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Association between lean mass, fat mass, and waist circumference with bone mineral density in Mexican children and adolescents: a cross-sectional study.

To assess the associations of lean mass (LM), fat mass (FM), truncal fat mass (TFM), and waist circumference (WC) with bone mineral density (BMD) in Mexican youth, independently of body weight.&#xa0;We analyzed cross-sectional data from 1,054 children and adolescents from the Health Workers Cohort Study. We measured total and region-specific BMD, LM, and FM, with dual-energy X-ray absorptiometry. To eliminate the effect of body weight on FM, LM, TFM, and WC, weight-adjusted values were generated using the residuals method, and then we employed multivariate linear regression models adjusted for relevant potential confounders. We further stratified the analysis by sex, age group, and sexual maturation.&#xa0;LM was positively associated with BMD in various anatomical sites, with &#x3b2; coefficients ranging from 0.004 to 0.013 in both sexes (P&#x2009;<&#x2009;0.05). FM was inversely related to total BMD and other sites, with &#x3b2; coefficients ranging from -0.013 to -0.006 (P&#x2009;<&#x2009;0.05). WC showed negative associations with BMD at some sites, with &#x3b2; values ranging from -0.007 to -0.002. TFM was negatively associated with BMD. During puberty, the associations were consistent across all sites, whereas this was not the case for all sites after puberty. These patterns were similarly observed across different age groups.Conclusion:&#xa0;An increased LM and reduced FM are associated with higher BMD, particularly in the leg and hip regions, during childhood and adolescence, a critical developmental stage essential for healthy bone accrual and balance in adulthood.

Humans

Relationship between body fat mass, carbohydrate tolerance and IRI response during glucose infusion in subjects with early diabetes.

We have studied the interrelationship of total body fat mass, carbohydrate tolerance and IRI response in 17 non-obese and obese subjects, who were suspected of having early diabetes. We carried out an i.v. glucose infusion test consisting of a priming injection of 0.33 g/kg followed by constant glucose infusion of 12 mg/kg/min in all persons. Total body fat mass was estimated by the tritium dilution method. There was a positive correlation of body fat mass, fasting glucose concentration and blood glucose concentration at 150 min as well as a strong correlation between body fat mass and BG area 60--120 min as parameters of carbohydrate tolerance in all subjects, i.e. the degree of carbohyrate intolerance was directly related to the quantity of total body fat mass. A similar correlation was found when the non-obese and obese groups were analyzed separately. In neither group did total body fat mass correlate with parameters of IRI response. In obese subjects with pathological carbohydrate tolerance, however, a positive correlation of basal IRI concentration and total body fat mass was found. Furthermore, a close relation between basal IRI level and parameters of carbohydrate tolerance could be demonstrated in obese subjects. The present study failed to demonstrate any correlation of parameters of carbohydrate tolerance and glucose-induced IRI response in either group. Thus, the significant relationship between body fat mass and degree of carbohydrate intolerance indicates that body fat mass plays an important role in the disturbance of blood glucose homeostasis in early diabetes with and without obesity.

Adipose Tissue

Body composition in middle-aged women with special reference to the correlation between body fat mass and anthropometric data.

A variety of anthropometric measurements was made in a randomized population sample of middle-aged women in five age strata in whom body composition was estimated from total body potassium and total body water determined by whole body counting and isotope dilution technique, respectively. No significant differences with age were found for total body potassium or total body water. A significant age difference was found for body fat mass. Simple linear correlations between anthropometric variables and body fat mass estimates were found to be 0.90, 0.86, 0.77 for body weight, buttock circumference, and sum of triceps and subscapular skinfold thicknesses, respectively. Multiple regression analysis showed that these three variables accounted for 80 to 91% of the variation in body fat in the different age strata studied. Multiple regression equations for prediction of body fat from anthropometric variables are given. In about two-thirds of the subjects, the difference between predicted body fat mass and estimated body fat mass was found to be less than +/- 2.5 kg.

Adipose Tissue

Effects of fat mass reduction by dieting and by lipectomy on carbohydrate metabolism in obese patients.

The interrelation of enlarged body fat mass (BFM) with reduced carbohydrate tolerance and hyperinsulinemia was studied in obese subjects with chemical diabetes. These patients were subjected to lipectomy following weight loss induced by a low-calorie, low-carbohydrate diet. An improvement in glucose tolerance and in insulin sensitivity and a reduction in insulin release during OGTT was observed after a diet-induced BFM loss of 9.9 +/-1.2 kg. Subsequent surgical reduction of BFM by 6.0 +/- 0.5 kg had no further effect upon carbohydrate tolerance, insulin release or insulin sensitivity though a marked decrease in basal plasma FFA values was observed. These findings suggest that fat mass enlargement per se has no effect on blood glucose homeostasis after oral or i.v. loading. The improvement in carbohydrate tolerance and in insulin resistance usually observed following diet-induced loss of BFM seems to be due to the reduction in calorie and carbohydrate intake rather than to decrease of BFM.

