Fat-free mass depletion in cystic fibrosis: Associated with lung disease severity but poorly detected by body mass index

ObjectiveMalnutrition in cystic fibrosis (CF) is associated with poorer survival, but the determinants of fat-free mass (FFM) depletion are not well-characterized. It is unknown whether routine nutritional indicators, including body mass index (BMI), are adequate for detecting FFM depletion. This study aimed to determine the prevalence of FFM depletion in adults with CF, to compare fat-free mass index (FFMI) with BMI, and to identify predictors of FFM depletion.MethodsThis was a prospective cross-sectional study of 86 adults with CF (19–59 y old). Body composition was assessed using dual-energy X-ray absorptiometry to determine FFMI and BMI. FFMI percentiles and Z-scores were derived from a reference population of 156 healthy adults. FFM depletion was defined as an FFMI below the fifth percentile for age and gender and low BMI as <18.5 kg/m². Univariate and multivariate analyses identified predictors of FFMI and FFMI Z-score.ResultsMean FFMIs were 18.3 ± 1.9 kg/m² in men with CF and 15.8 ± 1.1 kg/m² in women with CF (P < 0.0005). FFM depletion was found in 14% of adults with CF, and low BMI was found in 18.6%. The sensitivity of BMI for detecting FFM depletion was 42%. Forced expiratory volume in 1 s as a percentage of predicted was independently associated with FFMI in women (r = 0.62, P < 0.0001) and men (r = 0.28, P = 0.045) and FFMI Z-score (r = 0.41, P < 0.0001).ConclusionFFM depletion was found in 14% of adults with CF, but was undetectable by BMI in 58% of these patients. These findings, together with the association of FFMI with forced expiratory volume in 1 s predicted, suggest a role for body composition assessment in adult CF care.     

Oral Nutritional Supplements in Adults with Cystic Fibrosis: Effects on Intake,Levels of Fat-Soluble Vitamins,and Bone Remodeling Biomarkers

Background: The use of oral nutritional supplements (ONS) is common practice in patients suffering from cystic fibrosis (CF). We aimed to describe the rate of ONS use to assess their contribution to dietary intake and to determine if they are associated with respiratory status, body composition, muscle strength, bone mineral density (BMD), bone remodeling biomarkers, and plasmatic levels of vitamins. Methods: Cross-sectional study. Patients were clinically stable adults recruited from the CF unit. A 4-day prospective dietary questionnaire was conducted; in addition to respiratory variables, body composition, and BMD (through densitometry, DXA), muscle strength (JAMAR dynamometer), fat-soluble vitamins, and bone remodeling biomarkers (vitamins A, D, and E; osteocalcin, OC; undercarboxylated osteocalcin, ucOC; degradation of the C-terminal telopeptides of type I collagen, CTX; and receptor activator of nuclear factor-kappaB ligand, RANKL) were also evaluated. Results: The study included 59 subjects with CF (57.6% female, mean age 29.3 ± 9.4 years, and BMI 22.0 ± 3.6 kg/m²). In this study, 22% (13) patients were taking ONS and presented, compared with those not taking them, significantly more total and mild exacerbations and lower BMI; moreover, they showed a significantly higher total daily calorie intake in addition to a higher consumption of carbohydrates, proteins, and lipids per kg of body weight, omega-3 fatty acids, and vitamins A, D, and E. Vitamin E plasmatic levels were significantly higher in the group on ONS, as was the case with RANKL; finally, a lower rate of vitamin D deficiency was also found. Conclusions: ONS were used by patients with worse respiratory and nutritional statuses and their use was associated with a higher intake of macro- and micronutrients and with better plasmatic levels of fat-soluble vitamins.     

