Human body energy requirement

Posted on do 02 juni 2022 in blog

Recently I got asked about about creating a garden with the specific aim of keeping starvation at bay. I came to the conclusion you need crops that contain at least sufficient calories to keep you going. So starchy, sugary, oily or protein rich.

Check out the table on the Potato wikipedia page comparing the different staple foods around the world. And seeing how much energy an average adult needs: a sedentary male (like myself) needs about 11000kJ per day!

Note that the human body needs more than just calories. It needs to replenish building blocks so a reliable source of protein is also vital. Think of beans, eggs, cheese or other milk products and meat.

Looking at the energy content of sunflower oil (3700kJ/100g), I can sustain on about 300g of oil per day.

Looking at the energy content of potato (1500kJ/100g dry weight, about 500g of raw potato per 100g of dry weight), I need to eat at least 3,5kg of potato per day. Note that of all the staples mentioned, only the potato contains all the nutrients your body needs in one neat package.

For white rice I need to eat at least 700g per day. (11000kJ/d ÷ 1700kJ/dry × 114 wet/dry).

Multiply everything by about 400 to get what you need per year: 120kg of oil, OR 1400kg potatoes OR 280kg white rice. That is: using ONLY that food source.

Combining the three (taking 1/3 of each), I need 40kg of oil AND about 500kg of potatoes AND about 100kg of rice PER YEAR.

As an aside, ethanol has an energy content of 2680kJ/100g. At 40% proof that reduces to 1072kJ/100g (2680kJ/100g × 0.4). I need to drink 1026g per day (11000kJ/d ÷ 1072kJ/100g) to get sufficient calories. Eat whipped cream for additional oil and protein.