I. Skinfold thicknesses at four sites -biceps, triceps, subscapular and supra-iliac -and total body density (by underwater weighing) were measured on 209 males and 272 females aged from 16 to 72 years. The fat content varied from 5 to 5 0 % of body-weight in the men and from 10 to 61 % in the women. 2.When the results were plotted it was found necessary to use the logarithm of skinfold measurements in order to achieve a linear relationship with body density.3. Linear regression equations were calculated for the estimation of body density, and hence body fat, using single skinfolds and all possible sums of two or more skinfolds. Separate equations for the different age-groupings are given. A table is derived where percentage body fat can be read off corresponding to differing values for the total of the four standard skinfolds. This table is subdivided for sex and for age. The fat content of the human body has physiological and medical importance. It may influence morbidity and mortality, it may aIter the effectiveness of drugs and anaesthetics, and it may affect the ability to withstand exposure to cold and starvation. Thus the measurement of the total body fat provides useful information.In many people, but by no means everyone, a moderately satisfactory estimate of the body fat content can be obtained from the height and weight. However, for more precise evaluation several methods are available which give a reasonably accurate measure of body fat both in normal subjects and in individuals with unusual body builds. Most of these methods are based on the assumption that the body can be considered to consist of two compartments of relatively constant composition but which are distinctly different; these compartments are: (I) the body fat, which includes the entire content of chemical fat or lipids in the body, and (2) the fat-free mass (FFM), which includes all the rest of the body apart from fat.The body fat compartment is anhydrous, contains no potassium and has a fairly constant density of about 0.90 x 103 kg/m3. The fat-free compartment on the other hand probably has a fairly constant density of about 1.10 x 103 kg/m3, a potassium content of about 68 mequiv./kg in males (about 10% less in females) and a water content of about 720 g/kg. Thus measurement of body density or of total body K or of total body water allows a calculation of the relative proportion of these two compartments in the body and therefore also of the total fat content. The accuracy of these measures, however, is limited by the variability of the composition and density of the fat-free compartment in different individuals. In particular, individuals with a relatively high or low proportion of bone (which has a low water and K content but a high density compared with the rest of the FFM) may have their fat content under-or over-estimated by these methods. Very little information is available on the variability of the bone content of the body. Similar considerations apply, although to a lesser degree, to individuals who have an abnormally hig...

I . Skinfold thickness and body density were measured on 105 young adult men and women 2. The correlation coefficients between the skinfold thicknesses, either single or multiple, A simple method of assessing quantitatively the fat content of the human body, which could be used not only in laboratories and in hospital, but in field studies and in general medical practice, would be invaluable. Methods in use at present, based on measurements of body density, body water or body potassium, can be applied only in the laboratory and usually to small numbers of subjects.Several previous papers have suggested relationships between one of the accepted methods of determining body fat and a simpler technique which could be widely applied. As early as 1921, Matiegka (1921) formulated an equation for calculating body fat from measurements of surface area and six skinfold thicknesses. Brotek & Keys (1951) were the first to use the relationship between skinfold thickness and body density for assessing fat content. The skinfolds chosen were not ideal and their formula has not been widely used. Pascale, Grossman, Sloane & Frankel (1956) in the USA produced an equation, and PaPizkovL (1961 a ) in Czechoslovakia a nomogram, for predicting fat content from skinfold thicknesses. Steinkamp, Cohen, Gaffey, McKay, Bron, Siri, Sargent & Isaacs (196 j ) gave predictive equations based on measurements of body circumferences and skinfold thicknesses on 167 subjects in California. The only comparable attempt on a British population, to our knowledge, is a study on twenty-four hospital patients, measurements being made of total body water and skinfold thickness (Fletcher, 1962).Information about a wide range of body types in population groups in Britain is required. The present paper describes a study on 105 young adults and 86 adolescents. By means of results from measurements by anthropometry including skinfold thicknesses and body density, an attempt has been made to formulate simple equations for the prediction of the quantity of fat in the body. The subjects were of varying body build-thin, intermediate, plump, but very few were obese.https://www.cambridge.org/core/terms. https://doi

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I .The intake and excretion of total nitrogen, fat and the various forms of carbohydrate, and the heats of combustion of the diet, urine and faeces were measured in groups of young men, young women, elderly men and elderly women.2. Each group was studied while the subjects were eating two diets in turn, which differed in their contents of unavailable carbohydrate; the young women were also studied on a third diet which was rich in unavailable carbohydrate.3. Increasing the intake of unavailable carbohydrate resulted in a greater faecal loss of energy, and in most instances of nitrogen and fat. 4.There was no significant effect of sex or age on the apparent digestibility of protein, fat or available carbohydrate.5. The results are used to evaluate the use of calorie conversion factors for calculating the metabolizable energy content of mixed diets.6. These show that for practical purposes the classical Atwater factors can be used to calculate the metabolizable energy of a diet with reasonable accuracy, provided that when available carbohydrate (as monosaccharides) values are used in the calculation a factor of 3.75 kcal/g (15.7 kJ/g) is used.7. The studies demonstrate that the accuracy of any method for calculating the metabolizable energy of a diet is largely determined by the accuracy with which the method is capable of predicting the gross energy of the diet.The measurement of the metabolizable energy supplied by a diet is not technically difficult, but in practice such measurements are time-consuming, expensive and, most important of all, they place quite severe restrictions on the activities and mode of life of the person eating the diet. In addition, a knowledge of the metabolizable energy supplied by the dietary intake is often required in situations where its direct measurement is impossible or, at best, highly impracticable. In these situations the only alternative is to use a procedure for calculating the metabolizable energy of a diet from its chemical composition.The various systems of calorie conversion factors provide a method for performing this calculation. All the systems used at present have their origins in work carried out at the end of the last century and the beginning of the present one (Rubner, 1885; Atwater, 1903).Atwater and his colleagues carried out a considerable amount of experimental work with human volunteers, which has been admirably reviewed by Merrill & Watt (1955), but most of the modifications of the 'classical' Atwater factors have been based on https://www.cambridge.org/core/terms. https://doi

Measurement of body composition is proving increasingly important in clinical nutrition and research. Skinfold thickness is a simple means of estimating body composition which is widely used in children, but there is little information on its validity. There has been a proliferation of equations for estimation of body composition from skinfolds, but some doubt as to their general applicability. The aim of the present study was to validate five currently used equations for this purpose in a sample of 98 healthy prepubertal children (64 boys, 34 girls), mean (SD) age 9-1 (1-7) years by comparison of estimates from each equation with measurements of fatness derived from hydrodensitometry. Differences between methods were determined by calculation of biases and limits of agreement. Limits of agreement between predicted and measured fatness were wide, particularly in the girls, and some distinct biases were apparent. Choice of prediction equation therefore has a substantial influence on the estimate offatness obtained when using skinfolds in children. The existing published equations are associated with large random errors or significant systematic errors. For the time being skinfolds might best be regarded as indices (rather than measures) of body fatness in individuals, or means of estimating body fatness of groups. Estimating the total body fatness of individual prepubertal children using skinfolds, on the basis of this evidence, is not advisable at present. (Arch Dis Child 1995; 73: 305-310)