BPK 142 Body Composition & Anthropometry

Body composition

The relative proportion of different components that make up the human body, including tissues such as nervous, epithelial, muscle, and connective tissues, as well as fat, bone, tendon, cartilage, and other components.

Tissue model

The body is composed of four main tissue types - nervous, epithelial, muscle, and connective tissues - which work together to comprise each organ.

Structural model

The main structural components of the body are bone, fat, and muscle, and the relative proportion of these components can vary based on gender, genetics, age, and lifestyle.

Two-component model

The body is composed of fat and fat-free mass, which includes bone, muscle, vital organs, and connective tissue.

Chemical model

The body is composed of fat, protein, carbohydrates, minerals, and water.

Anthropometry

The quantitative measurement of body size and proportions, used to understand human physical variation and body composition. Methods include skinfold thicknesses, circumferences, bony widths and lengths, height, and body weight.

Co-morbidities/Complications Associated with Obesity

Type II diabetes mellitus, hypertension, coronary artery disease, heart failure, certain cancers, dyslipidemia, inflammatory markers, stroke, sleep apnea, gallbladder disease, nonalcoholic fatty liver disease, osteoarthritis, gout, reduced fertility, impaired obstetric performance, and reduced physical agility.

Co-morbidities/Complications Associated with Excessive Thinness

Fluid-electrolyte imbalances, osteoporosis, bone fractures, muscle wasting, cardiac arrhythmias, sudden death, peripheral edema, renal disorders, reproductive disorders, and eating disorders such as anorexia nervosa, bulimia nervosa, binge eating disorder, and female athlete triad.

Essential Fat vs Storage Fat

Essential fat is required for normal physiological functioning, while storage fat is stored in adipose tissue for energy supply purposes. Storage fat is stored in adipose tissue for energy supply purposes. It needs additional energy for recovery

Body Composition of Males vs Females

Males generally have a larger muscle mass and lower total body fat content compared to females. Females have sex-specific fat in the breasts, pelvic, and thigh regions.

Obesity

The combination of diabetes and obesity is one of the largest epidemics the world has faced, with increasing prevalence and severe health risks. Obesity is associated with decreased longevity, increased healthcare costs, and various co-morbidities.

Causes of the Obesity Epidemic

Weight gain and obesity occur when energy intake exceeds energy expenditure, decreased physical activity, increased consumption of calories, social environment, and genetics.

Body Composition and Aging

Aging is associated with increased fat mass, decreased muscle mass (sarcopenia), and decreased bone mass. Regular exercise and proper dietary habits can slow down these changes.

Common Techniques for Assessing Body Composition (Anthropometry)

Direct methods (chemical analysis of human cadavers) and indirect methods (noninvasive techniques used on living persons) such as height-weight tables, body density and volume measurements, weight-height indices (BMI), waist circumference, and skinfold measurements.

Population specific equations

Equations developed from small, homogeneous samples that have limited application to specific subgroups.

Generalized equations

Equations developed from large, heterogeneous samples that have wider application but should be used cautiously with unique populations.

Age-adjusted percent fat prediction equations

Equations needed to account for the increase in internal fat deposits with advancing age.

Error in percent fat prediction

Approximately 3-4% error when predicting percent fat from skinfold measurements.

CSEP-PATH Body Composition Assessment

A procedure that uses BMI and waist circumference to assess an individual's health risks associated with body composition.

O-Scale System

A system that includes adiposity rating, proportional weight rating, and stanine scale for assessing body composition.

Bioelectrical Impedance Analysis

A method that measures the electrical resistance of the body to estimate body composition.

Daily fluctuations in water content

Fluctuations that need to be standardized for accurate impedance results.

Equations specific to given populations

Equations that should be used based on sex, age, race, and ethnicity.

Error in percent fat estimation

Approximately 3-5% error in estimating body fat percentage.

Other Procedures

Various methods such as DXA, CT, MRI, total body water, ultrasound, total body potassium, and NIR used for body composition assessment.

CT, MRI, and DEXA

Considered "gold standards" for calibration of field methods to measure adipose tissue and lean body mass.

Distinguishing between SAT and VAT

CT, MRI, and DEXA can differentiate between subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT).

Interpretation of body composition results

Results should be interpreted cautiously due to various factors and limitations.

Eating disorder

A disturbance in eating behaviour that jeopardizes a person’s physical or psychological health

Body mass equation

Fat mass + Lean Mass

Causes of the Obesity Epidemic

1. Weight gain and obesity occurs when energy intake exceeds energy expenditure

2. Decreased physical activity

3. Increased consumption of calories

4. Social environment

5. Biology - occurring on genetic backgrounds

NEAT

non-exercise activity thermogenesis. It is the energy expended by physical activities other than planned exercise

Directed methods

chemical analysis of human cadavers

Indirect methods

noninvasive techniques used on living persons

Density

Mass/ Volume

Two ways to use fatfolds

1. Use the sum of a number of skin fold as an indication of relative fatness among individuals

2. Use fat folds in conjunction with equations or tables to predict percent body fat

Assumptions in using skin folds measurements to predict percent fat

1. Constant densities in a two-compartment model

2. Proper identification of measurement site and proper measurement technique

3. Constant compressibility of the skin fold

4. Fixed adipose tissue patterning

5. Fixed proportion of internal to external fat