Thursday, July 14, 2011

Gorillas, Cows, and Evolutionary Biology: Debunking Fat Phobia

Artwork by Jennifer McCully 

Ruminants (cows, goats, etc.) are plant-eating herbivores.  They eat no meat, so their fat intake must be very low, right?  Not so!  According to research displayed in the book, Perfect Health Diet, ruminants indirectly eat lots of short-chain fat.  Their special four-stomach digestive system promote bacterial digestion of plant foods.  The by-product of this is fat, which is utilized by the liver to repackaged and sent throughout the body.
After processing by the digestive tract, ruminant macronutrient ratios are: 0% carbs, 17% protein, 80% saturated and monounsaturated fats -- 70% short-chain, 10% long-chain, 3% polyunsaturated fats.
Note that there are zero carbs available for ruminants after food is digested by bacteria in their digestive tract.

A similar process occurs in gorillas, another mostly vegetarian mammal.  Gorillas only have one stomach, but they have a very long colon.  Since it is so long, it can store lots of bacteria, which again ferment plant materials into fats.  
As a result, gorilla macronutrient ratios are approximately as follows:  16% carbs, 20% protein, 62% saturated and monounsaturated fats, 2% polyunsaturated fats.
The authors of Perfect Health Diet, Paul Jaminet and Shou-Ching Jaminet, also show that all wild mammals have similar macronutrient profiles:
0% to 16% carbs, 15% to 25% protein, 56% to 77% saturated and monounsaturated fats, 1% to 14% polyunsaturated fats.
So where do humans fit into this?  Given that humans have larger brains than other mammals, and brains function solely using glucose (as opposed to the rest of the body which can also be fueled through fat), more carbs are needed, though not a substantial amount.  Fat still dominates.

Also, since humans have neither a long colon (at least compared to other animals like gorillas or pigs), nor four stomachs, they cannot ferment as much plant material into fat, and therefore should have more fat directly in their diets.
This predicts the optimal human diet to be about 20% carbs, 15% protein, 60% saturated and monounsaturated fat, and 5% polyunsaturated fat.
In comparison, the standard American diet (SAD) typically averages 52% carbs, 15% protein, and 33% fat.  

Needless to say, eating fat is an evolutionary and biological reality, it is not scary!  For clarity's sake, I should not generalize:  Fat is not scary if it is of the right type and proportion.  Most Americans eat a lot of polyunsaturated fat, specifically omega-6 polyunsaturated fat, primarily in the form of vegetable oil.  This kind of fat is in virtually all processed food and many cooked foods.  This is not in line with biological evolutionary evidence (nor is SAD's excessive carbohydrate content).  Needless to say, all mammals use fat as food either directly or indirectly.

Now, does this mean there is one optimal human diet?  Of course not--absolutely not!  What works for one type of body may not work for another.  The human body is the ultimate barometer.  No one cares about your health more than you.

- Teddy Grahams

The authors of Perfect Health Diet have their own blog.  It can be found here:

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