# Calculation of BMR and energy requirement

Calculate basal metabolic rate (BMR) and energy requirements to get total daily calories. Use the BMR calculator (Mifflin and St Jeor.) – an expanded version of the Harris Benedict equation.

*The results obtained are approximate and depend on individual cases and additional factors.

## Calculate BMR by Harris Benedict equation

BMR – basic metabolic rate shows us how much energy we need during the day (24 hours) for the body to work. No physical exertion is included here, only metabolism. Therefore, the obtained value should be multiplied by the coefficient of physical activity.

Calculating your BMR is therefore the basis for setting a calorie diet for the whole day. Knowing our daily calorie requirements, we can control our weight. You can establish a diet that will contain fewer calories to lose weight or more calories to gain weight.

The BMR index is also known as the Harris-Benedict equation. The original equation was created at the beginning of the 20th century. Since then, the tn formula has undergone several modifications to better reflect the actual caloric values.

**A modern version of the Harris Benedict equation developed in 1990 by Mifflin and St Jeor.:**

Sex | Calculation in metric units |

Men | BMR = (10 × weight [kg]) + (6.25 × height [cm]) – (5 × age [years]) + 5 |

Women | BMR = (10 × weight in [kg]) + (6.25 × height [cm]) – (5 × age [years]) – 161 |

Sex | Calculation in imperial units |

Men | BMR = (4.536 × weight [pounds]) + (15.88 × height [inches]) – (5 × age [years]) + 5 |

Women | BMR = (4.536 × weight [pounds]) + (15.88 × height [inches]) – (5 × age [years]) – 161 |

## Determining the level of physical activity (PAL)

The physical activity level (PAL) allows you to easily determine the limits of our additional energy demand. PAL is used together with BMR according to the formula Total caloric requirement = BMR x PAL. It is worth adding that PAL does not reflect the real values for pregnant women.

Level of effort and examples | PAL | Mean |

Extremely low – bed rest, restricted mobility | >1.40 | |

Low – sitting at the computer | 1.40-1.69 | 1.55 |

Average – manual worker or practicing sports every day | 1.70-1.99 | 1.85 |

High – hard physical work or exercise min. 2 hours a day | 2.00-2.40 | 2.2 |

Extremely high – professional sports | >2.40 |

## Total energy requirement

The conducted analysis shows that the total caloric intake during the day depends on age, sex, weight, height and activity during the day. Knowing all these values, you can use a BMR calculator and multiply the obtained value by PAL to get the total demand.

Comparing two identical people who differ only in physical activity during the day, it can be concluded that high physical effort causes almost twice as many calories. It is worth mentioning that our energy demand will decrease with age.