In addition to arm circumference and skinfold thickness, the distribution of fat in obese patients can be assessed by determining the waist : hip ratio. The waist circumference is measured at its narrowest point and divided by that of the hip at its widest. Ratios greater than 0.80 for women and 0.95 for men increase the risk of developing clinical problems associated with obesity (Table 10.7). Ultrasonography can also be used on soft tissue adipose material. The technique reflects ultrasound waves from internal tissues or organs and the echo patterns are analyzed to form a picture of body tissues called a sonogram. The extent of fat deposition can be accurately determined but is more expensive than other methods and not widely used.
Anorexia nervosa and BN are difficult to identify, given that the patients often take extreme measures to hide the condition and, indeed, often refuse to admit to any problem. Diagnosis relies on a medical history, clinical investigation supported by anthropometric measurements, coupled with a sympathetic psychological assessment.