What is Body Composition?

The relative proportion of fat and fat-free tissue in the body.

Why assess body composition?

Helpful for establishing optimal weight for health and physical performance.

What is overweight?

body weight in excess of a standard weight in relation to height.

What is obesity?

surplus of adipose tissue.

What are types of fat?

Subcutaneous vs. Visceral.

What are height and weight measurements based on?

Height and Weight Charts; Metropolitan Life Insurance Company’s height/weight tables (1959); Base on a limited sample of people; Frame size based on wrist or elbow circumference.

What is Body Mass Index (BMI; Quetelet index)?

Used to assess weight relative to height; BMI = (kg . m-2) = Wt (Kg) / Ht (m2).

What are BMI norms?

Underweight <18.5; Normal/Desirable 18.5-24.9; Overweight 25-29.9; Obese (Grade I) 30-34.9; Obese (Grade II) 35-39.9; Obese (Grade III) >40.

What are guidelines for circumference measurements?

Measure circumference of body parts; Gulick tape measure (spring loaded); Do not compress adipose tissue; Make measures in duplicate; Avg if within 5mm; Rotate through measures; Sites: abdomen, arm, buttocks/hips, calf, forearm, hips/thigh, mid-thigh, waist; Waist-to-hip ratio.

How is arm circumference measured?

With the subject standing erect and arms hanging freely at the sides with hands facing the thigh, a horizontal measure midway between the acromion and olecranon processes.

How is forearm circumference measured?

With the subject standing, arms hanging downward but slightly away from the trunk and palms facing anteriorly, a measure perpendicular to the long axis at the maximal circumference.

How is abdomen circumference measured?

With the subject standing, take a horizontal measure at height of iliac crest, usually at the level of the umbilicus.

How is waist circumference measured?

With the subject standing, arms at the sides, feet together, and abdomen relaxed, a horizontal measure is taken at the narrowest part of the torso (above the umbilicus and below the xiphoid process).

How are buttocks/hips measured?

With the subject standing erect and feet together, a horizontal measure is taken at the level of the maximal circumference of the buttocks; This measure is used for the hip measure in a waist/hip measure.

How are hips/thigh measured?

With the subject standing, legs slightly apart (about 10cm), a horizontal measure is taken at the maximal circumference of the hip/proximal thigh, just below the gluteal fold.

How is mid-thigh measured?

With the subject standing and one foot on a bench so the knee is flexed at 90°, a measure is taken midway between the inguinal crease and the proximal border of the patella, perpendicular to the long axis.

How is calf circumference measured?

With the subject standing erect (feet apart about 20cm), a horizontal measure is taken at the level of the maximum circumference between the knee and the ankle, perpendicular to the long axis.

What is waist-to-hip ratio (WHR)?

A comparison between the circumference of the waist to the hips; Use waist and buttocks/hip measures; Very high risk: men >0.95; women >0.86.

What are waist-only risk criteria?

RF criteria; Men > 102 cm (40 in); Women > 88 cm (35 in).

What is android obesity?

apple-shape; more prone to CV disease/hypertension, type-2 diabetes, metabolic syndrome.

What is gynoid obesity?

pear-shape; more associated with mechanical problems.

What are skinfold measurements?

Skinfold thickness is measured at various sites; Assumes subcutaneous fat is proportional to total body fat; Sites: abdominal, tripceps, chest, midaxillary, subscapular, suprailiac, thigh, biceps, calf.

How accurate are skinfold measurements?

Still an estimate or prediction of percent body fat, not an absolute measurement; Technician training is very important; biggest chance for error; Anatomical site selection is also very important; Assuming proper techniques: ~3.5% error.

What are skinfold procedures?

Measure the specific sites; Mark each site; All measurements should be made on the right side of the body with the subject standing upright; Caliper should be placed directly on the skin surface, 1 cm away from the thumb & finger, perpendicular to the skinfold, and halfway between the crest and the base of the fold; Pinch should be maintained while reading the caliper; Wait 1-2 seconds (not longer!) before reading the caliper; Take duplicate measures at each site; retest if within 1-2mm; Average the two measurements for each site (Do not include outliers when averaging sites); Rotate through measurement sites or allow time for skin to regain normal texture and thickness; Sum the mean of each skinfold site.

How is triceps skinfold measured?

Vertical fold; on the posterior midline of upper arm (1/2 way between acromion and olecranon processes) with arm held freely to the side of the body.

How is subscapular skinfold measured?

Diagonal fold (45° angle); 1-2 cm below the inferior angle of scapula.

How is abdominal skinfold measured?

Vertical fold; 2cm to the right side of the umbilicus.

How is suprailiac skinfold measured?

Diagonal fold; in line with the natural angle of the iliac crest taken in the anterior axillary line immediately superior to the iliac crest.

How is midaxillary skinfold measured?

Vertical fold; on the midaxillary line at the level of the xiphoid process of the sternum.

How is chest/pectoral skinfold measured?

Diagonal fold; for men: ½ of the distance between the anterior axillary line and the nipple, for women: 1/3 of the distance between the anterior axillary line and the nipple.

How is biceps skinfold measured?

Vertical fold; on the anterior aspect of the arm over the belly of the biceps muscle, 1cm above the level used to mark the triceps site.

How is thigh skinfold measured?

Vertical fold; on the anterior midline of the thigh, midway between the proximal border of the patella and the inguinal crease (hip).

How is medial calf skinfold measured?

Vertical fold; at the maximum circumference of the calf on the midline of its medial border.

How is body density calculated?

Sum of skinfolds are put into gender/age-adjusted equations to get body density.

How is body fat percentage calculated?

Body density is converted to % body fat via age-ethnicity specific equations.