The assessment of the nutritional status is accomplished by carrying out the following investigations :
A. Clinical Examination.
B. Anthropometric Measurements.
C. Laboratory and Biochemical Examination.
D. Dietary Surveys.
E. The Study of Vital Statistics.
F. Assessment of Ecological Factors.

A. Clinical Examination
It is the simplest and most essential part of all nutritional surveys. There are a number of physical signs, both specific and non-specific known to be associated with the state of malnutrition. The subject is examined from head to foot in good illumination for the presence or absence of these signs. To minimize subjective and objective errors in clinical examination, standard survey forms or schedules have been devised covering all areas of the body.

B. Anthropometric Measurements
Anthropometric examination includes body measurements such as height, weight, armcircumference. These are important tools in the evaluation of nutritional status of individuals or groups: The following basic measurements are made in nutritional surveys.
i) Height and Weight
ii) Arm Circumference
iii) Skinfold Thickness
In young children additional measurements such as head circumference and chest circumference are made. Anthropometric measurements although genetically determined, are strongly influenced by nutrition. These measurements, if correctly recorded and interpreted, reflect
the pattern of growth and physical state of individuals. They also indicate how the individual deviate from the average at various ages in body size, build and nutritional status. Anthropometric data can be collected by non-medical personnel given sufficient training.

i) Height and Weight : They are most fre quently re corded in nu tri tional sur veys.

a) Height : Height should be taken by mak ing an in di vid ual stand bare foot on a flat floor with feet par al lel and heels, but tocks, shoul ders and back of the head touch ing the wall. The head should be held com fort ably with arms hang ing at the sides. If height ma chine is not avail able, a mea sur ing scale fixed to the wall can also be em ployed. A steel mea sur ing tape is rec om mended to avoid er ror due to loose ness of the or di nary tape. A scale should be placed on top of the head of an in di vid ual, com press ing the air and a mark should be made on the wall at this point. The height can then be mea sured to near est half centimeter (Fig: 1).

To measure the length of infants, infantometer is used. A new born baby's length is 48-50 cm and by the end of the first year it become one and a half times of birth length. An infantometer consists of a wooden board on which the child is made to lie flat on his back. On lying, the child's head touches the head-board of themachine and the feet touches the sliding board. The knees of the child are pressed towards the sliding board and the scle on the infantometer is used to measure the child's length.

b) Weight : Weight should be taken with min i mum cloth ing, with out the foot-wear and should be re corded to near est quar ter ki lo gram. For cor rect re cord ing of weight, le ver bal ances are rec om mended than the spring type bal ances. The sub ject should be made to stand erect and should not touch anything.
Weight is an important index of growth and physical development of a child. The average birth weight of an infant is 3 kg, which doubles by 5 to 6 months, and trebles it by the end of first year. If the birth weight is less than 2.5 kg, then the child is a low birth weight baby. During infancy, weekly gain in weight is taken for assessment of normal rate of growth. The increment in weight after one year is 2.5 kg/year and it is 2.0 kg/year during third and fourth year.
The growth spurts start at the age of 10 to II years in case of girls and 12 to 13 years in case of boys. The growth spurt is maintained for about 2 years in both the sexes. During this period boys gain about 20 kg and girls about 16 kg respectively.

For taking weight, all the measurements should be standardised and instruments must be checked frequently. In a clinic a beam type weighing scale should be used because it is more accurate  This beam balance constitutes a tray, on which the infant is laid down with minimum of clothing. For adults and childrenplatform beam balance is used. Spring balance also has pans for weighing infants. Salter scales are conventionally used in ICDS (Integrated Child Development Services) centres or Aanganwadis for measuringolder children (above 5 months). The child is made to wear a weighing pant and then its loops are hung on the hooks of the scale . Salter scale can be hung on any projection on the wall or door. The machine has the capacity to weigh upto 20 kg and weighs to the nearest 100 gms.

c) Age As sess ment : It is equally im por tant to re cord the age of the in di vid ual cor rectly for proper in ter pre ta tion. The in ter na tional con ven tion of ex press ing age at tile last birth day should be followed.
i) Weight for Age : Weight for age has been used as an in dex of mal nu tri tion. The ma jor dif fi culty is that in many com mu ni ties the age of chil dren are not known.
ii) Height for Age : In adults it is not im por tant since max i mum height is already attained but in chil dren mea sure ment of height or length is very im por tant. The ex tent of height def i cit in re la tion to age is re garded as a mea sure of the du ra tion of malnutrition.

iii) Weight for Height : This index is independent of age. It is regarded as an index of current nutritional status.
Although height and weight are important measurements, too much relevance cannot be placed on them in assessing the nutritional status of individuals. Underweight does not necessarily mean poor nutrition and normal weight does not necessarily mean good nutrition. But when there is supportive evidence of malnutrition, the value of these indices is greatly enhanced. For assessment the nutritional status of children, a single set of height and weight measurements are of little value. The measurements have to be repeated at definite intervals, only then will they become successful.

2) Mid-arm Circumference : This is an easy and useful measurement. The middle of the upper arm is measured while it is hanging relaxed at the side of the body. Normally, the arm circumference increases rapidly from birth to 1 year from 11 to 16 cms. Between the first and 5th birthdays, it remains fairly constant at about 16 to 17 cm in well nourished children and can be used as an age independent method. A measurement below 80 per cent of normal i.e., 12.5 cm indicates severe malnutrition and between 12.5cm and 13.5 cm indicates moderate malnutrition. Health workers can use tapes with green, yellow and red color indicators indicating normal, moderate malnutrition and severe malnutrition respectively. This is a useful method for illiterate workers but should be mainly used as a screening procedure for severe malnutrition. For a quick nutrition survey, a bangle with an internal diameter of 4.0 cm can be used. If it goes over the child's upper arm, the child is severely malnourished (Fig.5).

3) Skinfold Thickness : Skinfold measurements are sometimes used for assessing the nutritional status. The sites commonly used are over the triceps and sub-scapular region. The instrument used is a skin-calliper, which is designed to measure the thickness of the skin and sub-certaneous fat. It provides a measurement of considerable value in assessing the amount of fat and therefore the reserve of calories in the body.
4) Head and Chest Circumference , Head and chest measurements are used to study the prevalence of malnutrition for children. At birth the head circumference is larger than the chest circumference. In an American male infant, the chest circumference overtakes the head circumference by about 9th month. In Indian boys, the crossing over of chest and head circumference takes place around 2 years.

C. Laboratory and Biochemical Examination
i) Haemoglobin Estimation : It is the most important laboratory test that is carried out in nutritional surveys. Haemoglobin level is a useful index of the over-all state of malnutrition.

(ii) Stools and Urine : Stools should be examined for the ova of hookworn, round worm and other parasites. History of parasitic infestation, chronic dysentry and diarrohoea provide useful background information about the nutritional status of persons. Urine should be examined for albumin, sugar and casts.

Biochemical Tests : There are various biochemical tests to measure the individual nutrient concentration and to establish malnutrition, especially in its pre-clinical stages. However. these tests are time consuming and expensive and cannot be applied for the assessment of the whole community. However, these are