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Q: What is the total nutritional value (calories, fat, vitamins, minerals, etc.) of the average human body?
Randall’s response: Black Hat Guy [a character who plays evil pranks] says, “…I need to know by Friday. Shhh! Here he comes.”
My response: Please note that Science Meets Fiction does not condone cannibalism.
This is a surprisingly complex question that involves a lot of points of nutrition, biochemistry, and even demographics, and I’m going to need multiple posts to fully answer it. It’s fairly difficult to figure out the average chemical content of the human body. You can find a basic breakdown pretty easily, but nutritional information is more complicated. Let’s look at some of the parts involved.
In this post, I will start by calculating the serving size and calorie content of the human body.
The Average Human Body
Obviously, there’s a big different between male and female bodies, but this is also going to vary by country. Richer countries where childhood nutrition is better will produce taller and heavier people than poorer countries, and even at the same level of development, there will be differences. The average man in Bahrain, a very rich country, is 5 feet 5 inches tall, while the average man in Mali, a much poorer country, is 5 feet 7.5 inches. Worldwide, though, the average height is 5 feet 8 inches for men and 5 feet 3 inches for women.
But we don’t need height. We need weight. In the West, the average person is significantly overweight, while in very impoverished areas, the average person is probably underweight, but since most of the world is in the middle (for more on that, look here), let’s assume that the average human is a healthy weight, which for the average height, works out to 154 pounds for men and 115 pounds for women. Since half of the population is male and half is female, the average weight of a human body is 135 pounds (61 kilograms).
Serving sizes are calculated somewhat arbitrarily by the US Department of Agriculture, taking into account how much of a particular food people eat in a meal and how much they should eat. This can sometimes result in unrealistic serving sizes, such as a standard serving of ice cream being 1/2 cup, about half of what people typically eat.
Now, humans are vertebrate animals, and here in America, when people eat vertebrate animals, we usually only eat the muscle, i.e., meat. However, just about every part of an animal is edible, including organs, blood, bones (a dietary supplement), and BRAINS! (although you’ll want to be careful about that last one). The question asked for the total nutritional value of the human body, so we’ll include all of it.
So what is the serving size for human. The different parts will have different serving sizes, but the dry weight of the human body is about 44% protein, 36% fats, 4% carbs, and 16% minerals. (This is again an average between males and females, who have a different body fat content.) Most of this bulk is equivalent to some pretty fatty meat, so we’ll use that for the serving size: 3 ounces (85 grams) of cooked meat.
The human body is about 65% water, but cooking removes some of this water. Cooked fatty meat is about 55% water, so our 135 pound human body is reduced down to 105 pounds (48 kilograms), for a total of 560 servings.
Calories per Serving
This one is pretty easy. Fats contain 8.8 kilocalories (or food calories) of energy per gram, while proteins and carbs are about the same at 4.1 calories per gram. Minerals don’t contain calories. So our 85 gram serving of human contains about
440 calories. Correction: 200 calories. I hadn’t accounted for the water content.
Oh, and you’re probably going to want some fiber on the side.
In Part 2, I discuss the actual nutrient breakdown of the human body.