PHYSICAL EXPLORATION AND ANTHROPOMETRIC MEASUREMENTS
This examination establishes the proportion of the different components present in the body (fat, muscle, water) and the changes that have taken place over time.
Apart from the routine physical examination (weight, height, muscle strength, etc.), it is also very important to explore the skin, nails and hair, as well as the mucosa, which may accompany certain conditions due to deficit or excess of nutrients.
a) Weight, height
These are the easiest measurements to take, and basic for the undertaking of more complex tests to assess the nutritional condition of each individual.
The individual must be weighted undressed, standing on a standard scale adjusted to every 100 mg; height must be recorded with the individual standing straight, adjusting measurements to the millimetre and without shoes.
b) Body Mass Index (BMI)
This is the measurement of choice and the most frequently used. BMI is obtained according to the following formula, with the weight being calculated in kilograms and the height in meters:
This index is the best measure to correlate the ratio of fat of the adult individual. Age-adjusted tables have been released showing normal values for women and men according to their age.
Its main disadvantage is that BMI does not distinguish between fat and lean body mass (non-fat mass) and some well muscled individuals may be classified as obese when in fact they are not.
Despite its drawbacks, calculation of the BMI has been established by the different Committees and specialised societies in obesity as the basic measurement of choice for the initial assessment of overweight and obesity in adult individuals. According to the Spanish consensus of the SEEDO 2000, weight is classified as follows:
c) Percentage of ideal weight
The current weight of the individual must be compared to standard weight values. Tables have been elaborated in Spain for specific heights and are age-adjusted for individuals aged 16 to 70 years. The percentage of weight is calculated as follows:
When assessing malnourished patients, the percentage of ideal weight is useful to determine the degree of malnutrition (such malnutrition is classified as severe when the percentage of ideal weight is below 70% and mild when it is above 90%).
The ideal weight refers to how much the individual should weigh for a certain height and with a lower mortality weight. However, on occasions, this ideal weight cannot be applied and in practice it is a term that is not widely used in nutrition.
d) A recent change in body weight
A significant change in body weight in a short period of time may indicate serious nutritional disorders. When these disorders cause the weight loss, they may be related to a greater deficiency of protein intake and a higher risk.
It is calculated using the following formula:
It is suggested that a 10% loss of the usual weight in a 6 month period indicates a significant degree of malnutrition.
e) Nutritional Index (NI)
It correlates the weight and height of the individual with the mean weight and height for his/her sex and age. It is calculated by the following formula:
A NI of 90 to 110% is considered normal; when below 90% it is considered malnutrition, if between 110 and 120% it is considered overweight, and over 120% it is considered obesity.
f) Ponderal Index (PI)
It is one of the best known adiposity indexes, being known by multiple expressions, including the body shape index or Rohrer's index (the ratio of weight to height). It is calculated by applying the following formula, in which the weight is determined in kilograms and the height in meters:
The result yielded by the calculation of the BSI would correspond to the percentage of fat body mass and it would no be affected by height as with the BMI. Thus, this measurement would be more suitable for individual assessment, mainly in adolescents and children. Nonetheless, calculation of the BSI has not gained so far the importance of the BMI, and in daily clinical practice is not extensively used.
g) Measurement of skin folds:
The measurement of different skin folds is performed to determine the degree of adiposity in the subjects. Its utility comes from the fact that subcutaneous fat accounts approximately for 50% of total body fat, and measurement of skin folds would show rather accurately the degree of total adiposity of the individual. This measurement can be carried out in one single measurement or in combination with the measurement of several body areas, thus reducing the error margin and correcting possible differences in the distribution of fat in the same individual.
A calliper is used to carry out the measurement and results are obtained in millimetres. The most commonly measured sites are the tricipital fold (at mid-point between the olecranon and the acromion), the bicipital fold (anterior aspect of the arm at the same height where the tricipital fold is measured) of the non-dominant arm, the subscapular fold (one centimetre below the inferior angle of the scapula with the arms of the patients in relaxation) and the suprailiac fold (two centimetres above the left iliac crest in the mid line). Three measurements of each site are taken and the mean calculated, with this mean being the result of this measurement for each fold.
Several equations exist, which based on the measurements of skin folds, can provide a rather accurate prediction of the percentage of total body fat. The value of one or several separate folds may also be used for comparison with age-adjusted and sex-adjusted reference values. Obesity will be considered when the measurement is over the 90 percentile and malnutrition when the measurement is below percentile 5.
h) Arm perimeter
It consists in the measurement of the arm perimeter at the same height as the measurement of the tricipital and bicipital folds. The perimeter measures the fat and lean compartments of the arm allowing the measurement of the lean perimeter of the arm (LP) by subtracting the value of the tricipital fold from the total perimeter (TP).
Lean muscle perimeter = total arm perimeter -tricipital fold
However, this measurement is not completely reliable as it does not take into account the thickness of the humerus.
i) Cranial perimeter
This measurement is very useful to assess intrauterine growth and in paediatrics to the age of 4 years.
j) Indicative parameters of body fat distribution.
The importance of estimating the distribution of total body fat in the different body compartments (subcutaneous tissue, visceral or intrabdominal fat) as the most reliable method to establish risks related to the presence of obesity. Thus, it is visceral fat (or intrabdominal fat), which poses the greatest metabolic risk for the health of the individual.
After the 80's, several indicators of visceral obesity were suggested such as the waist/hip ratio, waist circumference, waist/muscle ratio, waist/size ratio and the sagittal abdominal diameter.
Waist/hip ratio: This is the most reliable anthropometric measurement for assessing abdominal obesity. Its results correlate extremely well with the amount of visceral fat. It is easy to obtain and reproducible in time. It is calculated as follows:
A measuring tape with millimetres is needed to carry out the test. The patient must be standing with his/her arms relaxed on both sides of the body. The waist perimeter is the minimal circumference between the costal border and the iliac crest. The hip perimeter is the maximal circumference between the waist and the thighs.
A waist/hip index of over 0.9 inn women and over 1.0 in men, has been described as a risk factor for the development of diseases associated with obesity.
Waist circumference: There is growing evidence showing that the single determination of the waist circumference index (in cm) is similar to the waist/hip index. This determination is simple and correlates rather well with the indexes already mentioned and with total body fat. Reference values vary according to the race and the population. Europeans are considered to be at risk when the waist circumference index is over 82 cm in women and over 95 cm in men (the risk is very high for women and men whose waist circumference index is over 90 cm and 102 cm, respectively).