Adipose Tissue

[Plasma cortisol response to intravenous beta 1-24 corticotropin as related to the fat mass and its topographic localisation (author's transl)].

Plasma cortisol response induced by 2.5 microgram/kg beta 1-24 corticotropin (1 hour infusion) in obese females was not related to fat mass. The response was increasingly pronounced as fat predominated in the upper body segment, i.e. android obesity. This phenomenon may be interpreted as indicating an increased adrenal capacity to secrete cortisol in such obese patients. Low level but longstanding excess cortisol secretion is probably the cause of the android features of obesity.

Adipose Tissue

Effects of bran on serum cholesterol, faecal mass, fat, bile acids and neutral sterols, and biliary lipids in patients with diverticular disease of the colon.

Twenty-two patients with symptomatic diverticular disease of the colon were randomly allocated to control and high-fibre groups so that the long-term effect (up to 12 months) of bran on serum, faecal and biliary lipids could be studied. Even in cases of high initial values, faecal mass was increased by bran and the change was positively correlated with the change in dietary fibre. Faecal fat and dry weight were also increased. Faecal bile acids were initially slightly raised and were positively correlated with wet weight both off and on bran. The latter significantly decreased the excretion and concentration of bile acids, in particular the high initial values. The change in bile acids was not correlated with the change in dietary fibre or faecal wet weight. Sterol balance values indicated that the bran-induced decrease in faecal bile acids was associated with a lower cholesterol synthesis. Serum cholesterol decreased significantly in two hypercholesterolaemic individuals only. Correlations between different parameters revealed that the higher the initial level or the greater the drop in cholesterol synthesis, the greater the decrease in serum cholesterol. Bran had no effect on the biliary saturation of cholesterol. The percentage of biliary deoxycholate was negatively correlated with faecal mass (less so with faecal bile acid output) both before and during bran and was significantly decreased by bran. The percentage of cholic acid increased correspondingly and that of chenodeoxycholate remained unchanged. Faecal bile acids also indicated that the synthesis of the two primary bile acids was lowered by bran to the same degree.

Adult

Sitting height, fat-free mass and body fat as reference variables for lung function in healthy British children: comparison with stature.

The ventilatory capacity, total lung capacity and transfer factor with their respective subdivisions have been measured on 254 healthy British boy and girl twins aged 8-16 yrs. The logarithmic regression relationships of lung function on stature have been compared with those on sitting height and on stature plus indices of body muscle and fat. The regressions on stature and on sitting height describe the results with similar precision, but stature is marginally better; either index may be used as the reference variable. For the description of inspiratory capacity and of all indices which include this volume (e.g. vital capacity, total lung capacity and transfer factor), additional precision is secured by adding to the regression equation on stature a term for fat-free mass or body mass divided by the square of the stature; for the description of functional residual capacity, the inclusion of a term for % body fat similarly reduces the variance about the regression equation. The difference in lung function between boys and girls is smaller when the function is related to stature than to sitting height. It is further reduced when fat-free mass/sature and % body fat are also included in the prediction equations. The equations may be used to obtain reference values for indices of lung function in similar subjects.

Adipose Tissue

Causal relationships between modifiable risk factors and heart failure: A comprehensive Mendelian randomization study.

Heart failure threatens human health across the globe. Comprehensively identifying its risk factors has public health importance. This work utilized the Mendelian randomization (MR) method to evaluate the effects of over 200 modifiable factors on heart failure. The data from genome-wide association studies (GWAS) was used, with the sample size ranging from 711 to 1232,091. Two distinct GWAS datasets for heart failure were employed for results validation. The inverse variance weighted (IVW) method was used and other supplementary models were employed for comparison. Sensitivity analysis was conducted to verify the results. After integrating the MR estimates derived from heart failure GWAS datasets from integrative epidemiology unit (IEU) and Finngen, we found that body measurement indices like body mass index, whole body fat mass, trunk fat mass, basal metabolic rate, body fat percentage, waist circumference, and waist-hip ratio, were associated with a higher risk of heart failure. Similarly, smoking behavior, sedentary behavior, overall health rating, and type 2 diabetes were determined to increase the risk of heart failure. In contrast, college or university degree showed a protective effect on heart failure. Among these significant findings, body mass index, whole body fat mass, trunk fat mass, basal metabolic rate, body fat percentage, overall health rating, smoking initiation, waist circumference, lifetime smoking index, college or university degree, sedentary behavior, waist-hip ratio, and type 2 diabetes were replicated validated. This MR work figured out that obesity, socioeconomic factors, lifestyle factors, and metabolic features showed broad relations with heart failure. The findings would provide evidence for future policy development for the management of heart failure.