Evaluation of Nutritional Status and Methods to Identify Nutritional Risk in Rheumatoid Arthritis and Spondyloarthritis

Patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA) experience several nutritional challenges and are prone to develop malnutrition. This observational study aimed to perform a comprehensive nutritional assessment of outpatients diagnosed with RA and SpA, as well as to evaluate methods to identify nutritional risk. Nutritional status was investigated by anthropometric measures, body composition (DXA, dual energy X-ray absorptiometry), and handgrip strength (HGS). Nutritional risk was classified by Nutritional Risk Screening 2002 (NRS2002) and malnutrition was defined by the Global Leadership Initiative on Malnutrition (GLIM) criteria and fat-free mass index (FFMI; kg/m², <16.7 (M), <14.6 (F)). Out of 71 included patients, 46 (66%) were abdominally obese, 28 (39%) were obese in terms of body mass index (BMI), and 33 (52%) were obese in terms of the fat mass index (FMI; kg/m², ≥8.3 (M), ≥11.8 (F)). Malnutrition was identified according to FFMI in 12 (19%) patients, according to GLIM criteria in 5 (8%) patients, and on the basis of BMI (<18.5 kg/m²) in 1 (1%) patient. None were identified by NRS2002 to be at nutritional risk. Our study revealed high prevalence of abdominal obesity and low FFMI. Waist circumference was a good indicator of FMI. BMI, NRS2002, and HGS did not capture patients with malnutrition identified by DXA.     

Muscular Ultrasonography in Morphofunctional Assessment of Patients with Oncological Pathology at Risk of Malnutrition

Background: Muscular ultrasonography is a technique that allows assessing the amount and quality of muscle in a specific body region. The aim of the study was to compare the value of muscle ultrasonography in diagnosis of malnutrition with techniques such as anthropometry, handgrip strength and impedanciometry in patients with oncological pathology. Methods: Cross-sectional study in 43 patients with oncological pathology and high nutritional risk. Classical anthropometry (body mass index (BMI), arm circumference (AC), calf circumference (CC) and estimated appendicular muscle mass index (ASMI)) was performed. Body composition was measured with impedanciometry (BIA), phase angle (PA) and fat-free mass index (FFMI) and muscle ultrasonography of quadriceps rectus femoris (muscle area (MARA) and circumference (MCR) in section transverse). Malnutrition was diagnosed using the GLIM criteria and sarcopenia was assessed using EWGSOP2 criteria. Results: The mean age was 68.26 years (±11.88 years). In total, 23/20 of the patients were men/women. The BMI was 23.51 (4.75) kg/m². The ASMI was 6.40 (1.86) kg/m². The MARA was 3.31 cm² in ultrasonography. In impedanciometry, phase angle was 4.91 (0.75)°; the FFMI was 17.01 kg/m² (±2.65 kg/m²). A positive correlation was observed between the MARA with anthropometric measurements (AC: r = 0.39, p = 0.009; CC: r = 0.44, p < 0.01; ASMI: r = 0.47, p < 0.001); and with BIA (FFMI: r = 0.48, p < 0.01 and PA: r = 0.45, p < 0.001). Differences were observed when comparing the MARA based on the diagnosis of sarcopenia (Sarcopenia: 2.47 cm² (±0.54 cm²); no sarcopenia: 3.65 cm² (±1.34 cm²); p = 0.02). Conclusions: Muscle ultrasonography correlates with body composition measurement techniques such as BIA and anthropometry in patients with cancer.     

Body composition interpretation. Contributions of the fat-free mass index and the body fat mass index

OBJECTIVE: Low and high body mass index (BMI) values have been shown to increase health risks and mortality and result in variations in fat-free mass (FFM) and body fat mass (BF). Currently, there are no published ranges for a fat-free mass index (FFMI; kg/m(2)), a body fat mass index (BFMI; kg/m(2)), and percentage of body fat (%BF). The purpose of this population study was to determine predicted FFMI and BFMI values in subjects with low, normal, overweight, and obese BMI. METHODS: FFM and BF were determined in 2986 healthy white men and 2649 white women, age 15 to 98 y, by a previously validated 50-kHz bioelectrical impedance analysis equation. FFMI, BFMI, and %BF were calculated. RESULTS: FFMI values were 16.7 to 19.8 kg/m(2) for men and 14.6 to 16.8 kg/m(2) for women within the normal BMI ranges. BFMI values were 1.8 to 5.2 kg/m(2) for men and 3.9 to 8.2 kg/m(2) for women within the normal BMI ranges. BFMI values were 8.3 and 11.8 kg/m(2) in men and women, respectively, for obese BMI (>30 kg/m(2)). Normal ranges for %BF were 13.4 to 21.7 and 24.6 to 33.2 for men and women, respectively. CONCLUSION: BMI alone cannot provide information about the respective contribution of FFM or fat mass to body weight. This study presents FFMI and BFMI values that correspond to low, normal, overweight, and obese BMIs. FFMI and BFMI provide information about body compartments, regardless of height.     

