7MNT0004 Anthropometry (Week 2)

Anthropometric Assessment - Study Notes

Course Information

• Course Code: 7MNT0004

• Date: Oct 9th 2025

• Instructor: Dr. Karen O’Callaghan

• Department: School of Life Course & Population Sciences

• Faculty: Life Sciences & Medicine

Learning Outcomes

• Explain the Importance of Anthropometric Assessment

• Describe Various Anthropometric Methods and When to Use Them

• Identify the Strengths and Limitations of Different Anthropometric Methods

Introduction to Anthropometry

• Definition: The scientific study of the measurements and proportions of the human body.

• Core Elements:

  • Height

  • Weight

  • Circumferences

  • Various ratios.

Importance of Anthropometric Assessment

• Part of the ABCDEF Approach:

  • Used in nutritional assessment to:

  • Measure physical growth and body composition of individuals/populations.

  • Identify health risks associated with increased/decreased body weight/adiposity.

  • Monitor changes in body composition and characterize energy balance.

  • Generate reference data (e.g., population comparisons).

General Principles for Assessing Anthropometry

1. Procedure:

   • Ensure there is a standardized or protocolized approach.

   • Understand what exactly is being measured.

2. Time/Burden:

   • Evaluate the time required for measurement and if critical information is obtained.

   • Understand time-dependent measurements (e.g., height/weight can vary with time of day).

3. Patient & Consent:

   • Consider the relevance to the patient and context.

   • Assess if the patient’s anatomy/functionality allows for measurement.

   • Confirm consent has been obtained from the patient.

4. Equipment:

   • Use appropriate, calibrated equipment.

   • Portable equipment is preferable.

5. Assessor:

   • Assessor must have the necessary training and skills for reliable and accurate measurement.

6. Interpretation:

   • Determine how measurements will be interpreted.

   • Utilize population-specific reference data and diagnostic criteria as needed.

Overview of Common Measurement Methods

• Methods utilized for measuring physical size often include:

  • Standing height

  • Recumbent (supine) length/height

  • Knee height (surrogate measure)

  • Arm span (surrogate measure)

  • Ulna length (surrogate measure).

Measuring Body Height

1. Standing Height:

   • Target Group: Individuals aged 2 years and older.

   • Equipment: Stadiometer (standardized measurement).

   • Process:

     • Shoes removed, head positioned in the Frankfurt plane.

     • Measurement taken at maximum inspiration.

     • Assessor’s eyes level with the measurement headpiece.

     • Repeat measurements ideally taken at the same time of day, typically in the morning when participants are taller.

2. Recumbent Length:

   • Target Group: Individuals less than or equal to 85 cm or under 2 years of age.

   • Process:

     • Use horizontal length scale/length board.

     • Results usually yield values slightly higher (about ~1 cm) than standing measures.

3. Knee Height:

   • Target Group: Elderly or those unable to stand, adults with spinal deformities.

   • Equipment: Sliding blade caliper or measuring tape.

   • Equations: Population-specific equations (e.g., Chumlea equations) consider height and age derived from knee measurement.

   • Examples of Equations:

     • Non-Hispanic Black Females: 89.58 + (1.61 imes ext{knee height}) - (0.17 imes ext{age})

     • Non-Hispanic White Females: 82.21 + (1.85 imes ext{knee height}) - (0.21 imes ext{age})

     • Non-Hispanic White Males: 78.31 + (1.94 imes ext{knee height}) - (0.14 imes ext{age})

     • Non-Hispanic Black Males: 79.69 + (1.85 imes ext{knee height}) - (0.14 imes ext{age})

4. Arm Span and Demi Span:

   • Used as surrogate measures related to stature.

   • Assessed by extending arms fully, requiring two assessors for accurate measurement.

   • Correlates in a normal growth pattern: arm span:height ratio of 1:1.

5. Ulna Length:

   • Quick and easy measurement useful when spinal curvature exists.

   • Derivation of height is based on the measurement between the olecranon process and the styloid process of the wrist.

   • Validity in different ethnicities may vary (i.e., risk of overestimation in certain populations).

Body Circumferences

• Important for Inferring Body Composition:

  • Key Sites of Measurement:

  • Mid-upper arm circumference (MUAC)

  • Waist

  • Hip

  • Chest

  • Neck

  • Calf

  • Mid-thigh

  • Head for developmental monitoring (in children).

Waist Circumference Measurement

• Taken in a standing position at the end of an exhale.

• Measurement position is critical and varies across groups for consistency.

• Repeat measures are important.

Hip Circumference Measurement

• Similar to waist circumference, to be measured standing at the widest level of the buttocks, with tape level and parallel to the floor.

• Repeat measurements are required for accuracy.

Head Circumference Measurement

• Aimed at children less than 5 years old.

• Reflects brain growth and development.

• Process involves tape placed above ears and eyebrows, across the frontal bone and around the back of the head.

Limitations of Body Weight Measures

• Body weight, circumferences, and related indices are crude population-level measures that fail to provide detailed insight into individual body composition.

• They do not accurately distinguish between adipose tissue and lean body mass.

• Varied risks associated with weight and BMI vary across populations and ethnicities.

• BMI is debated for its effectiveness in characterizing health statuses.

Components of Body Composition

• Fat Mass (FM): All adipose tissue.

• Fat-Free Mass (FFM): All non-fat tissue including bone.

• Lean Soft Tissue (LST): Non-bone, non-fat tissue including skeletal muscle.

• Skeletal Muscle Mass (SMM): The muscle component crucial for locomotion and posture.

Multi-Component Models for Body Composition

1. 2 Component: Fat Mass, Fat-Free Mass.

2. 3 Component: Fat Mass, Total Body Water, Fat-Free Mass.

3. 4 Component: Fat Mass, Total Body Water, Protein, Minerals.

Methods of Measuring Body Composition

Skinfold Thickness Measurement

• Made using skinfold calipers to estimate subcutaneous fat.

• Commonly selected sites for skinfold include axilla, triceps, subscapular, suprailiac, mid-thigh, chest, and abdominal areas.

• High degree of training necessary; methods are field-friendly.

Air Displacement Plethysmography

• Utilizes pressure-volume relationships to estimate body density.

• Two components measured: Fat Mass and Fat-Free Mass.

• Known trade names include BODPOD and PEAPOD.

Bioelectrical Impedance Analysis (BIA)

• Field-friendly method estimating body composition through electrical impedance.

• Recognizes low resistance in lean tissue compared to fat.

• Known trade names include Tanita.

Dual X-ray Absorptiometry (DXA/DEXA)

• Gold Standard for body composition assessment.

• Provides a comprehensive analysis across anatomical sites and very low intra-individual variability

• Requires considerations for positioning and equipment specifics.

Choosing the Right Body Composition Method

• Methods vary in cost, portability, participant burden, and required training.

• Final choice often hinges on specific research questions and practical circumstances.

Weight Stigma

• Acknowledges biases and societal stigmas surrounding body weight, impacting individuals' experiences.

• Emphasizes language sensitivity in clinical settings to reduce weight discrimination.

Resources and Further Reading

• Webpages:

  • DAPA Toolkit: https://www.measurement-toolkit.org/anthropometry/anthro-splash

• Journal Articles:

  • Zemel et al. Body composition indices in children.

  • Heymsfield et al. Discussion on body mass components.

Revision Questions

• Describe three methods for fat-free mass or lean mass assessment and their strengths and limitations.

• Explain the differences among fat-free mass, lean soft tissue mass, and skeletal muscle mass.