Quick, how long did the energy from the last meal you ate last? An hour, two hours? How long did it take until you got hungry again? The answers to these questions has a lot to do with the macronutrient content of what that meal contained. And you had better believe this has serious implications for the optimal survival foods for a disaster situation.

Three types of calories, two forms of energy

As we know, all calories were not created equal. Glancing over any nutrition label, you are likely to see calories at the top. Everything underneath can be classified into calories from one of three main sources, protein, carbohydrates, and fat. The calories from these three categories will always add up to the total calories in a meal because they are the units of energy which make up a food. All roads lead to the same end destination: usable energy for your body.

Fat based metabolism (ketones)

Earlier in human history, our ancestors used to roam the lands following herds: buffalo, gazelle or even mammoth. We were hunters, and we supplemented this diet with herbs and roots we could forage. The meat we would eat from these animals contained a lot of protein, but most of the usable calories came from fat, which is a lot denser in energy. Fat is converted into molecules called ketones in the bloodstream which are used by cells as fuel. This energy would provide a sustained burn for constant energy; being in a state of using fat as fuel is known as ketosis. When we had a big kill, or when we found fruit to harvest, our bodies could store these extra calories as fat.

Carbohydrate based metabolism (glucose)

In primitive times, carbohydrates were scarce. Before civilization, grains were not harvested or processed in an organized way. Crops were not raised as we were nomads. Carbs were available very rarely and would have to be stored as fat for the lean times ahead if they were found. Carbohydrates break down very fast into a sugar called glucose which is carried in the blood, raising blood sugar levels. The hormone insulin acts as a key within the gates of the cells to allow glucose to enter.

The problem with the modern diet

The problem is, fat and carbohydrate metabolism are mutually exclusive. Carbs, being rare for millions of years of history, are preferentially used by the human body. As modern people, we live in a state of constant harvest. Our bodies react to carbohydrates with the aim to store, insulin is released to shuttle them into our cells.

If you look at the standard American diet, almost every meal contains carbohydrates. From the bagel at breakfast, to the sandwich at lunch, to the steak and potatoes for dinner, we constantly eat carbohydrates. This makes us less able to use fat as a fuel source. Switching into ketosis takes over a week for most people, and until then the fat on the body cannot be used for fuel.

If you turn off the faucet for carbs, you are in big trouble from an energy perspective. How do you prevent this, and how can you prepare yourself from being separated from food? More in the next post in this series.