New Reference Values for Body Composition by Bioelectrical Impedance Analysis in the General Population: Results From the UK Biobank

BackgroundLow fat-free mass (FFM) is a risk factor for morbidity and mortality in elderly and patient populations. Therefore, measurement of FFM is important in nutritional assessment. Bioelectrical impedance analysis (BIA) is a convenient method to assess FFM and FFM index (FFMI; FFM/height²). Although reference values have been established for individuals with normal body weight, no specific cutoff values are available for overweight and obese populations. Also, limited studies accounted for the age-related decline in FFM.ObjectiveTo determine BMI- and age-specific reference values for abnormal low FFM(I) in white-ethnic men and women free of self-reported disease from the general population.DesignThe UK Biobank is a prospective epidemiological study of the general population from the United Kingdom. Individuals in the age category 45 to 69 years were analyzed. In addition to body weight, FFM and FFMI were measured using a Tanita BC-418MA. Also, self-reported chronic conditions and ethnic background were registered, and lung function was assessed using spirometry.ResultsAfter exclusion of all individuals with missing data, nonwhite ethnicity, self-reported disease, body mass index (BMI) less than 14 or 36 kg/m² or higher, and/or an obstructive lung function, reference values for FFM and FFMI were derived from 186,975 individuals (45.9% men; age: 56.9 ± 6.8 years; BMI: 26.5 ± 3.6 kg/m²; FFMI 18.3 ± 2.4 kg/m²). FFM and FFMI were significantly associated with BMI and decreased with age. Percentiles 5, 10, 25, 50, 75, 90, and 95 were calculated for FFM, FFMI, and fat mass (index), after stratification for gender, age, and BMI.ConclusionsUsing the UK Biobank dataset, new reference values for body composition assessed with BIA were determined in white-ethnic men and women aged 45 to 69 years. Because these reference values are BMI specific, they are of broad interest for overweight and obese populations.     

Dietary Protein Requirement Threshold and Micronutrients Profile in Healthy Older Women Based on Relative Skeletal Muscle Mass

Although multiple nutrients have shown protective effects with regard to preserving muscle function, the recommended amount of dietary protein and other nutrients profile on older adults for maintenance of high muscle mass is still debatable. The aims of this paper were to: (1) identify dietary differences between older women with low and high relative skeletal muscle mass, and (2) identify the minimal dietary protein intake associated with high relative skeletal muscle mass and test the threshold ability to determine an association with skeletal muscle phenotypes. Older women (n = 281; 70 ± 7 years, 65 ± 14 kg), with both low and high relative skeletal muscle mass groups, completed a food questionnaire. Skeletal muscle mass, fat-free mass (FFM), biceps brachii thickness, vastus lateralis anatomical cross-sectional area (VL_ACSA), handgrip strength (HGS), maximum elbow flexion torque (MVC_EF), maximum knee extension torque (MVC_KE), muscle quality (HGS/Body mass), and fat mass were measured. Older women with low relative skeletal muscle mass had a lower daily intake of protein, iodine, polyunsaturated fatty acid (PUFA), Vit E, manganese, milk, fish, nuts and seeds (p < 0.05) compared to women with high relative skeletal muscle mass. The minimum required dietary protein intake for high relative skeletal muscle mass was 1.17 g/kg body mass/day (g/kg/d) (sensitivity: 0.68; specificity: 0.62). Women consuming ≥1.17 g/kg/d had a lower BMI (B = −3.9, p < 0.001) and fat mass (B = −7.8, p < 0.001), and a higher muscle quality (B = 0.06, p < 0.001). The data indicate that to maintain muscle mass and function, older women should consume ≥1.17 g/kg/d dietary protein, through a varied diet including milk, fish and nuts that also contain polyunsaturated fatty acid (PUFA) and micronutrients such as iodine, Vit E and manganese.     

