Glossary
Accuracy: Closeness of measured value to a gold standard or known value; it is related to validity.
Adipose tissue: Loose connective tissue composed of cells that primarily store fat for energy (adipocytes).
Adiposity: The state of having excess body fat.
Air displacement plethysmography: A method of measuring body composition that uses air displacement to measure body volume in a closed chamber.
Bioelectrical impedance analysis: Indirect method of measuring body composition that estimates total body water, fat-free mass, and fat mass by measuring the resistance of the body as a conductor to a small electrical current.
Body composition: The relative proportion of fat and fat-free mass in the human body.
Body fat: A component of the body that is composed of fat cells (adipocytes). It is found under the skin (subcutaneous) or around organs (visceral) as well as in other tissues and organs of the body.
Body mass index: A person’s weight in kilograms divided by the square of height in meters. It can be used to screen for weight categories that may lead to health problems, but it is not diagnostic of the body fatness or health of an individual.
Body weight: The sum of fat and fat-free mass.
Childhood overweight: Body mass index at or above the 85th percentile and below the 95th percentile for children and teens of the same age and sex.
Childhood obesity: Body mass index at or above the 95th percentile for children and teens of the same age and sex.
Dual energy X-ray absorptiometry: A method of measuring body composition that provides total-body and regional estimates of bone mineral, bone-free fat-free mass, and fat.
Extracellular water: The component of extracellular fluid that surrounds cells and provides a medium for gas exchange, transfer of nutrients, and excretion of metabolic end products of the cell.
Fat-free mass: A component of the body that consists of muscle, bone, organs, tissues, and water.
Fat mass: The total proportion of body weight that consists of fat, including fat deposited in non-adipose tissue and adipose tissue.
Growth chart: A tool for assessing child growth and defining obesity that can be based on data from a reference population (growth reference) or a standard population (growth standard).
Growth reference: A growth chart that is used to assess child growth as compared to children from a reference population. It is based on data from a specific population at a point in time.
Growth standard: A growth chart that is used to assess optimal and desirable child growth. It is based on data from children who were assumed to have optimal growth as a result of being exposed to a variety of factors that promote optimal growth such as mode of feeding, term birth, health care, etc.
Intracellular water: Fluid contained within cells.
Lean mass: Body mass that consists of organs, bone, the brain, water, and muscle.
Measure: Tools and methodologies used to assess body composition such as instruments and electrical devices.
Measurement: The size, length, or amount of something, as established by measuring.
Method: Means in which body composition can be assessed both directly and indirectly.
Population-level research: The field of research that seeks to characterize, explain, and/or influence the levels and distributions of health within and across populations.
Precision: The closeness of the values of two or more repeated measurements to each other; it is related to reliability.
Physical activity: Bodily movement produced by skeletal muscles that results in energy expenditure.
Reference population: The standard against which a population that is being studied can be compared.
Reliability: The consistency with which something is measured.
Skinfold thickness: An indirect method of measuring body composition that estimates the thickness of the subcutaneous fat layer at specific sites on the body.
Subcutaneous adipose tissue: Fat found just below the skin that is typically not related to many obesity-related diseases.
Technical error of measurement: Common way to express the error margin in anthropometry.
Total body water: The sum of intracellular water and extracellular water.
Validity: The truthfulness, or accuracy, of the value obtained or the closeness of a measured value to a gold standard or known value.
Visceral adipose tissue: Fat stored within the abdominal cavity surrounding several major organs. Excess visceral adipose tissue is linked to numerous obesity-related diseases. Also referred to as visceral fat.
Visceral fat: See visceral adipose tissue.
Waist (abdominal) circumference: A measurement of the circumference of the body at the level of the waist, which provides an indirect estimate of body composition and information on body fat distribution.
Z-score: The numerical measurement of a value’s relationship to the mean, represented in terms of standard deviations from the mean. It can be calculated for BMI as well as other measures used in research.