Schofield equation

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The Schofield Equation is a method of estimating the basal metabolic rate (BMR) of adult men and women.[1]

This is the equation used by the WHO in their technical report series.[2] The equation that is recommended to estimate BMR by the US Academy of Nutrition and Dietetics is the Mifflin-St. Jeor equation.[3]

The equations for estimating BMR in kJ/day (kilojoules per day) from body mass (kg) are:[4]

Men:

Age Equation (kJ/day) SEE
< 3 249 × W - 127 292
3–10 95 × W + 2110 280
10–18 74 × W + 2754 441
18–30 63 × W + 2896 641
30–60 48 × W + 3653 700
> 60 49 × W + 2459 686

Women:

Age Equation (kJ/day) SEE
< 3 244 × W - 130 246
3–10 85 × W + 2033 292
10–18 56 × W + 2898 466
18–30 62 × W + 2036 497
30–60 34 × W + 3538 465
> 60 38 × W + 2755 451

The equations for estimating BMR in kcal/day (kilocalories per day) from body mass (kg) are:

Men:

Age Equation (kcal/day) SEE
< 3 59.512 × W - 30.4 70
3–10 22.706 × W + 504.3 67
10–18 17.686 × W + 658.2 105
18–30 15.057 × W + 692.2 153
30–60 11.472 × W + 873.1 167
> 60 11.711 × W + 587.7 164

Women:

Age Equation (kcal/day) SEE
< 3 58.317 × W - 31.1 59
3–10 20.315 × W + 485.9 70
10–18 13.384 × W + 692.6 111
18–30 14.818 × W + 486.6 119
30–60 8.126 × W + 845.6 111
> 60 9.082 × W + 658.5 108

Key:

W = Body weight in kilograms

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 energy than the average. Obese subjects require less. Patients at the young end of the age range for a given equation require more energy. Patients at the high end of the age range for a given equation require less energy.

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 energy needed per day (Estimated Energy Requirement), 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 in the USA, however is still currently used by the FAO/WHO/UNU.

References[edit]

  1. ^ Schofield WN (1985). "Predicting basal metabolic rate, new standards and review of previous work". Hum Nutr Clin Nutr. 39 Suppl 1: 5–41. PMID 4044297. 
  2. ^ World Health Organisation, Fao, and Unu. Energy and protein requirements. Geneva: WHO, Technical Report Series 724, 1985.
  3. ^ J Am Diet Assoc. 2009;109:330-346.
  4. ^ Energy Requirements of Adults, Report of a Joint FAO/WHO/UNU Expert Consultation, (See table 5.2).