Schofield equation

The Schofield Equation is a method of estimating the basal metabolic rate (BMR) in calories of adult men and women.

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It is commonly used by dieticians as a means of estimating the total calorie intake required to maintain current body mass. This figure can then be used to design a dietary regime that places the subject in calorie deficit or surplus, depending on whether weight loss or gain is the intended clinical outcome.

Men:

10 - 17 years BMR = 17.7 x W + 657 SEE = 105

18 - 29 years BMR = 15.1 x W + 692 SEE = 156

30 - 59 years BMR = 11.5 x W + 873 SEE = 167

Women:

10 - 17 years BMR = 13.4 x W + 692 SEE = 112

18 - 29 years BMR = 14.8 x W + 487 SEE = 120

30 - 59 years BMR = 8.3 x W + 846 SEE = 112

Key: W = Body weight in Kilograms - convert body weight here!

SEE = Standard error of estimation

The raw figure obtained by the equation should be adjusted up or downwards, within the confidence limit suggested by the quoted estimation errors, and according to the following principles:

Subjects leaner and more muscular than usual require more calories than the average. Obese subjects require less. Patients at the young end of the age range for a given equation require more calories. Patients at the high end of the age range a given equation require more calories.

Effects of age and body mass may cancel out: an obese 30 year old or an athletic 60 year old may need no adjustment from the raw figure.

To find actual calorie need, the base metabolism must then be multiplied by an activity factor. These are as follows:

• Sedentary people of both genders should multiply by 1.3. Sedentary is very physically inactive, inactive in both work and leisure.

• Lightly active men should multiply by 1.6 and women by 1.5. Lightly active means the daily routine includes some walking, or intense exercise once or twice per week. Most students are in this category.

• Moderately active men should multiply by 1.7 and women by 1.6. Moderately active means intense exercise lasting 20-45 minutes at least three time per week, or a job with a lot of walking, or a moderate intensity job.

• Very Active men should multiply by 2.1 and women by 1.9. Very active means intense exercise lasting at least an hour per day, or a heavy physical job, such as a mail carrier or an athlete in training.

• Extremely active men should multiply by 2.4 and women by 2.2. Extremely active means an athlete on an unstoppable training schedule or a very demanding job, such as working in the armed forces or shoveling coal.

These equations were published in 1989 in the dietary guidelines and formed the RDA's for a number of years. The activity factor used by the USDA was 1.6. In the UK, a lower activity factor of 1.4 is used. The equation has now been replaced by the Institute of Medicine Equation in September 2002.