Basal Metabolic Rate (BMR)

Simple, fast and easy

Total Daily Energy Expenditure (TDEE)

Simple, fast and easy

Basal Metabolic Rate (BMR)

The Basal Metabolic Rate (BMR) represents the minimum amount of energy that the body needs to maintain vital functions at rest, such as breathing, blood circulation, and temperature control.

What is BMR for?

  • Estimation of daily energy needs.
  • Basis for nutritional calculations and diet planning.
  • Fundamental for adjusting diets for weight maintenance, loss, or gain.

How does the calculation work?

The BMR calculation takes into account factors such as sex, age, weight, and height. The main formulas used are:

1. Harris-Benedict Formula (1919)

This formula is one of the most traditional for estimating BMR:

For men:

$$ \text{TMB} = 88.362 + (13.397 \times \text{peso [kg]}) + (4.799 \times \text{altura [cm]}) - (5.677 \times \text{idade [anos]}) $$

For women:

$$ \text{TMB} = 447.593 + (9.247 \times \text{peso [kg]}) + (3.098 \times \text{altura [cm]}) - (4.330 \times \text{idade [anos]}) $$

2. Mifflin-St Jeor Formula (1990)

Currently considered one of the most accurate for adults:

For men:

$$ \text{TMB} = (10 \times \text{peso [kg]}) + (6.25 \times \text{altura [cm]}) - (5 \times \text{idade [anos]}) + 5 $$

For women:

$$ \text{TMB} = (10 \times \text{peso [kg]}) + (6.25 \times \text{altura [cm]}) - (5 \times \text{idade [anos]}) - 161 $$

3. Schofield Formula (1985) - WHO

Recommended by the World Health Organization (WHO), especially for pediatric and elderly populations, with distinct age ranges:

For men:

  • 0-3 years: BMR = 60.9 × weight - 54
  • 3-10 years: BMR = 22.7 × weight + 495
  • 10-18 years: BMR = 17.686 × weight + 658.2
  • 18-30 years: BMR = 15.057 × weight + 692.2
  • 30-61 years: BMR = 11.472 × weight + 873.1
  • Above 61 years: BMR = 11.711 × weight + 587.7

For women:

  • 0-3 years: BMR = 61.0 × weight - 51
  • 3-10 years: BMR = 22.5 × weight + 499
  • 10-18 years: BMR = 13.384 × weight + 692.6
  • 18-30 years: BMR = 14.818 × weight + 486.6
  • 30-61 years: BMR = 8.126 × weight + 845.6
  • Above 61 years: BMR = 9.082 × weight + 658.5

Fun Facts

  • BMR accounts for about 60-75% of the total daily caloric expenditure in sedentary people.
  • Muscle is metabolically more active than fat, so people with more muscle mass tend to have a higher BMR.
  • Factors such as ambient temperature, health status, hormones, and genetics also influence BMR.

Important

Although formulas are useful for estimating BMR, they do not replace clinical and metabolic assessments performed by health professionals.

Total Daily Energy Expenditure (TDEE)

Total Daily Energy Expenditure, known as TDEE, represents the total amount of calories a person burns in a day, including the calories needed to maintain vital functions, perform physical activities, and digest food.

What is TDEE for?

Knowing TDEE is fundamental for planning diets and workouts, as it indicates the total energy consumed and allows adjusting caloric intake for weight loss, gain, or maintenance.

How does TDEE calculation work?

TDEE is calculated by multiplying the Basal Metabolic Rate (BMR) by the person's physical activity level. BMR represents the energy expenditure to maintain the body's basic functions at rest.

The general formula is:

$$ \text{TDEE} = \text{TMB} \times \text{Fator de Atividade} $$

Methods for TDEE calculation

There are two main methods for defining the activity factor:

Standard Method

Uses factors based on the intensity of daily activities:

  • Sedentary: 1.2
  • Lightly active: 1.375
  • Moderately active: 1.55
  • Very active: 1.725
  • Extremely active: 1.9

WHO (World Health Organization) Method

The WHO recommends slightly larger factors to more accurately represent different levels of physical activity:

  • Sedentary: 1.4
  • Lightly active: 1.6
  • Moderately active: 1.8
  • Very active: 2.0
  • Extremely active: 2.4

Thus, using the WHO method, the formula becomes:

$$ \text{TDEE}_{\mathrm{OMS}} = \text{TMB} \times \mathrm{NAF} $$

Practical example

If a person has a BMR of 1500 kcal and is moderately active, their TDEE can be calculated as:

  • Using the standard method: \( 1500 \times 1.55 = 2325 \) kcal/day
  • Using the WHO method: \( 1500 \times 1.8 = 2700 \) kcal/day

Fun Facts

  • TDEE varies according to age, sex, body composition, and physical activity level.
  • Individuals with more muscle mass generally have a higher TDEE.
  • Frequent and intense physical activities significantly increase TDEE.

Importance of TDEE in Nutrition

Understanding TDEE helps control energy balance: consuming more calories than TDEE promotes weight gain, while consuming less promotes loss.

Adjusting calories based on TDEE is the foundation for effective and sustainable diets.

Final considerations

The TDEE calculation is an estimate that should be used as a guide. For personalized nutritional plans, consultation with professionals is recommended.