The most used anthropometric indicators are stunting (H/A), wasting (W/H), and underweight (W/A), and mid-upper arm circumference (MUAC) in children under five years of age and Body Mass Index (BMI) in adults.

The term “stunting” is used to describe a condition in which children fail to gain sufficient height, given their age. Stunting is an extremely low “height- for-age” (H/A) score. Stunting is often associated with long- term factors such as chronic malnutrition, especially protein-energy malnutrition, and frequent illness. It is therefore an indicator of past growth failure and is often used for long-term planning of policies and intervention programs in non- emergency situations.  Stunting is very sensitive to socio-economic inequalities.

The term “wasting” refers to a situation where a child has failed to achieve sufficient weight for height (W/H). Weight-for height is normally used as an indicator of current nutritional status. Wasting may be the consequence of starvation or severe disease. It can also be due to chronic conditions or a combination of both.

The term “underweight” is used to describe a situation where a child weighs less than expected, given his or her age. Underweight is thus an extremely low “weight- for-age” (W/A) score. W/A reflects body mass relative to age. Unlike height, weight fluctuates over time and therefore reflects current and acute as well as chronic malnutrition. W/A is commonly used for monitoring growth and to assess changes in the magnitude of malnutrition over time.

The recommended reporting system of H/A, W/H and W/A is in terms of Z- scores— a statistical measure of the distance from the median (mean) expressed as a proportion of the standard deviation. The most common cutoff point is –2 Z-score, i.e., two standard deviations below the median values of the international reference. This is the cutoff risk level used to differentiate malnourished children from those adequately nourished. Children whose H/A, W/H and W/A scores fall below this point are therefore considered, stunted, underweight and wasted, respectively. The WHO has proposed a classification scheme for population-level malnutrition.

MUAC is a measure of the diameter of the upper arm, and gauges both fat reserves and muscle mass. It is primarily used for children, but can also be applied to pregnant women to assess nutritional status. Measurement is simple and requires minimal equipment. MUAC has therefore been proposed as an alternative index of nutritional status, in particular in situation where data on height, weight, and age are difficult to collect.

BMI is a measure to define overweight and thinness. BMI is defined as the weight in kilos divided by the square of height in meters. The BMI is primarily used to identify chronic energy deficiencies (or obesity) in adults.  BMI is the indicator used to assess adult nutritional status in both stable contexts and emergencies. It is of particular importance in areas where adults may be as vulnerable to malnutrition as children. WHO has proposed BMI cut-offs for adults as follows: