Estimation of Non-Fat Body Tissues from Measurements of Skinfold Thickness, total Body Potassium and Total Body Nitrogen

1983 ◽  
Vol 65 (4) ◽  
pp. 407-414 ◽  
Author(s):  
D. B. Morgan ◽  
L. Burkinshaw
Keyword(s):  
Fat Body ◽  
Skinfold Thickness ◽  
Statistical Technique ◽  
Fat Free Mass ◽  
Variable Component ◽  
Total Body Potassium ◽  
Tissue Mass ◽  
Body Tissues ◽  
Total Body ◽  
The Relationship

1. Many previous reports have shown that the ratio of total body potassium to fat-free tissue mass is, on average, higher in men than in women. 2. In an attempt to explain this finding we have re-examined our own data and data taken from the literature. Our own data comprise measurements on 333 healthy people (196 men and 137 women). In all subjects we measured total body potassium and estimated fat-free mass from body weight and skinfold thickness; in 91 of them (62 men and 29 women) we measured, in addition, total body nitrogen. 3. We have used the statistical technique of factor analysis to obtain unbiased estimates of the relationships between the three quantities measured in the smaller group. The validity of the relationships is supported by the results from the larger group and by data from the literature. 4. The average values of total body potassium and fat-free mass are greater in men than in women, but the relationship between the two variables is identical in men and women. The relationship has a positive intercept on the axis of fat-free mass, so that the ratio of total body potassium to fat-free mass increases with fat-free mass. The higher ratio in men compared with women can therefore be explained by a difference in size alone. 5. The relationship between total body potassium and total body nitrogen has a negligible intercept. Therefore the ratio of total body potassium to total body nitrogen does not change with size. 6. These findings suggest that, on average, the fat-free mass is made up of a fixed component of approximately 9 kg of tissue containing no potassium or nitrogen, and a variable component with a potassium to nitrogen ratio of about 1.81 mmol/g.

A Comparison of the Fat-Free Mass of Young Adults Estimated by Anthropometry, Body Density and Total Body Potassium Content

1972 ◽  
Vol 43 (3) ◽  
pp. 469-475 ◽  
Author(s):  
J. Womersley ◽  
K. Boddy ◽  
Priscilla C. King ◽  
J. V. G. A. Durnin
Keyword(s):  
Young Adults ◽  
Direct Analysis ◽  
Skinfold Thickness ◽  
Fat Free Mass ◽  
Potassium Content ◽  
Body Density ◽  
Total Body Potassium ◽  
The Mean ◽  
Total Body ◽  
Male Subjects

1. The fat-free mass (FFM) of ten male and ten female subjects was calculated from measurement of (i) height and weight, (ii) skinfold thickness, (iii) body density, (iv and v) total body potassium by two different methods. All the subjects were apparently healthy and in the medium range of body build and they were mainly young adults. 2. The mean FFM of the ten male subjects was similar as calculated by all methods, although comparisons between pairs of methods sometimes produced discrepancies of up to 2 kg. 3. Agreement was less good for the females but, with the exception of one of the potassium methods, still reasonable. 4. The potassium content of the FFM as mEq K/kg of FFM, was compared with the direct analysis of Forbes, Gallup & Hursh (1961) on four male cadavers. The agreement was close for the men but the K content of the FFM in women was lower than that for men. This difference is discussed.

Total Body Nitrogen and Its Relation to Body Potassium and Fat-Free Mass in Healthy Subjects

1981 ◽  
Vol 61 (4) ◽  
pp. 457-462 ◽  
Author(s):  
L. Burkinshaw ◽  
D. B. Morgan ◽  
N. P. Silverton ◽  
R. D. Thomas
Keyword(s):  
Standard Deviation ◽  
Healthy Subjects ◽  
Skinfold Thickness ◽  
Mean Value ◽  
The Body ◽  
Fat Free Mass ◽  
Total Body Potassium ◽  
Individual Values ◽  
Total Body ◽  
The Individual

1. The amount of lean tissue in the body can be assessed by measuring total body nitrogen, total body potassium or fat-free mass. To compare these techniques we have measured total body nitrogen, total body potassium and fat-free mass in 91 healthy subjects (62 males, 29 females). 2. Total body nitrogen in the women and civilian men agreed closely with the few values reported previously and was closely related to total body potassium and fat-free mass. 3. The simplest estimate of total body nitrogen in a subject whose body content has not been measured is the mean value for healthy people of the same sex. The standard deviation of individual values about this mean is 253 g. The precision of the estimate can be improved considerably by predicting body nitrogen from fat-free mass (156 g) and somewhat more by predicting it from body potassium (115 g). The error of measuring total body nitrogen directly is approximately 76 g. 4. When an individual's total body potassium is measured in a search for potassium depletion, the observed value must be compared with the value expected if the subject were healthy. The standard deviation of the healthy values about the group means is 408 mmol. The precision of the estimate can be improved by predicting total body potassium from fat-free mass (sd 237 mmol), and rather more by predicting it from total body nitrogen (sd 186 mmol). If gross body composition is normal, measurement of total body nitrogen has little advantage over measurement of fat-free mass by the anthropometric technique. 5. These results suggest that the simpler measure of fat-free mass from body weight and skinfold thickness has a major role in the assessment of total body nitrogen, and thus lean body tissue, in the individual.

