Your body works on energy extracted from the food, which contains calories. The digestive system absorbs essential nutrients and converts them into energy as and when a physical activity takes place. In absence of physical exercise, the calories are retained in the body.
There is a proportionate requirement for how much calories of food are to be consumed in a day. The body can gain or lose weight if there is a non-proportionate intake of calories. Every food has its own calorific potential i.e. a food can be high calorie or a low calorie food. More calories will lead to overweight and vice-versa.
We can calculate the calorific value of food based on three inherent factors i.e. Degree of physical work, Basal Metabolic rate and thermal effect of food.
Basal Metabolic Rate (BMR):
BMR is the equivalent energy required by body in stable condition i.e. without any significant activity. Pumping operation by heart, breathing operation, blinking and maintaining constant body temperature are major calorie consuming activities in stable condition.
60-70 %of the calories burn inside body in a day are used to support these basic body functions. Harris-Benedict discovered the empirical formula of calculating BMR.
For Adult Male
BMR = 66 + (13.7 x W) + (5 x H) – (6.8 x age)
Adult Female – 655 + (9.6 x W) + (1.8 x H) – (4.7 x age)
W= weight in kilos
H = height in cm.
Therefore, if a 35 year old person weighs 60 kg and is 167 cm tall.
BMR required= 66 + (13.7 × 60) + (5 × 167) – (6.8 × 35) = 1961 Kcal.
Another major consumption agent of calories is the degree of physical activity a person has to do. More the physical activities, the more your calorie requirements will be.
Even a small activity like neck movement, waking up, changing your sitting position can consume calories. Calculations based on activities of the human body are explained here:
Calories in stationary position (small movements) = BMR x 1.2
Low exercise, say 3 days a week= BMR x 1.375
Routines involving Movements 5 days a week =BMR x 1.55 (average)
Active exercise or sports in whole week= BMR x 1.725
Hard work or physical exercise involving training etc. = BMR x 1.9
Calorific Effects of food:
The degree of calories required by your body in order to digest the food you consumed. Mathematically, the calories you eat should be multiplied by 0.1 i.e. 10% of the total calories consumed.
Calorific Effect of Food = Total kcals consumed x 10% (0.10)
The cumulative summation gives you the energy required by your body for the activities that you undertake.
The most important advantage of determining the calories is that you may plan your amount of work and the calories that you consume by means of food. A proper balanced diet will maintain your weight as well as your physical health.