8. SUMMARY OF REQUIREMENTS FOR ENERGY AND PROTEIN

8.1 Introduction

The aim of this section is to summarize the estimates derived in section 6, on the principles discussed in sections 4 and 5. The derivation of corrections to be applied for different diets is described in section 7.

8.1.1 Precision of estimates

The calculations in section 6 have been made with a greater degree of precision, or apparent precision, than can ever be useful in practice. In this section the figures are rounded off, usually to 2 digits only.

8.1.2 Age ranges

The age ranges used for adults are those discussed in section 3.5. For children, somewhat narrower ranges have been adopted. Even so, they embrace a very wide span of body weights. For example, for boys 3–5 years old, the acceptable range of body weight extends from 12 kg (3 years, 5th centile) to 23 kg (5 years, 95th centile). Therefore, if greater precision is needed, the more detailed tables in section 6 should be consulted.

8.1.3 Relation to body weight

Both energy and protein requirements are related to body weight, although in a different way. The estimates given in the following tables relate only to subjects whose weight is within the acceptable range for height (adults) or age (children). The approach to be adopted for those outside these ranges is discussed in section 9. It has been emphasized (section 3.5) that within the acceptable ranges, the estimates of requirements may be based either on the actual weight, or on the median weight for height or age (“normative” estimates, see section 3.5.1), according to the objectives for which they are to be used.

It should be stressed, however, that for children, in whom the range of body weight within acceptable limits for age (10th–90th centiles) is very wide, the normative approach will under - or overestimate the requirements of those at the extremes of the distribution.

8.1.4 Corrections for characteristics of the diet

For both energy and protein a correction may have to be made for digestibility, and in the case of protein, for quality also (section 7). In contrast to previous practice, it is recommended that when comparisons are being made between requirements and dietary intakes, the corrections should be applied to the diet rather than to the values for requirements. The reason for this is that it will facilitate aggregated comparisons between intakes and requirements, for example for a family unit, when different members of the family consume different diets (see section 11.4). However, there are situations in which the user may find it more convenient to make the correction in the traditional way, i.e., by adjusting the estimate of requirement.

The method of making these corrections is summarized in Table 51.

8.2 Adults

The energy and protein requirements of adult men and women in three age ranges are shown in Tables 42–47.

8.2.1 Energy

The energy requirement is determined in these tables from the body weight and the level of physical activity, as defined by the BMR factor. Values of the BMR factor appropriate for different general levels of physical activity have been given in Table 15, and some examples have been shown in Tables 9–14. When requirements are being estimated for particular groups, the user may in the first instance choose the most appropriate example as a guideline. However, it is recommended that, wherever possible, the estimates should be based on actual “profile” studies of the average time spent on different types of activity, particularly where there may be seasonal changes. With this information, the appropriate value for the BMR factor can be calculated by the methods given in section 6.

The figures in Tables 42–47 were derived as estimates of energy expenditure. They may be equated, without further correction, to average requirements for dietary energy intake from a standard diet to which it is appropriate to apply the usual Atwater factors. For diets that contain large amounts of “unavailable” energy (section 7.1), a correction has to be applied (see section 8.6).

8.2.2 Protein

For adults the protein requirement per kg body weight is considered to be the same for both sexes at all ages and body weights within the acceptable range. The value accepted for the safe level of intake is 0.75 g per kg per day, in terms of proteins with the digestibility of milk or egg.

8.3 Adolescents

Because of the variable timing of the adolescent growth spurt, it is recommended that estimates of requirements should be based on weight rather than age, provided that the weight is within the acceptable range of weight for height. Age ranges are given in Table 48 as a general guide in cases where body weights are not known.

8.3.1 Energy

Full details are given in Table 28 and Annex 7. The requirements in Table 48 are based on the Consultation's estimate of desirable levels of physical activity which is so important for the development of children and adolescents. When they are even more active physically, their requirements will naturally be increased.

^a Values of BMR/kg are presented for ease of calculation by those who wish to use different BMR factors.
^b Calculated for each weight from the equations in Table 5 (rounded values).
^c At 0.75 g per kg of protein with the quality and digestibility of milk or egg.

^a Values of BMR/kg are presented for ease of calculation by those who wish to use different BMR factors.
^b Calculated for each weight from the equations in Table 5 (rounded values).
^c At 0.75 g per kg of protein with the quality and digestibility of milk or egg.

^a Values of BMR/kg are presented for ease of calculation by those who wish to use different BMR factors.
^b Calculated for each weight from the equations in Table 5 (rounded values).
^c At 0.75 g per kg of protein with the quality and digestibility of milk or egg.

^a Values of BMR/kg are presented for ease of calculation by those who wish to use different BMR factors.
^b Calculated for each weight from the equations in Table 5 (rounded values).
^c At 0.75 g per kg of protein with the quality and digestibility of milk or egg.

