Sex Differences In Body Composition Research Articles

Exploring the role of sex in the association of late chronotype on cardiorespiratory fitness.

Circadian rhythms differ between young adult males and females. For example, males tend to be later chronotypes, preferring later timing of sleep and activity, than females. Likewise, there are sex differences in body composition and cardiorespiratory fitness. Few studies have investigated the association between circadian rhythms, cardiorespiratory fitness, and body composition. We sought to determine whether chronotype and circadian phase were associated with cardiorespiratory fitness, body composition, and anthropometric measures in sedentary males and females. Fifty-nine adults participated in the study. Circadian phase and chronotype were measured using dim light melatonin onset (DLMO) and the Morningness-Eveningness Questionnaire (MEQ) score. We used peak oxygen uptake (VO2peak ) results from a maximal graded exercise test to assess cardiorespiratory fitness. Body composition, BMI, and circumferences were collected as markers of adiposity. We observed a sex difference in the association between DLMO and VO2peak . For males, a later DLMO was associated with a lower VO2peak . VO2peak did not vary based on DLMO in females. Later circadian phase was also associated with increased body fat percentage, fat mass index, and abdominal circumference in males, but not females. Collectively, these results suggest that males who are later chronotypes may be at risk of obesity and low cardiorespiratory fitness.

Lifespan Effects of Muscle-Specific Androgen Receptor Overexpression on Body Composition of Male and Female Rats.

Androgenic actions of gonadal testosterone are thought to be a major mechanism promoting sex differences in body composition across the lifespan. However, this inference is based on studies of androgen receptor (AR) function in late adolescent or emerging adult rodents. Here we assess body composition and AR expression in skeletal muscle of rats at defined ages, comparing wild-type (WT) to transgenic human skeletal actin-driven AR overexpression (HSAAR) rats which overexpress AR in skeletal muscle. Male and female HSAAR and WT Sprague Dawley rats (N = 288) underwent dual-energy x-ray absorptiometry (DXA) scanning and tissue collection at postnatal day (PND) 1, 10, 21, 42, 70, 183, 243, and 365. Expected sex differences in body composition and muscle mass largely onset with puberty (PND-21), with no associated changes to skeletal muscle AR protein. In adulthood, HSAAR increased tibialis anterior (TA) and extensor digitorum longus mass in males, and reduced the expected gain in gonadal fat mass in both sexes. In WT rats, AR protein was reduced in soleus, but not TA, throughout life. Nonetheless, soleus AR protein expression was greater in male rats than female rats at all ages of sexual development, yet only at PND-70 in TA. Overall, despite muscle AR overexpression effects, results are inconsistent with major sex differences in body composition during sexual development being driven by changes in muscle AR, rather suggesting that changes in ligand promote sexual differentiation of body composition during pubertal timing. Nonetheless, increased skeletal muscle AR in adulthood can be sufficient to increase muscle mass in males, and reduce adipose in both sexes.

Sex Differences In Body Composition And Serum Metabolome Responses To Military Training

Sex Differences In Body Composition And Serum Metabolome Responses To Military Training

Is Height2.7 Appropriate for Indexation of Left Ventricular Mass in Healthy Adolescents? The Importance of Sex Differences.

Left ventricular mass (LVM) is an important predictor of cardiovascular risk. In adolescence, LVM is commonly indexed to height2.7, although some evidence suggests that this may not fully account for sex differences. We investigated appropriate allometric scaling of LVM to height, total lean mass, and body surface area, in a UK birth cohort of 2039 healthy adolescents (17±1 years). Allometric relationships were determined by linear regression stratified by sex, following log transformation of x and y variables [log(y)=a+b×log(x)], b is the allometric exponent. Log (LVM) showed linear relationships with log(height) and log(lean mass). Biased estimates of slope resulted when the sexes were pooled. The exponents were lower than the conventional estimate of 2.7 for males (mean [95% CI]=1.66 [1.30-2.03]) and females (1.58 [1.27-1.90]). When LVM was indexed to lean mass, the exponent was 1.16 (1.05-1.26) for males and 1.07 (0.97-1.16) for females. When LVM was indexed to estimated body surface area, the exponent was 1.53 (1.40-1.66) for males and 1.34 (1.24-1.45) for females. Allometric exponents derived from pooled data, including men and women without adjustment for sex were biased, possibly due to sex differences in body composition. We suggest that when assessing LVM, clinicians should consider body size, body composition, sex, and age. Our observations may also have implications for the identification of young individuals with cardiac hypertrophy.

