Now I'm going to spend a few posts on the primary hypotheses for the causes of the diseases of modern civilization. First up is the Carbohydrate Hypothesis.
From a macronutrient perspective the biggest change from the paleolithic to the neolithic is the addition of huge quantities of carbohydrates. Carbohydrates are not an essential macronutrient (you can eat zero of them and be just fine) and most sources of significant carbohydrates are not nutritionally dense (they don't have a lot of vitamins), so you lose nothing by cutting them out. In paleolithic man the main organ that regulated blood sugar was the liver, which manufactures glucose. In modern man it is almost exclusively the pancreas that regulates blood sugar, which responds to dietary carbohydrate (glucose) by releasing insulin into the bloodstream. The liver exerts a very fine control, but the pancreas exerts at best a very coarse control that results in sugar spikes and crashes. This ultimately leads to a screwed up metabolism where your insulin sensitivities are shot and all kinds of bad stuff occurs, often starting with obesity. There are links that can be made to many of the modern diseases using modern scientific evidence (e.g. cancer cells only grow in the presence of glucose). The worst offenders are probably the most refined carbohydrates in the form of white flour and refined sugar. This argument is best stated by Gary Taubes in his books, Why We Get Fat and What To Do About It and Good Calories, Bad Calories.
OK, so that is the statement of the hypothesis, but what do I think of it? Well, there is a reason that I am talking about this hypothesis first: I think it is critically important to talk about carbohydrates whether or not this is the true root cause of obesity and other diseases of civilization, because a low carb diet is almost certainly a useful medical intervention once your metabolism is screwed up. A huge fraction of Americans have a screwed up metabolism and if you are fat you are one of them (us). Overall I find the hypothesis very compelling, so I have not just adopted a paleo diet, but a fairly low carb paleo diet (avoiding potatoes, sweet potatoes, bananas, and grapes and the like).
Notice that if this hypothesis is true, a paleo diet easily avoids the harmful carbs.
Other potentially interesting carbohydrate hypothesis links:
- Gary Taubes' books do a fantastic job of explaining why conventional nutritional wisdom is wrong. Really wrong. But this lecture by David Diamond, Ph.D. is also great.
- This lecture is about the A-Z diet study. It was one of the first clinical trials to show the effectiveness of low carb diets.
- Go watch Tom Naughton's Fat Head video. You can stream it from Netflix or order a DVD from his site.
- The Ancestral Health Symposium just happened. Check out the talk by Dr. Michael Eades (who wrote Protein Power and other books on carbohydrate restriction). In the talk he tries to make the case for lower carbs in the context of paleo.
- The book New Atkins For a New You is excellent and contains a ton of really useful specific advice for watching carbs (although it is most assuredly not "paleo").
- Jimmy Moore has a great popular podcast, Livin' La Vida Low Carb.
- Dr. Robert Su has a medically oriented podcast and blog that is quite good (and a book that I just ordered).
- Here's a talk that Gary Taubes did at the invitation of Rivendell Bicycle Works (I own a Rivendell - Yay! Awesome bike.) There is other Gary Taubes stuff on YouTube too if you poke around a bit.