Thursday, March 22, 2012

Low-Carb or Low-Fat? It Depends..

 How do you know whether to eat a low-carb/"Atkins" diet, or a low-fat/"balanced" diet? If low-carb, how low-carb? If low-fat, how low-fat?

The Problem with Paleo

The problem with the Paleo movement is that evolution did NOT stop 10,000 years ago. [Quick primer on natural selection: “survival of the fittest” does not mean toughest or most cruel, but the combination of inherited qualities that best fits the local environment; if the environment changes a significant amount in a short time, and remains changed, evolution speeds WAY up for a little while, then slows way back down again (this is called “punctuated equilibrium.”).] 

As Gregory Cochran and Henry Harpending argue in The 10,000 Year Explosion, agriculture provided both of the necessary ingredients for evolution: the huge increase in population (more food) and the stimulus (different foods = different environment).

However, as Jared Diamond explained in Guns, Germs, and Steel, although wheat farming began about 10,000 years ago, it took agriculture over 4000 years to spread from the Middle East to Northern Europe (the growing season was too short, so they had to develop rye and oats). Agriculture started independently around the same time in Asia, but didn't become widespread in Africa or the Americas until much later. It's not like all humans suddenly switched over to farming in the year 8000 BC. Therefore, we as a species are still adapting to the foods of agriculture, and different people are adapted different amounts (depending on how long their ancestors have been farming).

The Standard, or Gauss-ian, Distribution

Many qualities and characteristics of individual humans are distributed throughout society in such a way that, when plotted on a graph, they form a bell-shaped curve. Some, like height, are inherited. The average male US citizen is 5'10”, and the incidence of lower and higher heights drops away from that center point, with most men being only a few inches different in either direction; of course, there are a few percent on either end of the graph who are more than a few inches shorter or taller. This example is widely recognized.

There is another example which our society has not recognized, but desperately needs to: the distribution of inherited need for different macro-nutrient ratios.

  • The average person needs 40% of calories from carbs, 40% from fat. Most Americans got about 45% carb/40% fat (only leaving 15% for protein) before the obesity epidemic; we now know that protein is better at more like 20% - it's by far the most satieting macronutrient (reduces hunger), and not only are your skeletal muscles made of pro, but all the soft tissues of your body (except brains), and you also need it for enzymes, hormones, and neurotransmitters. 
  • At one extreme end are people who inherited a need for a ketogenic diet (if you don't get epileptic seizures if you don't eat a ketogenic diet, then you did not inherit a need for a ketogenic diet.)
  • At the other extreme end are those who inherited a need for a vegetarian diet. (There is not any human for whom a vegan diet is the most healthy.)
  • About 1/4 in from the keto end are people who inherited a need for 50% of cals from fat/30% from carb.
  • About 1/4 in from the veg end are people who inherited a need for 50% of cals from carb/30% from fat.

Healthy Fats

The healthy dietary fats for humans are: animal (preferably organic), nut (peanut is not a nut), and fruit (olives/olive oil, coconut/oil, avocado/guacamole). All other dietary fats (“vegetable” oil) must be strictly limited, or eliminated if possible.

The science NEVER supported the “arterycloggingsaturatedfat” BS, which I cover more extensively in my “Calories vs. Hormones” article.

What to Do

IMPORTANT: You are NOT free to choose which division of macros is right for you, and your body will NOT “adapt” to whatever you feed it. You inherited a need for a certain division of macros, and you must discover where on the graph you are, so you can eat the diet that's right for YOU.


  1. Hi, I find the bell curve distribution for macronutrient ratios very interesting. Is there any supporting data for that? In the paleosphere, there's a huge debate about "safe starches" versus VLC, and nothing seems to be conclusive yet. Many report feeling better after adding more carbs but I'm still unconvinced about the need for dietary carbohydrate, considering that the body is capable of producing its own. I'm very curious as to how you came up with this theory.

    1. Hi Karthi,

      that debate is exactly why I wrote this post. No, I do not know of anyone else out there saying it (no pubmed refs, sorryz).

      I observed that some people do well on LC, others on low-fat, most somewhere between; it's "original research" as they say.

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  3. Anonymous1:21 PM


    Is there a simple way to tell what a person's optimum macronutrient ratios are?