Body composition in healthy singleton term infants using the three-dimensional photonic scanning method: A multicenter cross-sectional study

ObjectivesBody composition is an integral part of the nutritional assessment during infancy as it is closely related to future health. The three-dimensional photonic body surface scanning (3-DPS) method is a promising new technique for measuring body composition in children because of its advantages of easy operation, low cost, and no exposure to radiation. Using 3-DPS, this study aimed to illustrate the growth trajectories of body composition indicators during infancy according to sex and age. MethodsThis was a multicenter cross-sectional study. The body compositions of 9644 singleton term infants from four centers in Shandong Province, China, were assessed using 3-DPS. The data of 8769 healthy infants (52.0% boys), whose z scores of weight-for-length, length-for-age, and weight-for-age, according to World Health Organization standards, were in the range of –2 to 2, –3 to 3, and –3 to 3, respectively, were sampled to construct percentile curves of fat mass (FM), fat-free mass (FFM), FM percentage (FM%), FM index (FMI), and FFM index (FFMI) with the generalized additive model for location, scale, and shape method. ResultsPercentile charts for FM, FFM, FM%, FMI, and FFMI were developed based on age and sex. FM and FFM presented consistent trajectories with that of weight, with the fastest growth occurring at 1 to 3 mo of age. FM%, FMI, and FFMI increased with age, peaked at 6 mo, and gradually declined, which was consistent with the body mass index trend. All indicators, except for FFMI, were always significantly higher in boys than in girls ages 1 to 12 mo, indicating that sex differences in body composition existed mainly in FM rather than in lean body mass. ConclusionsThe body composition of healthy singleton term infants during infancy varies with age; boys may have more FM accumulation than girls.

Sex differences in body composition and serum metabolome responses to sustained, physical training suggest enhanced fat oxidation in women compared with men.

Sex differences in energy metabolism during acute, submaximal exercise are well documented. Whether these sex differences influence metabolic and physiological responses to sustained, physically demanding activities is not well characterized. This study aimed to identify sex differences within changes in the serum metabolome in relation to changes in body composition, physical performance, and circulating markers of endocrine and metabolic status during a 17-day military training exercise. Blood was collected, and body composition and lower body power were measured before and after the training on 72 cadets (18 women). Total daily energy expenditure (TDEE) was assessed using doubly labeled water in a subset throughout. TDEE was greater in men (4,085 ± 482 kcal/d) than in women (2,982 ± 472 kcal/d, P < 0.001), but not after adjustment for dry lean mass (DLM). Men tended to lose more DLM than women (mean change [95% CI]: -0.2[-0.3, -0.1] vs. -0.0[-0.0, 0.0] kg, P = 0.063, Cohen's d = 0.50) and have greater reductions in lower body power (-244[-314, -174] vs. -130[-209, -51] W, P = 0.085, d = 0.49). Reductions in DLM and lower body power were correlated (r = 0.325, P = 0.006). Women demonstrated greater fat oxidation than men (Δfat mass/DLM: -0.20[-0.24, -0.17] vs. -0.15[-0.17, -0.13] kg, P = 0.012, d = 0.64). Metabolites within pathways of fatty acid, endocannabinoid, lysophospholipid, phosphatidylcholine, phosphatidylethanolamine, and plasmalogen metabolism increased in women relative to men. Independent of sex, changes in metabolites related to lipid metabolism were inversely associated with changes in body mass and positively associated with changes in endocrine and metabolic status. These data suggest that during sustained military training, women preferentially mobilize fat stores compared with men, which may be beneficial for mitigating loss of lean mass and lower body power.NEW & NOTEWORTHY Women preferentially mobilize fat stores compared with men in response to sustained, physically demanding military training, as evidenced by increased lipid metabolites and enhanced fat oxidation, which may be beneficial for mitigating loss of lean mass and lower body power.