Comparison of fat-free mass index and fat mass index in Chinese adults

Background/Objectives:To compare the characteristics of body composition for different gender and age in a large number of apparently healthy Chinese subjects, and to determine reference values for fat-free mass index (FFMI) and fat mass index (FMI).Subjects/Methods:In total, 61?382 Chinese adults (age range: 18-92 years) were consecutively enrolled into the study. Body composition was measured using bioelectrical impedance analysis with a tetrapolar impedance meter.Results:The skeletal muscle mass, fat-free mass (FFM), FFMI and body mass index (BMI) were significantly higher in men than in women (P<0.05), but FM% and FMI were significantly higher in women (P<0.05). In the group with normal BMI (BMI 18.5-23.9?kg/m(2), 18-92?years), the reference values (5th-95th percentile) of FM%, FFMI and FMI were 9.7-34.5%, 14.15-19.76 and 1.99-7.75?kg/m(2) in men, and 18.1-35.8%, 13.82-17.89 and 3.68-8.16?kg/m(2) in women, respectively.Conclusions:Reference intervals for FFMI and FMI could be of practical value for the clinical evaluation of a deficit in FFM with or without excess FM for a given age category, complementing the classical concept of BMI in a more qualitative manner, although these indices are only suggestive indications for the degree of obesity. In contrast to BMI, similar reference ranges of FFMI seem to be more utilizable with advancing age.     

Association of Body Composition with Curve Severity in Children and Adolescents with Idiopathic Scoliosis (IS)

The link between scoliotic deformity and body composition assessed with bioimpedance (BIA) has not been well researched. The objective of this study was to correlate the extent of scoliotic-curve severity with the anthropometrical status of patients with idiopathic scoliosis (IS) based on standard anthropometric measurements and BIA. The study encompassed 279 IS patients (224 girls/55 boys), aged 14.21 ± 2.75 years. Scoliotic curve severity assessed by Cobb’s angle was categorized as moderate (10°–39°) or severe (≥40°). Corrected height, weight, waist and hip circumferences were measured and body mass index (BMI), corrected height z-score, BMI Z-score, waist/height ratio (WHtR) and waist/hip ratio (WHR) were calculated for the entire group. Body composition parameters: fat mass (FAT), fat-free mass (FFM) and predicted muscle mass (PMM) were determined using a bioelectrical impedance analyzer. The mean Cobb angle was 19.96° ± 7.92° in the moderate group and 52.36° ± 12.54° in the severe group. The corrected body heights, body weights and BMIs were significantly higher in the severe IS group than in the moderate group (p < 0.05). Significantly higher FAT and lower FFM and PMM were observed in the severe IS group (p < 0.05). The corrected heights and weights were significantly higher in patients with severe IS and normal weight (p < 0.01). Normal and overweight patients with a severe IS had significantly higher adiposity levels assessed by FAT, FFM and PMM for normal and BMI, BMI z-score, WHtR, FAT and PMM for overweight, respectively. Overweight IS patients were significantly younger and taller than underweight and normal weight patients. The scoliotic curve severity is significantly related to the degree of adiposity in IS patients. BMI z-score, WHtR and BIA seem to be useful tools for determining baseline anthropometric characteristics of IS children.     

BMI and morbidity in relation to body composition: a cross-sectional study of a rural community in North-East India

This paper deals with BMI and morbidity in relation to body-fat mass (BFM) and fat-free mass (FFM). The analysis was based on cross-sectional data concerning the age, household income, anthropometry and morbidity of 575 males aged 18-59 years from a rural community in North-East India. Data on morbidity were based on the self-reported morbidity (SRM) of the subjects during the last 4 weeks before the survey, whereas data on BMI and body composition were estimated from anthropometry. It was found that SRM was significantly associated with age and income. However, the relationship between BMI and SRM was not significant after adjusting for age and income. Separating the BMI into body-fat mass index (BFMI being BFM in kg divided by height squared in metres) and fat-free mass index (FFMI being FFM in kg divided by height squared in metres), it was found that BFMI was significantly associated with SRM after adjusting for age, income and FFMI. The subjects with a low (<2.9 kg/m(2)) BFMI were about 4.7 times (odds ratio 4.7, 95 % CI 2.6, 8.6) more likely to become sick than those with a normal (2.9-5.0 kg/m(2)) BFMI. In addition, the risk of becoming sick was higher in the subjects with a high (>5.0 kg/m(2)) BFMI than in those with a normal BFMI (odds ratio 3.9, 95 % CI 1.3, 9.8). However, the relationship between FFMI and morbidity was not clearly perceptible. It is therefore speculated that BMI may not always provide accurate information about the variation in body fat and body composition that is associated with morbidity.     

