1 kcal = 4.2 kJ

Daily energy intake depends on body type and lifestyle factors. Lifestyle factors include activity levels and exercise. It is calculated by multiplying your basal metabolic rate and physical activity level.

Basal metabolic rate (BMR) is the amount of energy used for the maintenance of basic life processes in 24 hours by a person fasting for at least 12 hours and who is physically and mentally at rest, at room temperature (18-24 ° C).

For adults, the basal metabolism is calculated by using Harris-Benedict predictive equations (with a coefficient of variation of approximately 8 %):
  • BMRman = 66 + (13.7 * weight in kg) + (5 * height in cm) - (6.8 * age in years),
  • BMRwoman = 655 + (9.6 * weight in kg) + (1.8 * height in cm) - (4.7 * age in years).
During pregnancy, the need for energy increases by about 255 kcal/day. Womenwho bear more than one child need extra calories; to provide additional amounts of blood and because of the size of the uterus and the development of two or more embryos, there are also additional needs for essential fatty acids, calcium and iron. Nursing mothers during the first four months after birth are recommended an additional energy intake of 635 kcal/day. After the fourth month after birth, the extra energy intake depends on whether a mother breastfeeds fully or partially. In case of full breastfeeding additional 525 kcal/day are necessary, otherwise additional 285 kcal/day are enough.

With fever, the need for the amount of energy for basal metabolism is increased by 7 % per each degree Celsius increased.

Daily Activity Level (Physical Activity Level – PAL)  has a significant impact on the energy needs. 
Physical activity levels

Physical activity level
Women Men Description
very low 1.00-1.29 1.00-1.29 mainly sitting and lying (old, decrepit people)
low 1.30-1.49 1.30-1.59 exclusively sedentary activity with little or no strenuous leisure activities (clerks, precision mechanics)
moderate 1.50-1.59 1.60-1.69 sedentary activity and occasionally higher energy consumption for walking and standing activity (laboratory assistants, drivers, students, workers on an assembly line)
high 1.70-1.89 1.90-2.09 mostly standing work (housewives, salesmen, waiters, mechanics, craftsmen)
very high 1.90-2.20 2.10-2.40 physically strenuous professional work (construction workers, farmers, loggers, miners, competitive athletes)

To reduce the risk of obesity, cancer and heart attacks in adults, it appears that the activity level should be at least 1.75. Moderate activity has a good effect on blood pressure and blood fat content, and also regulates blood sugar levels. Regular exercise increases our muscle mass which is a major energy consumer.

We recommend you to choose your daily physical activity levels considering your professional work. Occasional physical activities, such as housework, playing with children, care for the elderly, recreation, etc. can be kept track of in the food diary or menu.

It should be mentioned that children and adolescents from 1-18 years old spend about
  • 50 % of energy for basal metabolism,
  • 12 % of energy for growth,
  • 25 % for physical activity and
  • 13 % for other needs.
The application considers the recommended daily energy intake for children and adolescents acoording to their age group and gender. Normal weight, height and age-adjusted moderate physical activity is also considered here.

Daily energy intake for children and adolescents

Age (years) Recommended daily energy intake
kJ (kcal)/day
young/older boys young/older girls
1-3 5150 (1250) 4800 (1150)
4-6 6700 (1600) 6150 (1450)
7-9 8300 (2000) 7500 (1800)
10-12 10150 (2450) 9000 (2150)
13-14 11700 (2800) 10050 (2400)
15-18 13000 (3100) 10500 (2500)


Daily energy needs of unhealthy individuals can be calculated as follows:
  • active patients: 30-35 kcal/kg body weight/day;
  • lying patients: 20-25 kcal/kg body weight/day.
This estimate is less reliable in very light patients (energy consumption per kilogram of body weight is greater in this group) and in heavy patients (BMI above 30), where the consumption is calculated with regard to the ideal body weight + 25 %.

Total daily energy intake should be distributed per meals according to the these guidelines:
  • breakfast: 18 - 22 % of the total daily energy intake;
  • morning snack: 10 - 15 % of the total daily energy intake;
  • lunch: 35 - 40 % of the total daily energy intake;
  • afternoon snack: 10 - 15 % of the total daily energy intake;
  • dinner: 15 - 20 % of the total daily energy intake.
It is important to eat several times a day, especially for children, because their energy storage capacity is smaller than in adults. A child's working capacity during the day can be much influenced by the food, particularly by the proper distribution of meals.

porazdelitev energije po obrokih

Every individual or their trustee can choose their own distribution of the total daily energy intake with meals which is considered in both, the food diaries as well as the menus.