half jokingly.  A part of us really believes that eating that burger is going to seriously affect our chances of getting a heart attack.  We particularly have these kinds of thoughts regarding things like the KFC Double Down sandwich, which I would argue is just a cute novelty food and trying it isn't going to hurt you.  But the public discussion seems to lean towards suggesting that this is what's wrong with our culture and all our health is going to hell in a hand basket.

We have this constant and misleading notion being put out there that if we could just get people to fall in line and have healthy lifestyles that we could dramatically reduce medical costs and cut the rates of death and disease by whopping margins.  But it's a complete myth, the numbers just don't support those kinds of projections.  Getting people to eat better and be more active can only have very moderate effects at best.  I think medical professionals often fool themselves  through what has been called the "White Hat Bias".  That's a bias in favour of feeling like you're helping people by bringing them critical warnings.  It's not that they don't have data to back up the fact that diet and exercise have a positive effect, they're just biased towards overstating the case.

And I think part of it is that the alternative health crowd has been very successful in running the public debate and they have been allowed to frame the issues their own way and have put standard medical practitioners on the defensive.  The common refrain is that standard medicine only treats the symptoms, not the cause, and they place no emphasis on prevention.  Well, that's wrong on all counts, and many medical professionals have fought back partly by pointing out that standard medicine has always recognized the importance of prevention.  The most important medical prevention if, of course, vaccines, but medical research into the effects of lifestyle factors is an important part of mainstream medicine.

And this has provided the impetus for medical professionals to portray themselves as enthusiastic supporters of lifestyle changes to prevent diseases.  And I believe that in their zeal to prove the alternative health crowd wrong, they've accidentally validated this alternative view of health which says that food has magic powers and that most diseases are caused by doing the wrong things.  People like this view because it's empowering to think that you might have a lot of control over your health, but the downside is that it tends to blame the victim for becoming sick.  But the real reason not to accept this view is because the data just doesn't support it.

There are so many clear examples of where the dangers of lifestyle are exaggerated and misrepresented both by the media and by the researchers themselves that the whole public discussion seems hopelessly skewed to me.  It gets kind of depressing to seldom see calls for moderation in the rhetoric involving this issue.  And from personal experience I know that if you do come out and say something you get accused of encouraging sloth and gluttony.

Now if you'll excuse me, I'm going to go veg out and drown my sorrows in a whole liter of ice cream mixed with a whole box of crushed Oreos.


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