New-trition

Just over a year ago I wrote a long post about nutrition that was probably the most popular / widely-read thing I've ever written.  Since then I've continued to read and learn a bit and I have a few additional thoughts to add.  Most of this is focused a bit more on the general / non-athletic population but it dovetails a bit with some of the athlete-focused stuff.

My biggest learning is that fat isn't bad for you, at least not to the degree to which it has been vilified since the 1970s.  In fact, high-glycemic carbohydrates are the likely cause of metabolic syndrome (the related conditions of obesity, diabetes, heart disease; as well as stroke) and likely contribute to other "diseases of western civilization" like most cancers.  The big turning point in my knowledge was Taubes (see below) but Cordain helped grease the wheels.

The party line about high-fat, high-cholesterol diets causing heart disease was incorrect.  Taubes calls this theory the "lipid hypothesis" for metabolic syndrome and he makes a very convincing case that this hypothesis is incorrect.  As an alternative he provides his "carbohydrate hypothesis" and backs it up with a dizzying number of research citations.  A high-glycemic diet combined with inactivity leads to insulin resistance in your tissues (mostly in the slow-twitch muscle fibers, according to Thompson) which leads to chronically high insulin which in turn causes your body to put on weight.  You may eventually become diabetic, too, if your pancreas can't secrete enough insulin to overcome the increasing resistance of your tissues.

Note that my general practitioner (sports medicine doc Bob Adams) and my triathlon coach (Matt Dixon) support eating the high-glycemic stuff during and immediately following exercise but recommend minimally-processed, low-glycemic stuff the rest of the day.  Matt advises that you think of Fueling (during & post-exercise) and Nutrition (the rest) as separate activities.  Taubes doesn't say much about exercise so this doesn't necessarily contradict his findings.

I want to go into a lot more detail on all of this but I don't want to bury you under a 10-page blog post so I'll break it up a little.  If you're eager to learn more, here is some recommended reading:

• My Microsoft HealthVault colleage Keith Toussaint recommended Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health by Gary Taubes. It is rather extensive, dense, scholarly… I started reading it before I went to Boulder last July and I don't think that I finished it until October.  The book is 600 pages long but 150 of those are research citations so there are about 450 pages of prose to wade through.  But it can be rather slow reading and is hard to read in short spurts.  Keith blasted through it in a week -- he's even more into nutrition than I am!
• Two lighter ones are The Glycemic-Load Diet: A powerful new program for losing weight and reversing insulin resistance by Dr Rob Thompson of Seattle and The Holford Low GL Diet: Lose Fat Fast Using the Revolutionary Fatburner System by Patrick Holford of Australia.  Both of these are more consumer-friendly than Taubes while touching on some of the same principles.  Each is written as more of a consumer "Diet Book" which can be a bit of a turn-off, but there is some intriguing info in there which generally agrees with Taubes.  You won't find as much clinical justification in these pages, but you'll get through 'em a lot faster.
• As I've said before, I really liked The Paleo Diet for Athletes: A Nutritional Formula for Peak Athletic Performance by Loren Cordain and Joe Friel. The central point of "paleo" is to eat foods that have been available to humans for thousands of years and to avoid foods that were invented recently.  The rationale is that it takes time for our bodies to adapt to different foods and that we haven't adapted to tolerate refined carbohydrates very well.  The "for athletes" modification says that the high glycemic stuff is great during and immediately following exercise but should be avoided at other times.  This is right inline with what my coach Matt Dixon teaches his clients.
• The Omnivore's Dilemma: A Natural History of Four Meals by Michael Pollan is a step away from all of this but still a fascinating read for somewhat different reasons. Pollan traces three food chains from source to table and the reader learns a lot along the way.  The corn-based food chain creates most of what we eat in the US today. Factory farms (which can be conventional or organic) grow monocultures of crops using truckloads of fertilizers and pest control, resulting in a rather high fossil fuel energy cost for each unit of food energy produced.  The "pastoral" or grass-based food chain was demonstrated via Joel Salatin's Polyface Farms in Virginia.  You really have to read that chunk of the book or a bit of their web site to really grok the awesome-ness of what they're doing.  In the final chunk of the book Pollan explores the hunter-gatherer food chain.  He looks at the environmental impact, health, and taste/enjoyment of meals from each of the three food chains.  A fascinating read which I highly recommend.