Cancer researchers' perceptions of the importance of the sex of cell lines, animals, and human samples for cancer biology research.

Sex differences in cancer risk and outcome are currently a topic of major interest in clinical oncology. It is however unknown to what extent cancer researchers consider sex as a biological variable for their research. We conducted an international survey among 1243 academic cancer researchers and collected both quantitative and qualitative data. Although most of the participants indicated that they were familiar with the concept of studying sex differences in cancer biology, they did not think it was important to investigate sex differences in every context of cancer research nor in all tumor types. This is in stark contrast to the current recommendations and guidelines and illustrates the need for increased awareness among cancer researchers regarding the potential impact of the sex of cell lines, animals, and human samples in their studies.

Normative values of hand grip strength in a large unselected Chinese population: Evidence from the China National Health Survey.

Hand grip strength (HGS) is a powerful indicator of sarcopenia and other adverse health outcomes. Normative values for HGS for general Chinese people with a broad age spectrum are lacking. This study aims to establish normative values of HGS and explore the correlations between HGS and body composition among unselected people aged 8-80 in China. From 2012 to 2017, 39655 participants aged 8-80years in the China National Health Survey were included. Absolute HGS was measured using a Jamar dynamometer. The relative HGS was normalized by body mass index. Body composition indexes included body mass index, body fat percentage, muscle mass, fat mass index (FMI) and muscle mass index (MMI). Sex-specific smoothed centile tables for the P1 , P5 , P25 , P50 , P75 , P95 and P99 centiles of HGS and body composition were generated using lambda-mu-sigma method. The correlations between muscle strength and body composition were estimated by partial Spearman correlation analysis. The median values (25th and 75th percentile) of HGS in boys and girls (8-19years old) were 22 (14, 34) kg and 18 (12, 22) kg, respectively; in men and women aged 20-80 were 39 (33, 44) kg and 24 (20, 27) kg, respectively. Values of upper and lower HGS across ages had three periods: an increase to a peak in the 20s in men (with the 5th and 95th values of 30 and 55kg, respectively) and 30s in women (with the 5th and 95th values of 18 and 34kg, respectively), preservation through midlife (20s-40s), and then a decline after their 50s. The lowest HGS values in both sexes were in the 70- to 80-year-old group, with the 5th and 95th percentile values of 16 and 40kg in men, and 10 and 25kg in women. There were substantial sex differences in body composition in the life course (all P values <0.001). In ageing, the decrease of muscle strength was faster than that of muscle mass in both sexes. The correlations between muscle mass and HGS were most robust than other correlations, especially in women (0.68 vs. 0.50), children and adolescents. Our study established the age- and sex-specific percentile reference values for hand grip strength in an unselected Chinese population across a broad age-spectrum. The rich data can facilitate the practical appraisal of muscle strength and promote early prediction of sarcopenia and other impairments associated with neuromuscular disorders.

Sex differences in body composition in people with prediabetes and type 2 diabetes as compared with people with normal glucose metabolism: the Maastricht Study