Fat-Free Mass Index as a Surrogate Marker of Appendicular Skeletal Muscle Mass Index for Low Muscle Mass Screening in Sarcopenia

ObjectivesWe aimed to examine the relationship between the fat-free mass index (FFMI; FFM/height²) and appendicular skeletal muscle mass index (ASMI; ASM/height²), measured using both bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA), and investigate the effects of age and obesity. We also evaluated the suitability of BIA-measured FFMI as a simple surrogate marker of the ASMI and calculated the optimal FFMI cutoff value for low muscle mass screening to diagnose sarcopenia.DesignCross-sectional study.Setting and ParticipantsThis study included 1313 adults (women, 33.6%) aged 40-87 years (mean age, 55 ± 10 years) from the WASEDA’S Health Study.MethodsBody composition was measured using multifrequency BIA and DXA. Low muscle mass was defined according to the criteria of the Asian Working Group for Sarcopenia 2019.ResultsBIA-measured FFMI showed strong positive correlations with both BIA- (r = 0.96) and DXA-measured (r = 0.95) ASMIs. Similarly, in the subgroup analysis according to age and obesity, the FFMI was correlated with the ASMI. The areas under the receiver operating characteristic curve for screening low muscle mass defined by DXA-measured ASMI using BIA-measured FFMI values were 0.95 (95% CI 0.93-0.97) for men and 0.91 (95% CI 0.87-0.94) for women. The optimal BIA-measured FFMI cutoff values for screening low muscle mass defined by DXA-measured ASMI were 17.5 kg/m² (sensitivity 89%, specificity 88%) for men and 14.6 kg/m² (sensitivity 80%, specificity 86%) for women.Conclusions and ImplicationsThe FFMI showed a strong positive correlation with BIA- and DXA-measured ASMIs, regardless of age and obesity. The FFMI could be a useful simple surrogate marker of the ASMI for low muscle mass screening in sarcopenia in community settings. The suggested FFMI cutoff values for predicting low muscle mass are <18 kg/m² in men and <15 kg/m² in women.     

Creatine Enhances the Effects of Cluster-Set Resistance Training on Lower-Limb Body Composition and Strength in Resistance-Trained Men: A Pilot Study

Creatine monohydrate (CrM) supplementation has been shown to improve body composition and muscle strength when combined with resistance training (RT); however, no study has evaluated the combination of this nutritional strategy with cluster-set resistance training (CS-RT). The purpose of this pilot study was to evaluate the effects of CrM supplementation during a high-protein diet and a CS-RT program on lower-limb fat-free mass (LL-FFM) and muscular strength. Twenty-three resistance-trained men (>2 years of training experience, 26.6 ± 8.1 years, 176.3 ± 6.8 cm, 75.6 ± 8.9 kg) participated in this study. Subjects were randomly allocated to a CS-RT+CrM (n = 8), a CS-RT (n = 8), or a control group (n = 7). The CS-RT+CrM group followed a CrM supplementation protocol with 0.1 g·kg⁻¹·day⁻¹ over eight weeks. Two sessions per week of lower-limb CS-RT were performed. LL-FFM corrected for fat-free adipose tissue (dual-energy X-ray absorptiometry) and muscle strength (back squat 1 repetition maximum (SQ-1RM) and countermovement jump (CMJ)) were measured pre- and post-intervention. Significant improvements were found in whole-body fat mass, fat percentage, LL-fat mass, LL-FFM, and SQ-1RM in the CS-RT+CrM and CS-RT groups; however, larger effect sizes were obtained in the CS-RT+CrM group regarding whole body FFM (0.64 versus 0.16), lower-limb FFM (0.62 versus 0.18), and SQ-1RM (1.23 versus 0.75) when compared to the CS-RT group. CMJ showed a significant improvement in the CS-RT+CrM group with no significant changes in CS-RT or control groups. No significant differences were found between groups. Eight weeks of CrM supplementation plus a high-protein diet during a CS-RT program has a higher clinical meaningfulness on lower-limb body composition and strength-related variables in trained males than CS-RT alone. Further research might study the potential health and therapeutic effects of this nutrition and exercise strategy.     