Humans

Influence of muscular development, obesity, and age on the fat-free mass of adults.

Body fat and the fat-free mass (FFM) were estimated in 36 men and 43 women deliberately chosen to represent a variety of physical types; these were 1) young sedentary, 2) "muscular," 3) younger obese, 4) older obese, and 5) older nonobese individuals of both sexes. The body fat and the FFM were estimated from measurements of body density (by total immersion in water, measurement being made of the residual volume of air present in the lungs at immersion) and from measurements of total body potassium (using a whole-body monitor to assess the natural 40K isotope present in the body). The muscular men and women and the younger obese men and women had a considerably greater FFM and thus had greater quantities of potassium than the corresponding sedentary groups. There were significantly different estimates of the FFM calculated from density and from total body K in three groups, the sedentary young men, the muscular, and the younger obese women. The density and the potassium content of the FFM appear to decline with obesity and aging. Muscular development is associated with a decrease in the density but an increase in the potassium content of the FFM.

Adipose Tissue

Physiologic regulation of body energy storage.

Both new and published data (rats, mice, and human beings) on three parameters--fat mass, fat-free body mass (FFBM), and total body mass in some cases--are evaluated. Steady state values of the parameters are analyzed for changes in response to specific perturbing agents and for their frequency distributions. Temporal sequences of values on individuals are examined for evidence of regulatory responses. The results lead to the hypothesis that the FFBM is regulated, but probably not as a unit, and that mass of fat is regulated with a high priority near the range extremes but with a much lower priority in the mid-range. Properties and advantages of such a mechanism are discussed.

Adipose Tissue

Causal Relationships Between Modifiable Risk Factors and Gastroesophageal Reflux Disease: A Two-Sample Mendelian Randomization Study.

INTRODUCTION: Gastroesophageal reflux disease (GERD) is a prevalent digestive disorder, yet the causal roles of modifiable risk factors remain unclear. This study aims to investigate the causal relationships between 28 modifiable risk factors (including obesity traits, mental health disorders, sleep traits, metabolic comorbidities, and serum parameters) and GERD using two-sample Mendelian randomization (MR). Gastroesophageal reflux disease (GERD). Our findings aim to inform targeted prevention and treatment strategies for GERD. METHODS: This study obtained data from extensive genome-wide association studies (GWAS). Pooled data associated with gastroesophageal reflux associations were obtained from the 23andMe Research team's research, which included a total of 129,080 cases of gastroesophageal reflux and 473,524 controls of European ancestry. We conducted a univariable Mendelian randomization (MR) analysis to ascertain whether genetic evidence of exposure demonstrated a statistically significant association with the risk of GERD. Subsequently, a multivariable MR analysis was carried out to estimate the independent effects of the exposures on GERD. RESULTS: Univariable MR analysis utilizing extensive GWAS data suggested that genetic factors such as BMI, Waist circumference, Arm fat mass (left and right), Leg fat mass (left and right), Attention Deficit and Hyperactivity Disorder (ADHD), Major Depressive Disorder (MDD), Schizophrenia, Negative emotions (including nervousness, anxiety, tension, or depression), Insomnia, Sleep apnea syndrome, Sleep duration, and Snoring, as well as Total cholesterol levels and Apolipoprotein B levels, are associated with the development of GERD. Multivariate Mendelian randomization of BMI and Negative emotion as correction factors showed that Waist circumference, Arm fat mass (left and right), Leg fat mass (left and right), ADHD, Insomnia, Sleep apnea syndrome, and Snoring were associated with an increased risk of GERD (p< 0.05). Conversely, longer sleep duration was associated with a reduced risk of GERD (p< 0.05). DISCUSSION: This MR study reveals novel causal mechanisms in GERD pathogenesis: (1) Peripheral adiposity (arm/leg fat mass) exerts independent effects beyond central obesity, indicating site-specific fat distribution significance; (2) ADHD emerges as a distinct psychiatric risk factor independent of mental disorders; (3) Sleep apnea operates through BMI-independent pathways. Collectively, these findings redefine GERD pathophysiology, highlighting fat depot specificity and brain-gut interactions as critical mechanistic drivers. CONCLUSION: Overall, our findings suggest that multiple risk factors are associated with the risk of GERD. These results provide a theoretical basis for controlling body weight and plasticity, improving sleep habits, and preventing and timely seeking medical attention to reduce the occurrence of psychiatric disorders, which will be important strategies to prevent and alleviate GERD.

Humans

Estimating fat body mass from antrhopometric data.

Regression equations have been derived for the calculation of fat body mass in boys from 4 to 12 1/2 years old and girls 4 to 19 years old. Height and weight give a good prediction of fat body mass, but the addition of skinfold thicknesses to the regression equations reduces the number of large errors in the estimates. The regression equations and the limits of accuracy are given.

