Concluding thoughts on Activity and Diet

 In my two previous posts (here and here), I discussed the relative merits of two long-standing public health initiatives that the US Government has in place.  To summarize, the Physical Activity Guidelines are, I would say, politely ignored by the various medical professions that most people come into contact with (family doctors and nurses).  My theory for that is that I would imagine that most conditions that family doctors treat don't respond to physical activity.  I'd estimate the most common complaints in a doctor's office are Upper Respiratory issues (colds, flu, sinus trouble) and digestive issues (constipation and diarrhea).  None of those will be helped with physical activity, so it doesn't come up.  

In contrast, the Dietary Guidelines are hated and scorned by everyone.  Doctors may think that physical activity is a Good Thing, but maybe not relevant to the complaints that brought his patient in today.  In the Physical Activity Advocacy world, there's a phrase "Exercise is Medicine", which  most doctors probably roll their eyes at but let pass.  There are people promoting the "Food is Medicine" message, but those people are largely dismissed as quacks and nutters.

The Physical Activity Guidelines are pretty simple: "Move! And if you're already moving, then move more."  How you  move is is largely up to you, they even have a nice webpage to help you figure out new ways to fit physical activity into your day.  By contrast, the Dietary Guidelines are very complicated.  Rather than simple recommendations like "reduce salt" or "reduce sugary", they promote "Dietary Patterns", which make little sense.

And yet, diet is complicated.  People's dietary choices are often determined by culture and asking them to change their diets is like telling them to change who they are.  Sometimes people do change their diets to change who they are (to identify with a different group, for instance).  Cultural diets are common: different nationalities have their own culinary style, different religions have different dietary restrictions, and even within the same broad culture, subcultures exist.  As I type this, the "vegan wars" seem to have fizzled out, where obnoxious vegans would flood social media with anti-meat or pro-animal-rights posts and equally obnoxious carnivores respond with pictures of bacon-wrapped bacon and greasy barbecue (and as a Texan, I know well the pride that comes from making a good barbecue).  But the point is that diet is intrinsically tied to identity and asking people to change that has to be done with sensitivity and skill.

Furthermore, studying diet is complicated.  Exercise is a thing you do.  And it's relatively easy to record someone doing it.  You can make them come to your lab or a gym a specific number of times per week and record how many calories they burn while there.  And you don't care what they do the rest of the time.  Or you can fit them with an activity tracker and download their activity throughout the study period.  But diet is just as often something you don't do.   Unless you plan on housing and feeding people for an extended period of time, you can't be sure that they aren't sneaking off to McDonalds and throwing your carefully crafted meal plan in the trash.

And of course, everybody lies about their exercise and diet.  So it's important to have an independent measure of either one.

I gave the Physical Activity Guidelines low marks for being vague.  "Moderate" vs "vigorous" activity.  While I get the fact that they can't specify a heart rate level or number of steps or anything else that requires special equipment to measure, it's still a problem since most people will over-estimate how much effort they put into their activities.  But the Dietary Guidelines are even worse with a bunch of complaining about how poorly people eat and how sick they are as a result, but no actual estimate about how much better off people would be if they ate correctly.  

By training and profession, I'm an engineer.  Engineering is based on the physical sciences, and there's an adage that "unless you can measure it, you don't really understand it".  Engineers don't go for "this is better" or "this is faster" or "this lasts longer".  We want numbers.  Another adage I've heard is "If you can't test your theory, it's not physics. It's philosophy." The Dietary Guidelines definitely are not physics, of course, but I can't shake the attitude that they aren't showing numbers because they don't really believe what they are telling.  

Another similarity between the two is the relative benefit.  The Physical Activity Guidelines claim that exercise will benefit just about everything, but most benefits are around 70% to 80% of the lazy baseline.  Looking at mortality or cancer risk or diabetes risk, the score is always about the same: 70%-80% better when exercising.  

Even though the Dietary Guidelines are light on  numbers,  a review of other literature also indicates about a 70%-80% reduction in cardiovascular disease with a proper diet.  So let's go with that.  Again, this is not nothing, but it's not a cure-all.  It can have a huge impact on a large number of people, but not likely to change society.

So two very different programs, but a similar result.  Again, what do you expect? Something that's free that has a 100% success rate?  Life isn't like that.  A 20% reduction in risk is pretty good, all things considered.

Finally, I Flunked the Dietary Guidelines because they are ineffective.  Just look at all the couch potatoes around.  Given the increased work-from-home during the pandemic, that has surely gotten worse.  But of course, I can't actually say that the Dietary Guidelines are useless or even harmful because I have nothing to compare to.  There's not another United States, with the same culture, lifestyle ethnic mix and level of income that has different dietary customs and guidance that I can use as a control.  We've gotten fat and lazy with the current system in place, and so can't say if things would be better or worse with a different scheme.

As a last point, I might just address a question that probably should have been addressed at the beginning: why have these programs at all?  I mean, why have the Government, which is normally busy abusing its citizens in myriad other ways, take the time and effort to release these guidelines, knowing full well that they will be ignored at best and ridiculed at worst?  I have no answer for that.  Certainly as a major insurer, in the form of Medicare and Medicaid, the government has an interest in keeping health care costs down.  But, generally speaking, the government does not exhibit any trace of altruism towards its citizens.   Its just another case of the Government knowing better than the rest of us and wanting to make sure we know who's boss, I guess.