11-08-2012, 10:52 AM
(This post was last modified: 11-08-2012, 10:57 AM by Tenet Nosce.)
It would be very difficult to have any conversation about diet with discussing nutrient density. That is to say: How much of a given nutrient occurs per unit of food.
But I have noticed that much confusion has appeared due to the conflating of three different units of measurement of food: grams, cups, and calories.
The gram is a unit of mass. This is what is reported when we place something on a scale. In the U.S., we might also discuss ounces or pounds. These are all units of mass.
The cup is a unit of volume. This refers to how much physical space something occupies.
For example, a kilogram of spinach has much more volume than a kilogram of almonds. But they have the same mass.
On the other hand, a cup of almonds has much more mass than a cup of spinach. Yet, they have the same volume.
The calorie is a unit of energy. This refers to how much heat would be released if the food were to be combusted, or burned.
Now let's look at a real-life example using almonds and spinach.
Which has more protein, almonds or spinach? The answer depends on which units you are using.
A cup of almonds has a total mass of 138 grams, and contains 824 calories of energy.
In the cup of almonds is about 30 grams, or 120 calories of protein.
That means, almonds are 21.7% protein by mass and 14.6% protein by energy content.
A cup of spinach has a total mass of 30 grams, and contains 7 calories of energy.
In the cup of spinach is about 1 gram, or 4 calories of protein.
That means, spinach is 3.3% protein by mass and 57.1% protein by energy content.
The human body requires somewhere around 2000 calories of energy from food a day. It also requires somewhere around 60 grams of protein. That means our diet should be somewhere around 12% protein, by calorie.
That means, if we were going to get all of our protein from almonds we would need to eat 2 cups of almonds in a day.
In contrast, if we were going to get all of our protein from spinach we would need to eat 60 cups of spinach in a day.
Something to keep in mind when reading books or watching viral videos on diet. Many "gurus" appear to be confused about these different units.
But I have noticed that much confusion has appeared due to the conflating of three different units of measurement of food: grams, cups, and calories.
The gram is a unit of mass. This is what is reported when we place something on a scale. In the U.S., we might also discuss ounces or pounds. These are all units of mass.
The cup is a unit of volume. This refers to how much physical space something occupies.
For example, a kilogram of spinach has much more volume than a kilogram of almonds. But they have the same mass.
On the other hand, a cup of almonds has much more mass than a cup of spinach. Yet, they have the same volume.
The calorie is a unit of energy. This refers to how much heat would be released if the food were to be combusted, or burned.
Now let's look at a real-life example using almonds and spinach.
Which has more protein, almonds or spinach? The answer depends on which units you are using.
A cup of almonds has a total mass of 138 grams, and contains 824 calories of energy.
In the cup of almonds is about 30 grams, or 120 calories of protein.
That means, almonds are 21.7% protein by mass and 14.6% protein by energy content.
A cup of spinach has a total mass of 30 grams, and contains 7 calories of energy.
In the cup of spinach is about 1 gram, or 4 calories of protein.
That means, spinach is 3.3% protein by mass and 57.1% protein by energy content.
The human body requires somewhere around 2000 calories of energy from food a day. It also requires somewhere around 60 grams of protein. That means our diet should be somewhere around 12% protein, by calorie.
That means, if we were going to get all of our protein from almonds we would need to eat 2 cups of almonds in a day.
In contrast, if we were going to get all of our protein from spinach we would need to eat 60 cups of spinach in a day.
Something to keep in mind when reading books or watching viral videos on diet. Many "gurus" appear to be confused about these different units.