Paleo vs. Primal vs. Atkins, Thermodynamics and A Calorie Is Not a Calorie

“In this house, we obey the laws of thermodynamics!” – The Simpsons


The Boy during a Primal phase.  Brains are Primal, right?

What does a diet do?  There are thousands (if not millions) of different diet books in print, each with a new diet, and they appear nearly hourly.  Diet books, perhaps, due to sheer number density, might form an information black hole that sucks in all other books.  Even Dilbert (LINK).  Then I would be sad.

The purpose of a diet should be twofold – to produce optimal nutrition at a healthy weight.  And make no mistake, those shiftless British (LINK) have done a study of British medical records and determined that . . . it sucks for your health to be overweight.  Being fit and fat?  Probably (according to the Portuguese guy I accosted on the street while yelling about these results in a threatening monotone) a pretty little lie we tell ourselves.

Out of this vast galaxy of diets, I’m picking out five for further discussion and follow up with a description of what thermodynamics says about them.  I pick these because they seem to be the main pattern of diets today:

  1. Vegetarian/Vegan: No one actually does this, but there are millions of people professing to like tofu instead of ribeye, and wanting you to have a meat-substitute brisket in the smoker.  And a vegan?  They will change any discussion that’s occurring in order to bring up the fact that they’re a vegan.

John Wilder:  “I hear that there might be life on Mars.”

Vegan:  “I hope it’s a vegetable, because I’m a vegan.”

It is my prediction that veganism/vegetarianism will catch on like wildfire when rare filet mignon and bratwurst are declared vegetables.  Sweet, meaty, fatty vegetables.


  1. Low Fat: Very popular in 1977 when your Mom took up smoking to impress that guy who had the cool Camaro®.  Still popular with the makers of sugar!, high-fructose corn syrup©, breakfast cereal®, and Pop Tarts™.


Oh, and turkeys!  Turkey bacon, turkey burgers, turkey cheese, turkey sour cream, and turkey mint julips.  Everything that’s come in about this diet indicates that it’s wrong on every possible level, including being responsible for Angela Merkel’s haircut.


  1. Paleo: The basic theory is that the human digestive system has simply not caught up to agricultural life, unlimited Twinkies®, unlimited couch time with Halo 47©, and unlimited calories.  Since our digestive system hasn’t come under significant evolutionary pressure, we’d be better off drinking elk blood in the forest.

The Paleo diet allows no: grains, sugar, beans, dairy, potatoes, processed food (I’ll miss you, dear bacon), refined vegetable oils, salt, alcohol, and good heavens, coffee.

That’s unnecessarily cruel!  No coffee?  What would I do for a personality?

A good website on Paleo is here (LINK).

Real short version?

2-0-1-7 tomorrow, out of time, so tonight we’re going to eat like it’s 10,099.


  1. Primal: A lot like Paleo, but recognizes the central role of coffee to my central nervous system.  Additionally, in comparison to Paleo, it’s more of a complete lifestyle, including exercising and having relationships like a Neolithic tribal dude.

The Primal diet is a lot like the Paleo diet, but you can have dairy, coffee, some potato, coffee, beans are okay-ish, coffee, and wisely chosen dietary supplements.  Did I mention coffee is okay?

The definitive website for Primal is here.  (This is also the definitive post.)

  1. Atkins® (or “keto”): Nuke the carbs from orbit, it’s the only way to be sure.  Lifestyle?  Who cares.    THE.  CARBS.  20 grams or less of carbohydrates in some phases of the diet.  Bonus?  Eat all the bacon.  And drink all the coffee.

How does a diet work to help attain or maintain a healthy weight?

First:  What’s a Calorie?

In nutrition, a Calorie is a measure of the chemical energy stored in food.  It has a specific scientific definition as being “the amount of energy required to raise the temperature of one kilogram of water by 1˚Centigrade.”  So, if you weighed 750 kilograms (more than 1,500 pounds), you just have to walk into a fridge and reduce your body temperature by one degree, and when you warm yourself up, presto, a cheeseburger vanishes from your thigh!

In reality, there’s enough thermal energy in 10 plain chocolate M&M’s® to raise a big cup of coffee from room temperature to a pleasantly hot 130˚F.  When I tried this experiment at home, the coffee stayed cold, but got chocolatey after a day or so.  Then moldy.  Then The Mrs. yelled at The Boy and blamed him for the mess.  Whew!  It’s great having folks who’ll take the fall for a fiver.

The way they determine the Calorie content of your food is (I’m not making this up) by burning it in a really sensitive oven and measuring how much heat it gives off.

But your body doesn’t spontaneously combust, no matter how many pancakes you eat, so I’m thinking that the body may have a tiny lit furnace someplace south of your stomach, except for Pugsley, since sometimes he smells like burning tires.

So, food is used differently than that, as I started to discuss in a previous (LINK) post.

One rule of thermodynamics (thermo, from the Greek, meaning “a class in college” and dynamics, also from the Greek, meaning “that came from Hell”) is that you lose efficiency every time you convert energy from one form to another.  In the conversion of food from chemical energy to useful human energy, fat (as in yum!) and carbohydrates (as in sugar, also, yum!) are about the same, requiring about 5% to 15% of the energy consumed to digest and use.  In the world outside of squishy human bodies, that’s exceptional!  A human body is 85% efficient when running on Ding-Dongs®.  A car is only 20% efficient when running on gasoline.  You’re super efficient!

That’s also why you’re fat.  I’m willing to bet the human body developed a craving for sugar and fat because it was so efficiently converted to “keeping you alive” that when you could expect to find very little food, you were drawn to the best stuff.

When you convert protein (also yum, as in the rest of the steak!) to energy, the pathway is much less efficient, converting 65% of the energy to useful activities, like typing and drinking scotch.  Still this is three times better than a typical gasoline powered car.

Like Justin Beiber, sugar has a much darker side – it spikes insulin output, which is required to get sugar into cells so it can get to work.   But insulin is also the hormone that, in abundance, tells your body, “Hey, back up the truck with all the energy you can’t use right now.  We’ll just turn it into fat.”

A recent JAMA (Journal of the American Medical Association, or Jamaican Ancestral Music Annual, I forget which) article says that people on ultra-low carbohydrate diets burn 100-300 more Calories per day than those same people on other diets.

I think Dr. Atkins just dropped his microphone and walked off the stage.

My conclusion is this:  The Paleo and Primal diets both restrict carbohydrates very effectively, but not as well as the Atkins diet, which is as single minded as a puppy on a pork roast in elimination of carbohydrates.

A potential optimum?  Use Akins to get to a healthy weight, then transition to Primal as a lifestyle.  Atkins is the journey, but Primal is the habit, and, of course, the lovely, lovely coffee.

Comments?  Your mileage?

Reminder:  JOHN WILDER IS NOT A DOCTOR.  Consult yours before following the patently absurd advice offered above.

Author: John

Nobel-Prize Winning, MacArthur Genius Grant Near Recipient writing to you regularly about Fitness, Wealth, and Wisdom – How to be happy and how to be healthy. Oh, and rich.