Association of Cesarean Delivery with Trajectories of Growth and Body Composition in Preschool Children

This study aimed to examine the association of cesarean delivery with trajectories of growth and body composition in preschool children. This ambidirectional cohort study was conducted between 2017 and 2020 in China. Information on the delivery mode, weight, and length/height of the children measured at routine healthcare visits was obtained from maternal and child health records. For three years while in kindergarten, children’s body mass index (BMI), fat mass index (FMI), fat-free mass index (FFMI), and percentage of body fat (FM%) were repeatedly measured. A BMI z score (zBMI) was calculated and standardized to WHO measures, and overweight and obesity were defined using the WHO reference. After adjustment for maternal age, maternal education, annual family income, prepregnancy BMI, gestational weight gain, gravidity, parity, gestational age, child sex, birthweight, breastfeeding duration, and the parent-reported dietary intake of the children, children born via cesarean delivery (n = 1992) versus those born vaginally (n = 1578) had higher zBMI growth rates beyond 36 months (β: 0.003; 95% CI: 0.001, 0.005 SD units/month) and elevated levels of FMI (β: 0.097; 95% CI: 0.026, 0.168 kg/m²), FM% (β: 0.402; 95% CI: 0.058, 0.745%) and zBMI (β: 0.073; 95% CI: 0.012, 0.133 units), but not FFMI (β: 0.022; 95% CI: −0.022, 0.066 kg/m²). The adjusted OR of overweight and obesity was 1.21 (95% CI: 1.04, 1.40). Cesarean delivery likely elevated zBMI growth rates and increased the risk of overweight and obesity in preschool children, with the elevation of fat mass but not fat-free mass.     

An Increase in Fat-Free Mass is Associated with Higher Appetite and Energy Intake in Older Adults: A Randomised Control Trial

Cross-sectional studies in younger adults have demonstrated a positive association between energy intake (EI) and fat-free mass (FFM), with this relationship seemingly mediated by resting metabolic rate (RMR). Establishing a causal effect longitudinally would be prudent in older adults suffering from loss of appetite. We investigated the effects of FFM on RMR, appetite and EI in 39 healthy older adults (age: 66 ± 4 years, BMI: 25.1 ± 3.5 kg∙m²) assigned to either 12-week resistance training + protein supplementation group (RT + PRO) or control group (CON). Body composition, subjective appetite, leptin, insulin, RMR and laboratory-measured ad libitum EI were measured at baseline, weeks 6 and 12 of the intervention, while daily EI at baseline and week 12. FFM (+1.2 kg; p = 0.002), postprandial subjective appetite (+8 mm; p = 0.027), ad libitum EI (+119 kcal; p = 0.012) and daily EI (+133 kcal; p = 0.010) increased from baseline to week 12 in the RT + PRO. RMR, fasted subjective appetite, leptin and insulin concentrations remained unchanged (all p > 0.05). The increases ad libitum EI correlated with increases in FFM (r = 0.527, p = 0.001), with 54% of the change in EI attributed to FFM changes. In conclusion, FFM increases were associated with an increased ad libitum EI and postprandial appetite in older adults.     

Magnesium Intake,C-Reactive Protein,and Muscle Mass in Adolescents

Background: Adult studies have suggested that magnesium intake may regulate C-reactive protein (CRP) and muscle mass, known risk factors for cardiometabolic diseases. Given the large deficiencies in magnesium intake in adolescents, we aimed to investigate sex and race differences in dietary magnesium intake and test the hypothesis that lower magnesium intake is associated with higher CRP and lower muscle mass. Methods: A total of 766 black and white adolescents, 14 to 18 years old (51% black; 50% female) were previously recruited. Diet was assessed with four to seven independent 24-h recalls. Body composition was measured by dual-energy X-ray absorptiometry. High-sensitivity CRP (hs-CRP), leptin, resistin, and adiponectin were measured using fasting blood samples by ELISA. Results: There were sex and race differences in the daily consumption of magnesium. The average daily magnesium intakes were 200.66 ± 7.09 mg and 205.03 ± 7.05 mg for males and females, respectively, far below the recommended amounts of 410 mg for males and 360 mg for females. White subjects (217.95 ± 6.81 mg/day) consumed more than black subjects (187.75 ± 6.92 mg/day). Almost none of the adolescents met the recommendations. Adjusted multiple linear regressions revealed that lower magnesium intake was associated with higher hs-CRP and lower fat-free mass (FFM) (p-values < 0.05). Higher hs-CRP was associated with lower FFM. Moreover, an interaction between magnesium intake and hs-CRP on FFM was identified (p-value < 0.05). Lower magnesium intake amplified the inverse relationships between hs-CRP and FFM (p-values < 0.05). Conclusion: Magnesium consumption in our adolescents was far below daily recommended levels with male and black subjects consuming less than female and white subjects. Lower magnesium intake was associated with higher CRP and lower muscle mass. Low magnesium intake may also augment the inverse relationship between CRP and FFM.     

