Complex Multi-Factorial Problems Tend Not To Have Simple Singular Causes

Perhaps it is my medical training that has me scratching my head in regard to Taubes’ argument that the only way to stop an epidemic is to unambiguously identify its cause. Not knowing the cause certainly didn’t stop Dr. John Snow back in 1854 when he determined that the source of the epidemic of fatal diarrhea plaguing London was a public water pump - the well of which had been dug just 3 feet from a cesspool. Though the bacterium Vibrio cholera had yet to be discovered, shutting down the pump stopped its fatal spread. Similarly I’m glad that Taubes wasn’t around then to discourage British sailors from bringing limes on their sea voyages because scurvy’s root cause had yet to be identified.

My head also needs some scratching when considering Taubes’ assertion that ultra processed foods aren’t drivers of chronic disease because there are examples of populations who had sugar and white flour in their diets but didn’t suffer diabetes or obesity. Putting aside the fact that sugar and white flour by themselves don’t meet the definition of ultra-processed foods (they instead fall into the category of “processed culinary ingredients”), pointing one’s finger at specific traditional populations’ diets to make a point is akin to trolling PubMed to find a study that agrees with you. I’m certainly not about to point to Hadzas’ diets, with 68% of their total calories coming from carbohydrates and 22% of those coming from honey, as being a useful means to prove that diets high in carbohydrates and honey are protective, the Hadzas’ lack of diabetes or obesity notwithstanding.

Perhaps it is also my medical training that has me recognize that unlike Taubes’ strawman suggestion that my advice is meant to “maximize” my patients’ happiness, my patients’ happiness does in fact matter, especially in regard to their diets, as food is not simply fuel. Food as pleasure is part of the human condition. We use food for comfort, for celebration, and no doubt as the world’s oldest social networking tool. It’s for these reasons, and the fact that we can’t simply stop eating, that Taubes’ smoking analogy falls short.

And what of Taubes’ assertion, despite his not likely ever having worked with people on behavior change, that the way doctors help patients is to, “give them the knowledge and let them decide”? While Taubes’ apparent vision of a physician is as a finger-waggling patriarch that provides black and white absolutist advice, real clinicians take the time to understand their patients and their lives. Real clinicians also appreciate the benefits of harm reduction. We understand that healthy living is challenged both by our modern toxic food environment as well as by a patient’s personal, socio-economic, and medical realities. We tailor our advice to each patient accordingly. And no, doing so is not seen as condescending.

Coincidentally, just after reading Taubes response I had the pleasure of seeing a patient who has taken to heart the advice to live the healthiest life that he can enjoy. Now no doubt he’s received a great deal of other advice from my office, but we’ve never asked him to cut out sugar, and he’s not on a low-carb diet (though some of our patients are - the ones who enjoy low-carb diets enough to sustain them). I asked him if I could share a bit of his story and he agreed. When we met in August he weighed over 300lbs and had just been discharged from the hospital following his admission for out of control type 2 diabetes. He was on 70 units of long acting insulin, along with a number of oral hypoglycemic drugs. His sugars were a mess; even with those 70 units of insulin and multiple oral hypoglycemic drugs, they were regularly clocking in at over 4 times normal. Six months later, he has lost over 40lbs, increased his exercise, improved his diet, is totally off insulin, and has sugars that are in the normal range. Most importantly, he doesn’t feel deprived. He is enjoying his life, and consequently he is confident that he’ll be able to sustain the behaviors he’s adopted.  And his story is not even remotely unique. Sub-total weight loss, coupled with improved attention and guidance on big ticket healthy living behaviors, regularly leads to dramatic clinical benefits.

Which brings us, finally, to Occam’s Razor. Occam’s Razor dictates that the most plausible cause is likely the right one, but it’s important to point out that the most plausible cause is not necessarily the simplest. And here the most plausible cause for our rising rates of obesity and chronic non-communicable diet related diseases, as I elaborated in my first essay, is that we are eating much more than we ever have, that what we’re eating has changed dramatically, and that the world now more than ever markets and pushes nutritional chaff at every turn. These are causes that Taubes’ rebuttal did not address, and causes that would matter to anyone who understands that it’s not just the quality of calories that matter, but also their quantity.

While there’s no argument that sugar plays a real role in all of the above, and also no argument that it’s in public health’s best interest to work towards encouraging and enabling a societal reduction in the excessive consumption of sugar, dumbing everything down to one nutrient in an attempt to provide a simple solution to a highly complex and multi-factorial problem does a disservice to thoughtful public health strategies and to individual patient care.

Black and white is much more useful to dogma than doctors.

Also from this issue

Lead Essay

  • Gary Taubes tells a tale of unintended consequences: When the U.S. Department of Agriculture issued the first federal dietary guidelines, it may have hoped to steer Americans away from excess fat and toward a diet of whole fruits and vegetables. But this did not happen: Overwhelmingly, Americans turned to processed, sugary, and high-carbohydrate foods instead. The result was an epidemic of obesity. Meanwhile, dietary science continued to evolve. The case against fat weakened significantly, while the case against sugar strengthened. Yet scientists do not deal in certainties; their findings come with varying degrees of confidence, a state of affairs that public policy has difficulty reflecting.

Response Essays

  • Stephan Guyenet says Americans can’t blame government nutrition advice for their overconsumption of sugar. Dietary guidelines issued in 1980 didn’t recommend substituting sugars for fats; they recommended decreasing consumption of both. Americans, however, started eating more sugar anyway. Nor is it clear that sugar is to blame for obesity, because American sugar consumption peaked in 1999 and has declined ever since. Meanwhile, obesity has continued on a steady upward trend. Sugar is one part of a larger picture that explains American obesity, diabetes, and heart disease; it is not the sole culprit.

  • Yoni Freedhoff says that the public policy debate about nutrition would benefit from a practical, clinical perspective. American’s eating habits have changed a lot since 1977, and while sugar is a part of that change, it’s only one part among many. Americans eat more meals outside the home. They eat more pre-packaged ready-to-eat meals. They eat larger portions. And they eat many more calories altogether. The case against fat in the 1970s and 1980s was certainly flawed, but those flaws can’t be blamed for Americans’ poor dietary choices in the meantime, and, what’s worse, today’s critics of sugar may be replicating some of the same mistakes.

  • Terence Kealey praises Gary Taubes for being willing to submit his nutritional theories to empirical testing. Rather than trading on influence and suspicion, Taubes has articulated a hypothesis, namely that sugar is to blame for metabolic syndrome, and he has called for further research in the area: not panic, not grandstanding, but the same sort of testing that brought us to become skeptical of earlier conclusions that have now been rejected. If the sugar hypothesis is correct, it will stand the testing. If not, it deserves to be rejected. Public health and government guidelines should wait and see, and follow the research.