10 min readConcept sheetOften a 10-mark answer; BMI sums and MUAC come in Sections A and B

Anthropometry: measurements, BMI and MUAC

Anthropometry measures body size and composition: weight, height, MUAC, circumferences and skinfolds. Simple and cheap, it is the most used method in the field.

BMIWeight (kg) ÷ height (m)²

MUAC, 6-59 months (WHO)Below 115 mm = SAM; 115-124 mm = moderate acute malnutrition

Adult undernutritionBMI below 18.5 = chronic energy deficiency (CED)

Chest-head ratioChest overtakes head in the first year; from 6 months to 5 years a ratio below 1 suggests PEM

Common measurements and what they show

Measurement	Age group	Instrument	What it shows
Weight	All ages	Beam or digital scale; spring (Salter) scale for infants	Present nutritional status; changes quickly
Length or height	Length lying down under 2 years; standing height after 2	Infantometer; stadiometer	Long-term growth (stunting)
MUAC	Children 6-59 months; also pregnant women and adults	Colour-coded MUAC tape (Shakir's tape is the older form)	Muscle and fat; quick screening for SAM
Head circumference	Under 3 years	Flexible, non-stretch tape	Brain growth; small in chronic undernutrition
Chest circumference	6 months to 5 years	Non-stretch tape at the nipple line	Chest-head ratio; below 1 suggests PEM
Skinfold thickness (triceps, subscapular)	Children and adults	Skinfold calipers (e.g. Harpenden)	Body fat stores
Waist and hip circumference	Adults	Non-stretch tape	Abdominal fat; risk of diabetes and heart disease

Activity: taking the measurements correctly

Measure each value twice and take the average. Note age (from the birth certificate or MCP card) and sex.

1★
Weight: set the scale to zero; child in light clothes, no shoes; read to the nearest 0.1 kg. Weigh an infant in a sling on a spring scale.
2
Height: barefoot; heels, buttocks, shoulders and back of the head touching the board; head in the Frankfurt plane (lower eye socket level with the ear opening); lower the headboard; read to 0.1 cm.
3
Length (under 2 years): two people; child lying on the infantometer, head against the fixed board, knees pressed gently straight, footboard against the heels.
4★
MUAC: left arm hanging relaxed; mark the midpoint between the shoulder tip (acromion) and the elbow (olecranon); wrap the tape at the midpoint, snug but not tight; read to the nearest 1 mm.
5
Chest circumference: tape round the chest at the nipple line; read midway between breathing in and out, to 0.1 cm.
6
Head circumference (for the ratio): tape over the most prominent part of the back of the head and just above the eyebrows; take the largest reading.
7
Record at once, compare with standards, and explain the result to the mother.

★ one-way, controls the pace

BMI classes for adults (kg/m²)

Class	BMI	Meaning
CED grade III	Below 16.0	Severe undernutrition
CED grade II	16.0-16.9	Moderate undernutrition
CED grade I	17.0-18.4	Mild undernutrition
Normal	18.5-22.9	Healthy range (Asian cut-offs)
Overweight	23.0-24.9	At risk (Asian cut-offs)
Obese	25.0 and above	Obese (Asian cut-offs); WHO international cut-off is 30

Worked example: BMI of an adult woman

Problem

Meena, an anganwadi helper, weighs 58 kg and is 152 cm tall. Find her BMI and classify it using the Asian cut-offs.

Working

Convert height to metres: 152 cm = 1.52 m.
Square the height: 1.52 × 1.52 = 2.3104 m².
BMI = weight ÷ height² = 58 ÷ 2.3104 = 25.10 kg/m², rounded to one decimal = 25.1 kg/m².
Compare: the Asian cut-off for obesity is 25.0 and above.

Answer

BMI ≈ 25.1 kg/m²: obese by the Asian cut-offs, though only overweight by the WHO international cut-offs. Measure her waist too (80 cm or more is abdominal obesity in women).

Advantages vs limitations of anthropometry

AdvantagesSimple, cheap, quick, non-invasive; portable equipment; can be done by trained field workers such as anganwadi workers; good for screening large numbers and following trends.

LimitationsCannot show which nutrient is lacking; errors from poor technique, faulty scales or unknown age; oedema hides weight loss; small short-term changes may be missed.

In the community

On every Village Health, Sanitation and Nutrition Day, the anganwadi worker weighs children and checks MUAC with a colour tape. A reading below 115 mm means immediate referral, so careful technique matters more than costly equipment.

Exam angle

2 marks: “What is MUAC? Give its cut-off for SAM.” Mid-upper arm circumference, measured at the midpoint of the left upper arm. Below 115 mm in children 6-59 months means severe acute malnutrition (WHO).

5 marks: “Calculate the BMI of a woman who weighs 58 kg and is 152 cm tall, and interpret it.” 1.52² = 2.3104; 58 ÷ 2.3104 = 25.1 kg/m²; obese by the Asian cut-offs (25 and above), overweight by WHO international cut-offs.

10 marks: “What is anthropometry? Describe the anthropometric measurements used to assess nutritional status and their significance.” Define; table of measurements (weight, height, MUAC, head, chest, skinfolds, waist) with instrument and meaning; correct technique; BMI with CED grades and a worked sum; MUAC cut-offs; advantages and limitations.

Remember it

Weight = now, height = history. MUAC in mm: below 115 SAM, 115-124 moderate, 125 and above normal.