儿童青少年身体成分与身体素质的关系

  目的  了解儿童青少年体脂率(FM%)、体脂指数(FMI)、去脂体质量指数(FFMI)和体质量指数(BMI)与身体素质的关联性,为探讨身体成分指标对儿童青少年体育锻炼程度的潜在价值提供参考。  方法  数据来源于2013年教育部国家学生体质健康标准修订北京地区样本,采用Inbody 230对北京市4 069名6~20岁儿童青少年进行身体成分测定,用四分位数法将FM%、FMI、FFMI和BMI分别分成4组,用GraphPad Prism 8.0软件对4组的体测成绩进行差异性分析。  结果  男生FM%(20.03±10.39)和FMI[(4.35±2.84)kg/m2]均小于女生,而FFMI[(14.21±4.95)kg/m2]和BMI[(20.31±4.27)kg/m2]均大于女生(t值分别为-13.36,-7.66,11.49,8.16,P值均 < 0.01)。在男生中随着FM%和FMI增加,50 m跑、1 000 m跑、立定跳远和引体向上的成绩呈下降趋势; 随着FFMI增加,50 m跑、立定跳远和引体向上成绩有上升趋势。在女生中,随着FM%和FMI增加,50 m跑时间逐渐缩短,800 m跑时间逐渐增长;FFMI越大50 m跑时间呈现出下降趋势,而在800 m跑中未见FFMI的显著趋势性。4个体成分指标对于坐位体前屈和1 min仰卧起坐无明显预测作用。  结论  FM%、FMI、FFMI和BMI对于儿童青少年身体素质有很好的预测作用。FFMI较高、FM%和FMI较低者在肌肉爆发力、肌肉耐力、柔韧性、有氧能力、无氧能力方面有更好表现,且这种趋势在男生中更为明显。     

Body composition in early onset eating disorders

BACKGROUND: Body mass index (BMI) or equivalent weight for height indices are the most widely used measures of body composition in early onset and adolescent eating disorders. Although of value as screening instruments the limitation in disease states is their inability to discriminate fat and fat-free components of body weight. OBJECTIVE: To compare height-adjusted fat and fat-free components of body composition in children and young adolescents with different types of eating disorders with those of age matched reference children. DESIGN: Weight, height, triceps and subscapular skinfold thickness were measured in 172 children (aged 7-16 y) with eating disorders receiving specialist treatment. Fat mass index (FMI) and fat-free mass index (FFMI) were calculated using Slaughter's and Deurenberg's equations and normalisation for height. Using data from 157 normal children, representative of the UK 1990 growth reference data, reference curves for FMI and FFMI+/-2 s.d. were derived. Results for patient groups were superimposed on these reference curves. RESULTS: FMI and FFMI were both reduced in eating disorders associated with malnutrition, including anorexia nervosa (AN). AN subjects did not differ from other subjects with comparable degrees of malnutrition. Children with eating disorders of normal weight, such as bulimia nervosa and selective eating, did not differ significantly from reference children in their relative FM and FFM. CONCLUSIONS: FM and FFM merit independent consideration in disorders of malnutrition in children, rather than expressing data as percentage body fat or percentage BMI. The implications of loss of FFM on growth and development merit further investigation.     