^a Values of BMR/kg are presented for ease of calculation by those who wish to use different BMR factors.
^b Calculated for each weight from the equations in Table 5 (rounded values).
^c At 0.75 g per kg of protein with the quality and digestibility of milk or egg.

^a Values of BMR/kg are presented for ease of calculation by those who wish to use different BMR factors.
^b Calculated for each weight from the equations in Table 5 (rounded values).
^c At 0.75 g per kg of protein with the quality and digestibility of milk or egg.

^{a, b, c} See notes to Tables 42–47

^a From NCHS, average of boys and girls at mid-point of age range.
^b From Table 21 up to 1 year; from Table 23 for 1–10 years.
^c In terms of protein with the digestibility and quality of milk or egg.
^d From Table 33, rounded to nearest 0.05 g.
^e Rounded to nearest 0.5 g.

8.3.2 Protein

The derivation of the safe level of protein intake is shown in Table 34. No adjustment is at present recommended for protein quality, other than for digestibility (section 7.3.3).

8.4 Infants and children

It is recommended that the calculation of both energy and protein requirements for this age group should be made in two steps: first, the requirement per kg should be obtained, according to the age range; secondly, this should be multiplied either by the actual weight, or by the median weight for age, to obtain the total requirement (Table 49).

Rather narrow age ranges are given up to 3 years because until this age the requirement per kg for protein changes rapidly. Thereafter, the energy requirement per kg changes relatively more than the protein requirement.

The body weights shown in the table are presented as a guideline, to be used when actual weights are not known. Within each age range there may be an almost 2-fold variation in acceptable body weight. For more detailed calculation of the requirements of children, if actual weights are not available, the user should obtain the median weight at the actual age from the NCHS tables.

Adjustments for protein quality, according to age, should be made as set out in Table 40.

8.5 Pregnancy and lactation

The extra energy and protein requirements for pregnancy and lactation are shown in Table 50.

Although during pregnancy the requirements increase from the first to the third trimester, the pregnant woman is able to store energy and perhaps protein during the early stages for use later (see section 6.2.1.2). Therefore only a single figure is given for the extra amounts needed per day throughout pregnancy.

In lactation it is assumed that part of the extra energy requirement for milk production during the first 6 months is derived from fat stores laid down during pregnancy (section 6.2.2). It is accepted that, for the protection of the infant, breast-feeding should be continued for longer when possible. However, there is no implication that the extra requirements proposed in Table 50 for lactation from 6–24 months will enable the mother to produce enough breast milk to satisfy the infant's energy and protein requirements.

Table 51. Corrections for digestibility and quality of the diet when intakes are being matched with requirements

A. The method recommended for general use is to correct the diet
Corrections for available energy
The apparent energy content of the diet is obtained by using the Atwater factors:
	Protein	4 kcalth (17 kJ) per g
	Carbohydrate	4 kcalth (17 kJ) per g
	Fat	9 kcalth (38 kJ) per g
For diets containing low amounts of fibre:
available energy = calculated energy × 1.0
For diets containing moderate amounts of fibre:
available energy = calculated energy content × 0.975
For diets containing large amounts of fibre (e.g., all vegetable):
available energy = calculated energy content × 0.95
Correction of dietary protein for digestibility and quality
The total protein content of the diet = total N × 6.25
The biological value of the diet = total protein × digestibility factor × amino acid score
	• the digestibility factor being the digestibility relative to that of the reference protein (egg or milk), expressed as a percentage; (see Table 36)
	• the amino acid score as expressing the amino acid pattern as a percentage of the appropriate reference pattern for each age group (see Table 40)
These corrected intakes are then compared with the requirements shown in the previous tables.
B. The alternative method is to correct the requirement
The “standard” requirements are those given in the preceding tables.
Energy. The apparent energy content of the diet is obtained by applying the Atwater factors (as under A)
When diets contain low amounts of fibre:
	corrected requirement = standard requirement × 1.0
When diets contain moderate amounts of fibre:
	corrected requirement = standard requirement × 1.025
When diets contain high amounts of fibre:
	corrected requirement = standard requirement × 1.05
Protein. The total protein content of the diet = N × 6.25
The corrected requirement in terms of the diet consumed is:
The amino acid score is that appropriate for each age group.
The corrected requirements are then compared with observed intakes.

8.6 Corrections for the quality of the diet

Table 51 shows the method of applying corrections for the composition of the diet so that the available energy can be matched with the average energy requirement while the utilizable protein can be matched with the safe levels of protein intake given in the tables. The method proposed is the converse of that recommended in the report of the 1971 Committee (1), in which the corrections were applied to the estimates of requirements.

REFERENCES

1. FAO Nutrition Meetings Report Series, No. 52; WHO Technical Report Series, No. 522, 1973 (Energy and protein requirements:) report of a Joint FAO/WHO Ad Hoc Expert Committee).