Friday, July 12, 2013

A Few Questions About Ketosis

Over the past few years as the health-food craze has gained momentum, we've seen several waves of faddish diet strategies emerge into the broader society to receive institutional attention by marketers, intellectuals, and policymakers (gluten-free is so hot right now). Seeing this boom-and-bust pattern (based mostly on the difficulty of assessing causation in big epidemiological studies) some commentators have adopted a detached position on nutrition, emphasizing skepticism of any particular weight-loss strategy. The appreciation of the extreme complexity involved in issues of obesity and health is long-overdue, but skepticism is not the only response to the failure of empirical studies to tell us what's what in nutrition.

A popular alternative approach is to use a small number of case studies: we all know people who have dabbled in various health schemes and offer first-hand accounts of their efficacy or failure. The problem here is with generalizing idiosyncratic experiences to broader populations.

A third approach is to mostly eschew data and instead focus on the mechanisms involved with diet and weight-loss. It is here that we find the justification for perhaps the most provocative new health "fad": the ketogenic diet. According to this strategy, high levels of carbohydrates in the diet encourage large appetites and weight gain (mostly via increased insulin secretion). To get healthy one should mostly eliminate carbohydrates and sugar from the diet to push the body into a metabolic state known as 'ketosis', where fat provides for most energy needs, the rest coming from protein and green vegetables.

Essentially the ketogenic idea is a more radical version of the Atkins or paleo strategies, but a better interpretation would be to view it as the collection of value-free mechanisms which underpin these more popular fad diets. The strategy rests solely on the power of its theory, namely the biology of fat metabolism and the logical refutation of the popular 'calories-in/calories-out' conception of weight-loss. Now clearly, relying on theory alone has its problems: looking back at the history of ideas, most theories have been proven wrong, often disastrously so. And yet because of the inability to predict when and how existing paradigms will get overthrown and replaced, curious people have no choice but to engage in useful delusions to further the random walk towards better understanding.

That said, learning a bit about this ketogenic thing (a good urtext is Why We Get Fat by Gary Taubes; nice podcast here) prompted more than a few questions:

  1. To what degree does the sciency branding of 'keto' dazzle people into thinking it's more reliable than other health approaches?
  2. To the extent that the ketogenic diet is a logical extension of an analysis that claims to explain the efficacy of all diets, how do different existing fad and ethnic diets 'simplify' to the same framework. Example: can we really show that French and Japanese cuisines (both relatively healthy and filled with carbohydrates) work with this theory?
  3. Although the arguments supporting a causal connection between carbohydrate intake and body fat seem compelling, it may be a logical fallacy to assume that the metabolic state of ketosis is optimal compared to lesser degrees of carbohydrate restriction (much of the ketogenic analysis ignores the possibility of trade-offs between different dimensions of health).
  4. To what extent do the [few] empirical claims about the benefits of ketosis rely on extrapolating from existing studies of low-carb diets, and to what extent is that jump fallacious?
  5. To what degree does the gamification benefit confound the stated biological mechanism viz. keto's remarkable ability to induce stick-to-it-iveness in dieters? i.e. Eating out is like a Where's Waldo of acceptable foods, which can be fun or miserable.
  6. To what degree is the binary feature of ketosis (i.e. bad physical side effects when you cheat) a feature or a bug? It provides an incentive to stick with it, but only for people who... stick with it. On some margin it will turn off potential dieters because it severely constrains one's flexibility: if you find yourself at a social function where you must cheat to conform to social norms, you'll be unfairly punished.
  7. To what degree does a 'keto' regime induce regular scheduling and more domesticity in lifestyle? i.e. cooking more food at home makes going out harder; camping, traveling, and seizing opportunities for cultural experimentation are more difficult.

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