Low Energy Availability with and without a High-Protein Diet Suppresses Bone Formation and Increases Bone Resorption in Men: A Randomized Controlled Pilot Study

Suppression of insulin-like growth factor 1 (IGF-1) and leptin secondary to low energy availability (LEA) may contribute to adverse effects on bone health. Whether a high-protein diet attenuates these effects has not been tested. Seven men completed three five-day conditions operationally defined as LEA (15 kcal kg fat-free mass (FFM)⁻¹·day⁻¹) with low protein (LEA-LP; 0.8 g protein·kg body weight (BW)⁻¹), LEA with high protein (LEA-HP; 1.7 g protein·kg BW⁻¹) and control (CON; 40 kcal·kg FFM⁻¹·day⁻¹, 1.7 g protein·kg BW⁻¹). In all conditions, participants expended 15 kcal·kg FFM⁻¹·day⁻¹ during supervised cycling sessions. Serum samples were analyzed for markers of bone turnover, IGF-1 and leptin. The decrease in leptin during LEA-LP (−65.6 ± 4.3%) and LEA-HP (−54.3 ± 16.7%) was greater than during CON (−25.4 ± 11.4%; p = 0.02). Decreases in P1NP (p = 0.04) and increases in CTX-I (p = 0.04) were greater in LEA than in CON, suggesting that LEA shifted bone turnover in favour of bone resorption. No differences were found between LEA-LP and LEA-HP. Thus, five days of LEA disrupted bone turnover, but these changes were not attenuated by a high-protein diet.     

Body mass index, body composition and the chronic energy deficiency classification of rural adult populations in Guatemala.

The present study tested the hypotheses that: (a) individual body composition estimates obtained with the Durnin-Womersley (D-W) equations have low validity in certain populations in developing countries; (b) there exists a poor relationship between the body mass index (BMI) and body composition estimates (fat mass (BFM) and fat-free mass (FFM)), and (c) BMI cut-off estimates (fat mass (BFM) and fat-free mass (FFM)), and (c) BMI cut-off points provide an invalid classification of chronic energy deficiency (CED) in adults. The study involved four samples of rural men and women in Guatemala, who had mean BMI of approximately 21 kg/m2. Body composition estimates were obtained by densitometry in three of the samples. Mean body fat (%) and mean FFM (kg) were: men: 11.6 (+/- 4.7) and 47.7 (+/- 4.9); and women: 21.6 (+/- 5.3) and 35.8 (+/- 3.5), respectively. The D-W equations based on various combinations of skinfold measurements consistently overestimated body fat content with low precision and validity. The BMI was more related to BFM and FFM than to fat proportion, but explained little of the variation in both body components, particularly at low BMI levels. A small number of men and women had BMI values below 18.5 kg/m2, and only one woman fell below 16 kg/m2. The power coefficients of height in the weight/height ratio which provided the strongest correlations with BFM and FFM were: BFM: women: 1.0; men: 1.5; FFM: 0.5 for both women and men. We conclude that the Quetelet index should not be recommended as a universally valid indicator to classify CED in adult groups similar to the study population.     

Relation of body composition to daily physical activity in free-living Japanese adult women

The objective of the present study was to investigate the relationship between the indices of body size such as BMI, fat-free mass index (FFMI, FFM/height2), fat mass index (FMI, FM/height2), and body fat percentage (%BF), and physical activities assessed by the doubly-labelled water (DLW) method and an accelerometer in free-living Japanese adult women. We conducted a cross-sectional study in 100 female subjects ranging in age from 31 to 69 years. Subjects were classified in quartiles of BMI, FFMI, FMI and %BF. Daily walking steps and the duration of light to vigorous physical activity were simultaneously assessed by an accelerometer for the same period as the DLW experiment. Only physical activity-related energy expenditure (PAEE)/FFM and PAEE/body weight (BW) decreased in the highest quartile of BMI. Physical activity level, PAEE/FFM and PAEE/BW decreased in the highest quartile of FMI and %BF, whereas they were not different among quartiles of FFMI. Daily walking steps and the duration of moderate- and vigorous-intensity physical activities decreased or tended to decrease in the highest quartile of FMI and %BF, but did not differ among quartiles of FFMI and BMI. These results clearly showed that Japanese adult women with higher fat deposition obviously had a low level of physical activities assessed by both the DLW method and accelerometry, but those with larger BMI had lower PAEE/FFM and PAEE/BW only. Our data suggest that the relationship between obesity and daily physical activities should be discussed using not only BMI but also FMI or %BF.