Why We Need Food
The food we eat the essential building blocks of life. Good and bad building blocks. All foods contain two main categories of nutrients, the macronutrients and the micronutrients.
Macronutrients: required in large amounts for healthy growth and development, they form the basis of every diet and they provide energy for all the body’s everyday functions and activities. Macronutrients are categorized as being primarily fats, proteins and carbohydrates.
Micronutrients: These are made up of vitamins and minerals. They are called micronutrients because they are found in tiny amounts in our food. Unlike micronutrients, vitamins and minerals do not provide energy and are needed in small amounts, but they play a critical role in the normal functioning of the body and digestive processes, to ensure good health.
The Energy Yield Of Food: In addition to supplying the body with nutrients, food also provides the body with energy. Approximately half to two thirds of the energy we obtain from food goes to support the body’s basic, involuntary functions, which are the activities that are performed without any conscious control, such as heart rate, maintaining breathing, and body temperature.
The minimum energy needed to carry out these functions is determined by your basal (base) metabolic rate (BMR), which is your baseline rate of metabolism, measured when the body is at rest.
You also expend energy through conscious, voluntary activities, which range from the sedentary to the strenuous. All your body’s energy needs are met from the foods that you eat or from your body’s energy stores.
Calculating Your Energy Requirements: Your energy requirements depend on various factors, including age, gender, physical activity, muscle mass, body temperature, and whether you are still growing.
Pregnancy, illness, infection, how much you eat or sleep, and hormone levels are additional factors. As discussed earlier, basal metabolic rate (BMR) is a measure of how much energy you need for essential functions such as breathing and heart rate.
BMR is measured by taking into account a person lean weight, which is your total weight minus your fat weight. BMR is highest in the young and starts to decrease after the age of ten. Because of their greater capacity to increase muscle mass, men generally have a higher BMR than women.
Due to a declining muscle mass, as we grow older, we generally have a lower BMR and require less consumption of calories.
Example of the calorie requirements for different people and activity level-
Sedentary and bed bound people: 11.5 cal per 1b of body weight per day
People who do light activities: 13.5 cal per 1lb of body weight per day
People doing moderate activities and a regular exercise programme: 16 cal per 1lb of body weight per day
Those doing vigorous exercise and work, also patients recovering from injury: 18 cal per 1lb of body weight per day