Magnitude and variation of ratio of total body potassium to fat-free mass: a cellular level modeling study

2001 ◽  
Vol 281 (1) ◽  
pp. E1-E7 ◽  
Author(s):  
Zimian Wang ◽  
F. Xavier Pi-Sunyer ◽  
Donald P. Kotler ◽  
Jack Wang ◽  
Richard N. Pierson ◽  
...  
Keyword(s):  
Body Fat ◽  
Essential Element ◽  
Physiological Model ◽  
Cellular Level ◽  
Fat Free Mass ◽  
Total Body Potassium ◽  
Fluid Compartment ◽  
Total Body Fat ◽  
Total Body ◽  
Living Organisms

Potassium is an essential element of living organisms that is found almost exclusively in the intracellular fluid compartment. The assumed constant ratio of total body potassium (TBK) to fat-free mass (FFM) is a cornerstone of the TBK method of estimating total body fat. Although the TBK-to-FFM (TBK/FFM) ratio has been assumed constant, a large range of individual and group values is recognized. The purpose of the present study was to undertake a comprehensive analysis of biological factors that cause variation in the TBK/FFM ratio. A theoretical TBK/FFM model was developed on the cellular body composition level. This physiological model includes six factors that combine to produce the observed TBK/FFM ratio. The ratio magnitude and range, as well as the differences in the TBK/FFM ratio between men and women and variation with growth, were examined with the proposed model. The ratio of extracellular water to intracellular water ( E/I) is the major factor leading to between-individual variation in the TBK/FFM ratio. The present study provides a conceptual framework for examining the separate TBK/FFM determinants and suggests important limitations of the TBK/FFM method used in estimating total body fat in humans and other mammals.

Longitudinal studies on adipose tissue and its distribution in human subjects

1975 ◽  
Vol 39 (5) ◽  
pp. 825-830 ◽  
Author(s):  
S. Chien ◽  
M. T. Peng ◽  
K. P. Chen ◽  
T. F. Huang ◽  
C. Chang ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Human Subjects ◽  
Water Immersion ◽  
Skinfold Thickness ◽  
Total Body Potassium ◽  
Body Adiposity ◽  
Hydrostatic Weighing ◽  
Skinfold Measurements ◽  
The Mean ◽  
Total Body

On 27 men and 6 women, total body density and 10 skinfolds were measured 12 yr apart, with the mean age increasing from 31 to 43 yr. The increase in skinfold thickness was found to be related to the increase in total body adiposity, calculated from hydrostatic weighing. The external adipose tissue was calculated from the mean skinfold thickness and body surface area. Variations in total adiposity among the population studied as well as changes in total adiposity with age showed a characteristic distribution with approximately two-thirds on the surface and one-third in the interior. The essential body mass or total adipose mass determined by hydrostatic weighing was compared with the values obtained by water-immersion volumetry, total body potassium counting, and skinfold measurements. Teh volumetric and skinfold determinations gave better estimates of these parameters than total body potassium counting.

Total Body Potassium and Body Fat Estimation in Relationship to Height, Sex, Age, Malnutrition and Obesity

1975 ◽  
Vol 48 (5) ◽  
pp. 431-440 ◽  
Author(s):  
C. J. Edmonds ◽  
B. M. Jasani ◽  
T. Smith
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Body Fat ◽  
Fat Free Mass ◽  
Whole Body ◽  
Regression Equations ◽  
Total Body Potassium ◽  
Normal Individuals ◽  
Males And Females ◽  
Total Body

1. Total body potassium was estimated by 40K measurement with a high-sensitivity whole-body counter in normal individuals over a wide age range and in patients who were obese or were grossly wasted as a result of various conditions which restricted food intake. 2. Potassium concentration (mmol/kg body weight) fell with increasing age over 30 years in both normal males and females, but when individuals of different age groups were matched for height, a significant fall in total body potassium with increasing age was observed only in males. Total body potassium of females was about 75% that of males of similar height when young, the sex difference decreasing with ageing. In the normal population, total body potassium was significantly correlated with height and with weight; regression equations for various relationships are given. 3. Fat-free mass was estimated from total body potassium, values of 65 and 56 mmol of potassium/kg fat-free mass being used for males and females respectively. Body fat estimated by this method correlated well with skinfold measurements over a wide range of body weight but in malnourished individuals having inadequate food intake there was considerable discrepancy and present formulae for estimating fat-free mass from total body potassium appear unsatisfactory in malnutrition. Considerable differences between expected and observed values of total body potassium were found in muscular individuals and in normal individuals who were thin but whose body weight was relatively constant. 4. The patients with malnutrition were low both in body fat as estimated by skinfold thickness and in total body potassium estimated on the basis of height. Plasma potassium was, however, normal and potassium supplements did not increase the total body potassium. 5. Total body potassium of obese individuals was not significantly different from that of normal weight individuals on the basis of height. Total body potassium fell on weight reduction with a very low energy diet of 1260 kJ (300 kcal.) daily but changed little with a 3300 kJ (800 kcal.) diet over several months' observation. 6. For overweight, obese individuals, total body potassium was best predicted from the individual's height. For those whose body weight was less than expected, the use of weight gave the best prediction but the error was considerable when the weight deviation was large.

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