Calories Part 1 - Basics

There is a unit of energy called "calorie" which is equal to enough heat energy needed to raise temperature of 1 gram of water 1 degree centigrade. In diet calculations a higher unit of energy "Calorie" (with capital C) is used which is equal to 1000 calories, enough heat energy to raise temperature of 1 kg water 1 degree centigrade.

In diet requirements, an organism needs 30 to 50 Calories per kg body mass. This is true for all animals and humans. A person doing light work such as table work needs just 30 Calories whereas a farmer or a carpenter needs 50 Calories. For our calculations we take the average 50 Calories.

Other than noting the overall energy need its also important to know the components of food needed. There are seven components of food: Carbohydrates, Proteins, Fats, Minerals, Vitamins, Fiber and Water. The last two, Fiber and Water, contains no energy at all, fiber is needed to rest the system as system not have to digest the fiber, water is needed to keep the digestive system clean. Minerals and Vitamins also contains no energy but are needed to rebuild the body after daily wear and tear. The only energy contents are first three, in this article we discuss only them.

Each gram of Carbohydrate contains 4 Calories, each gram of Protein also 4 Calories, each gram of Fats 9.2 Calories. For a balanced diet, 56-60 percent of energy must come from Carbohydrates, 12-15 percent from Proteins and the rest 25-32 percent from Fats.

The amount of diet energy needed depends of level of activity which is constant for a given person. A farmer remains to be a farmer and a clerk clerk. The other thing energy depends on is body mass which in turn depends on height which in turn depends on age if the body is growing.

Lets take the simple case of an adult who have reached the maximum height it would acquire in his/her lifetime. This adult would have in most cases also fixed its activity level by choosing a profession and gain enough mass appropriate to height. In most cases the optimum mass of 5'8" to 6' man is 75 kg and a naturally shorter woman of equal age 62.5 kg. For the population as a whole the average ideal mass is 50 kg, that is, if you consider children too.

Lets take 50 kg average mass and average activity level, that translates into a 2000 Calories daily energy need. Note that even for a 75 kg adult mass if doing office work the energy requirement is close to 2000 Calories, actually 2250 Calories. For a 2000 Calories, 1200 Calories must come from Carbohydrates (60%) which means 300 grams of it and 300 Calories from Proteins (15%) which means 75 grams and 500 Calories from Fats (25%) which means 55 grams.

So, in short, for an average person, the need is 300 grams Carbohydrates, 75 grams Proteins and 55 grams Fats. Each of these components of food available in different food items is given below in percentages:

ITEM      CH       P      F     Calories

Honey    80.00     -      -       3.20
Milk      4.88    3.32   3.64     0.66
Wheat    66.67   12.10   2.70     3.40
Rice     70.00   10.00   4.35     3.60
Millet   23.68    3.51   0.98     1.18
Barley   73.48   12.50   2.28     3.65
Pulses   50.00   26.00   6.00     3.60
Fruits*  12.50     -      -       0.50
Others   25.00     -      -       1.00
Veg       6.25     -      -       0.25
Mutton     -     26.00   0.87     1.12
Beef       -     80.00    -       3.20
Fish       -     18.00    -       0.72
Butter     -       -    80.00     7.29
Sugar   100.00     -      -       4.00
Oil        -       -   100.00     9.20
Spices   50.00   20.00    -       2.80

*This is an average calculation for different types of fruits not including those having a higher sugar amount such as banana/mango etc

Another thing to consider in getting the food is how much load it put on soil, in short how much land is needed to support an average person.