Going Big As An Enlightened Hedonist

Imagine the following thought experiment. We want to know whether broccoli or asparagus is the healthier food. We take 1 millions people and assign them to one of two groups. One group (500,000 people) is instructed to eat one large serving of broccoli at least five times a week. The second group of 500,000 is instructed to eat asparagus five times a week. We follow these two groups for, say, 40 years and we measure their health status. (We would need that many people and follow them for that long a time because whatever the difference, it would be small and could only be detected by such a vast experiment.)

And after 40 years we have our answer: Eating broccoli rather than asparagus results in a 0.0017% relative reduction in overall cancer rates and a 0.0043% reduction in cardiovascular disease. As a result, the people in the broccoli group lived an average of 13 hours longer than the people in the asparagus group. I daresay that if you were to read this study it’s not very likely that you would take these results to heart and make the appropriate broccoli>asparagus conversion.

I have made up this entire scenario of course, so what’s the point? If we were to conduct this kind of study on every possible food type or combinations of foods we would find that in every comparison one thing will be superior to another. If two things are different they will have different effects—its’ simply a question of having a large enough sample to be able to measure that difference. But what would we do with these thousands, or tens of thousands, of pieces of information?

In the world of real science we actually see differences of this magnitude and smaller, and we are asked to take them seriously. But we should not. If we are going to be Enlightened Hedonists we are going to have to make some distinctions. There’s not going to be much pleasure in food or anything else if we devote our lives to fine-tuning, calibrating, regulating and otherwise attempting to optimize our diets and other health-related behaviors. We’re going to have to decide that some things are important and other things are not.

But it turns out we humans are not very good at such calculations. Our intuition and common sense fail us when we try to estimate risks and benefits of activities that affect our health. Consider this example:

Over 4000 women were surveyed and asked to imagine the following scenario..

Think about a group of 1000 women who are 50 years old and then imagine their health over the next decade. By the end of the decade estimate how many women had died and how many of them died specifically of breast cancer. And think about this scenario both among a group of women who received mammograms during this decade and a group who did not.

Here’s how the women responded:

 

  Without Mammograms With Mammograms
Still alive at the end of the decade 796 876
Died of breast cancer 160 80
Died of other causes 44 44

 

In other words, the perception is that the naturally occurring rate of breast cancer death during the decade of the 50s is 16%. This rate can be cut in half to 8% if women use mammograms. Two things jump out from this. 1. Women perceive that the risk of dying from breast cancer is very high; 2. Women perceive that mammography is very effective at reducing that risk. Out of 1000 women, 80 will have their lives saved through mammography.

Unfortunately these perceptions are wildly inaccurate. Or I should say, fortunately these perceptions are wildly inaccurate. Fortunately, because the actual risk of dying of breast cancer is about 40 times smaller than the perception—only about 4-5 women per thousand will die of breast cancer during this decade of life. And the actual benefit of mammography? It is very, very small, so small that accurate measurement is difficult. The number of lives saved is probably somewhere between zero and 1. Let’s call it 0.5 lives saved. If you do the math it turns out that the average woman will extend her life by about 3 ? days by getting mammograms. Well, it’s more than the hypothetical 13 hours of extra life from eating broccoli, but still…

(The full analysis of the relative benefits and harms of cancer screening is rather more complicated, and more discouraging, than I’ve presented here. This issue will be revisited in the future.)

While this study specifically examined the perceptions about breast cancer and mammography, these findings reflect a more general truth about the way people tend to think about health. That is, we tend to vastly overestimate the risks of becoming ill from any specific malady. And at the same time we also vastly overestimate the effectiveness of efforts to prevent the malady. Taken together these two misperceptions lead us in the direction of apprehension and dread worrying about our health and then to desperate measures trying to deal with this perceived problem.

No, this does not cause pancreatic cancer
No, this does not cause pancreatic cancer

Recently a well publicized study found that eating cured meat (e.g., bacon, salami) increased your risk of getting pancreatic cancer (one of the deadliest of all cancers) by 19%. One might think, “I love bacon, but pancreatic cancer is really awful. If I can reduce my risk of the by nearly one-fifth by simply avoiding bacon, well, I guess that’s the price I have to pay to be healthy.” In fact CBS News reported on this study with this headline:

Pancreatic cancer risk increases with every 2 strips of bacon you eat: Study

But let’s do the math.

The incidence (number of new cases per year) of pancreatic cancer is about 12 cases per 100,000. Over a 20 year period that risk translates to a 0.24% chance of an individual getting pancreatic cancer. This increases to 0.28% by eating bacon, according to the study. If we assume that all pancreatic cancer is fatal and if we assume that each fatality results in 20 years of lost life, that means that for every year that you avoid bacon and related meats you add…3.5 hours to your life.

(It is another question entirely whether or not we should accept study findings such as these at face value. As a rule, we should not. Almost always these values are derived from observational, not experimental studies. As such they are very unreliable and almost always err in the direction of overstating the magnitude of the risk. Almost certainly bacon/pancreatic cancer connection doesn’t exist at all.)

One might expect that the science/health journalists who report on these studies would do the math, but they never do. (They are really quite clueless, but that’s another story.) As an Enlightened Hedonist you may have to do the math yourself from time to time. No, you don’t have to calculate the number of hours or days that might be at risk. Here’s a quick rule of thumb that you can use: If you hear that risk factor X increases (or perhaps reduces) the probability of a condition by anything less than 50% you can safely ignore this information. It’s literally meaningless. Even for effects in the range of 50% to 100%, when you do the math it’s still something of a “meh.”

An Enlightened Hedonist looks for big effects. How big is big? As an example, the risk of lung cancer is increased by about 2700% among cigarette smokers. This along with other smoking-related illnesses results in an average loss of one decade of life among smokers. 3,650 days. More than 1000 times greater import than getting or not getting mammograms, eating or not eating bacon or a myriad other trivial health risks.

If I may offer a small piece of advice to my many friends in CrossFit—Stop Sweating the Small Stuff!! So with apologies to David Letterman, here are the Top Ten Reasons to ignore health factors with small effects:

  1. Small effects are often no effects;
  2. The number of possible factors with small effects is virtually limitless;
  3. The smaller the effect, the less likely that it actually exists;
  4. A small positive effect may be offset by a small negative effect in a different domain of health;
  5. Your life will be far more enjoyable if you ignore small risks;
  6. We don’t know enough about any of these small effects to actually know whether or how to take advantage of them;
  7. They distract you from the big effects;
  8. You are smart enough to do the math;
  9. In the end you will fail to realize any real benefits chasing after small effects;

And the #1 reason to ignore small effects:

1. Bacon!

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