The Schofield Equation is a widely used method for estimating the basal metabolic rate (BMR) of adult men and women. Published in 1985, this equation provides a standardized approach to calculating daily calorie needs based on body mass and age. It has been adopted by organizations such as the World Health Organization (WHO) to help determine energy requirements for individuals.
How the Schofield Equation Works
The Schofield Equation estimates BMR in kilojoules per day (kJ/day) or
kilocalories per day (kcal/day) using body mass in kilograms. Separate equations are provided for men and women, with adjustments based on age groups. For example, the equation for men aged 18-30 is 63 times body weight plus 2896, while for women in the same age group, it is 62 times body weight plus 2036.
These equations take into account the standard error of estimation (SEE), which provides a confidence limit for the calculated BMR. Adjustments are recommended for individuals who are leaner, more muscular, or obese, as these factors can affect energy requirements. The Schofield Equation serves as a baseline for calculating total energy expenditure (TEE) by incorporating physical activity levels.
Physical Activity Levels and Total Energy Expenditure
To determine total energy expenditure, the base metabolism calculated by the Schofield Equation is multiplied by a physical activity level factor. These factors range from sedentary to extremely active, reflecting the individual's daily routine and exercise habits. For instance, a sedentary lifestyle has a factor of 1.3, while an extremely active lifestyle has a factor of 2.4 for men and 2.2 for women.
The Schofield Equation has been used in dietary guidelines and recommended daily allowances (RDAs) for years. While it has been replaced by newer equations in some regions, it remains a valuable tool for estimating energy needs, particularly in conjunction with physical activity levels.
Limitations and Current Use
Despite its widespread use, the Schofield Equation has limitations. It does not account for body composition, which can lead to inaccuracies in estimating energy needs for individuals with varying muscle and fat proportions. Additionally, the equation may not be applicable to those outside the 'normal' and 'overweight' body mass index categories.
In the U.S., the equation has been replaced by the Institute of Medicine Equation, but it continues to be used by the FAO/WHO/UNU. Understanding the Schofield Equation and its application can help individuals and healthcare professionals better assess energy requirements and tailor dietary plans accordingly.
