What exactly does a calorie know?
The calorie (also defined as a unit of energy equivalent to 4.18 joules) is used as a measure to express energy consumption, energy expenditure (MB) and physical activity. More precisely, one calorie refers to the quantity needed to raise the temperature of one kilogram of water by 1 degree Celsius. So, to determine the calorie content of a food, we estimate the amount of heat required to burn it. Daily energy intake depends on a number of factors, such as age, size, metabolic requirements, daily activities, and so on. The approximate number of calories required daily for different age groups is 1100 calories in infancy; 1500-1800 calories in childhood; 2200-3000 in adolescence; 4500 calories for athletes and 2000-2300 calories for seniors.
It should be pointed out that daily intake ratios (consumed/expended) depend on a number of factors, such as metabolic requirements, lean/fat mass ratio, general health status, type of work and type of shift (day or night), duration of activity, and so on. On this basis, it is impossible to clearly indicate what the daily intake ratios are. However, the ratio of 45-55 % of carbohydrates, 15-30 % of proteins and 25-35 % of lipids reflects the typical needs of North Americans and Europeans.
The 3 “Caloric” nutrient categories”
There are three categories of energy-providing nutrients: carbohydrates, proteins and fats. Each gram of carbohydrate and protein provides four calories, while one gram of fat provides nine calories. The ratios of energy expenditure (calories) are distributed as follows: 60-70 % for vital functions (body temperature, cardiovascular and cardiorespiratory metabolism, secretion from glands, normal muscle tone and tension, neurological activities); 20-30 % for physical activities (sport, activities, work, leisure); 10 % for digestion and absorption of food.
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