Adipose Tissue

Estimations of body composition by various methods.

Body composition was measured in 38 young men all of whom were overweight by standard height-weight tables. The techniques used were body volumetry, determination of total body water by tritium dilution, whole body 40K counting, and anthropometric measurements required for an equation by Wright and Wilmore, the biceps-height formula, and a complex anthropometric model. Body volumeter and total body water dilution results agreed closely. 40K counts gave lower means for the lean mass (higher means for fat mass and percent body fat), while the Wright-Wilmore equation and complex anthropometric model gave high mean values for lean mass (low means for fat mass and percent body fat). Among the five methods correlation coefficients ranged from 0.81 to 0.94 for lean body mass, from 0.74 to 0.89 for fat mass, and from 0.60 to 0.86 for percent body fat. Although all subjects were overweight, only six (16%) were obese.

Anthropometry

Body water compartments with human aging using fat-free mass as the reference standard.

Forty-five healthy men and women aged 16-39 and 59-89 yr were studied for total body water (TBW) and extracellular water (ECW); intracellular water (ICW) was calculated as the difference (ICW = TBW - ECW). An independent measurement of total body fat by inert gas uptake provided a value (+/- 2%) for fat-free mass (FFB is wt minus body fat). Results agreed with observations by others that TBW and ICW are lower in the aged and lower in women, whether expressed as absolute volumes or per unit of weight, surface area, or height. However, with FFB as the reference standard very different aging trends appeared. TBW/FFB remained constant to our oldest measured subjects (704 +/- 7 ml/kg). ICW/FFB was slightly lower at advanced age, but the 4-5% decrease for each sex was within statistical variability. With age ECW increased slightly and its proportion within the fat-free body (ECW/FFB) was significantly higher. Based upon FFB, the distribution, proportions, and aging trends of body water compartments were similar for men, women, and male rats. Although its potential limitations must be appreciated, the FFB appears widely useful as a reference standard. The stability of ICW volume and of fat-free mass in aging man does not support the hypothesis that cellular mass is lost by healthy mammals with age.

Adipose Tissue

Sex hormone concentrations in post-menopausal women.

Plasma sex hormone concentrations (testosterone, (T), androstenedione (A), oestrone (E1) and oestradiol (E2) were measured in forty post-menopausal women more than 4 years post-normal menopause. Correlations between these and age, years post-menopause (YPM), degree of obesity and fat mass respectively were studied. T and A, as well as E1 and E2 were positively correlated (P less than 0.01), but no statistically significant correlation between A and E1 was observed. Sex hormone concentrations in this group of postmenopausal women (greater than 4YPM) did not show any variation as a function of age, with the possible exception of E2 which showed a tendency to decrease in the late post-menopause. E1 and to a lesser extent E2 as well as the E1/A ratio were significantly corelated with degree of obesity or fat mass, suggesting a possible role of fat tissue in the aromatization of androgens. Neither the T/A nor the E2/E1 ratios were correlated with fat mass, suggesting that the reduction of 17 oxo-group does not occur in fat tissue. The E1/A ratio was significantly higher than the reported conversion rate of A in E1. This might suggest the existence of an additional precursor of plasma E1.

Age Factors

Sub maximal oxygen uptake related to fat free mass and lean leg volume in trained runners.

The sub maximal oxygen uptake (VO2) of 32 trained male middle and long distance runners aged 19.5-36.0 years was determined at five treadmill speeds. There was a significant linear relationship (p less than 0.01) between VO2 at each of the treadmill speeds and Fat-Free Mass (FFM) and Lean Leg Volume (LLV). To explain the relationship other factors are considered, the most important of which may be the mechanical configuration of muscle and mitochondrial function.

Adolescent

Growth and growth velocity of lean body mass and fat in adolescent boys.

Beginning at age 10 years, height, weight, body density, and bone age of 40 normal boys were measured yearly over a period of 8 years. From body density, lean body mass and body content of fat were calculated. Values for all measurements are included in the Appendix and mean values, including those for lean body mass and percentage of body fat, are presented for each year in Table 1. Coefficients of correlation between measurements made during the first and eighth years of study were high for height (0.68), weight (0.50), and lean body mass (0.60), but relatively low for body fat (0.25). Correlation coefficients between the various parameters in a given year are presented in Table 2. The maximum yearly increment in height, weight, and lean body mass of individual subjects coincided in time. The respective mean values for the year of maximum growth were 9.4 cm, 8.1 kg, and 7.5 kg. Throughout the growth spurt, the contribution of fat to increase in body weight was small. It may be concluded that, next to height, the absolute amount of lean body mass demonstrates the most constant trend of development during adolescence.

Adipose Tissue