Aims/hypothesisObesity is a major risk factor for type 2 diabetes. However, body composition differs between women and men. In this study we investigate the association between diabetes status and body composition and whether this association is moderated by sex.MethodsIn a population-based cohort study (n=7639; age 40–75 years, 50% women, 25% type 2 diabetes), we estimated the sex-specific associations, and differences therein, of prediabetes (i.e. impaired fasting glucose and/or impaired glucose tolerance) and type 2 diabetes (reference: normal glucose metabolism [NGM]) with dual-energy x-ray absorptiometry (DEXA)- and MRI-derived measures of body composition and with hip circumference. Sex differences were analysed using adjusted regression models with interaction terms of sex-by-diabetes status.ResultsCompared with their NGM counterparts, both women and men with prediabetes and type 2 diabetes had more fat and lean mass and a greater hip circumference. The differences in subcutaneous adipose tissue, hip circumference and total and peripheral lean mass between type 2 diabetes and NGM were greater in women than men (women minus men [W–M] mean difference [95% CI]: 15.0 cm2 [1.5, 28.5], 3.2 cm [2.2, 4.1], 690 g [8, 1372] and 443 g [142, 744], respectively). The difference in visceral adipose tissue between type 2 diabetes and NGM was greater in men than women (W–M mean difference [95% CI]: −14.8 cm2 [−26.4, −3.1]). There was no sex difference in the percentage of liver fat between type 2 diabetes and NGM. The differences in measures of body composition between prediabetes and NGM were generally in the same direction, but were not significantly different between women and men.Conclusions/interpretationThis study indicates that there are sex differences in body composition associated with type 2 diabetes. The pathophysiological significance of these sex-associated differences requires further study.Graphical abstract

Weight loss induces changes in adaptive thermogenesis in female and male physique athletes.

Physique athletes lose substantial weight preparing for competitions, potentially altering systemic metabolism. We investigated sex differences in body composition, resting energy expenditure (REE), and appetite-regulating and thyroid hormone changes during a competition preparation among drug-free physique athletes. The participants were female (10 competing (COMP) and 10 nondieting controls (CTRL)) and male (13 COMP and 10 CTRL) physique athletes. COMP were tested before they started their diet 23 weeks before competing (PRE), during their diet one week before competing (MID), and 23 weeks after competing (POST), whereas CTRL were tested at similar intervals but did not diet. Measurements included body composition by dual-energy X-ray absorptiometry, muscle size, and subcutaneous fat thickness (SFA) by ultrasound, REE by indirect calorimetry, circulating ghrelin, leptin T3, and T4 hormone analysis. Fat mass (FM) and SFA decreased in both sexes (p<0.001), while males (p<0.001) lost more lean mass (LM) than females (p<0.05). Weight loss, decreased energy intake, and increased aerobic exercise (p<0.05) led to decreased LM- and FM-adjusted REE (p<0.05), reflecting metabolic adaptation. Absolute leptin levels decreased in both sexes (p<0.001) but more among females (p<0.001) due to higher baseline leptin levels. These changes occurred with similar decreases in T3 (p<0.001) and resting heart rate (p<0.01) in both sexes. CTRL, who were former or upcoming physique athletes, showed no systematic changes in any measured variables. In conclusion, while dieting, female and male physique athletes experience REE and hormonal changes leading to adaptive thermogenesis. However, responses seemed temporary as they returned toward baseline after the recovery phase. ClinicalTrials.gov (NCT04392752).

Sex differences in body composition, voluntary wheel running activity, balance performance, and auditory function in CBA/CaJ mice across the lifespan

Hearing loss is the third most prevalent chronic health condition affecting older adults and age-related hearing loss (ARHL) is the most common form of hearing impairment. Significant sex differences in hearing have been documented in humans and rodents. In general, the results of these studies show that men lose their hearing more rapidly than women. However, the cellular mechanism underlying sex differences in hearing or hearing loss remains largely unknown, and to our knowledge, there is no well-established animal model for studying sex differences in hearing. In the current study, we examined sex differences in body composition, voluntary wheel running activity, balance performance, auditory function, and cochlear histology in young, middle-age, and old CBA/CaJ mice, a model of age-related hearing loss. As expected, body weight of young females was lower than that of males. Similarly, lean mass and total water mass of young, middle-age, and old females were lower than those of males. Young females showed higher voluntary wheel running activity during the dark cycle, an indicator of mobility, physical activity, and balance status, compared to males. Young females also displayed higher auditory brainstem response (ABR) wave I amplitudes at 8 kHz, wave II, III, V amplitudes at 8 and 48 kHz, and wave IV/I and V/I amplitude ratios at 48 kHz compared to males. Collectively, our findings suggest that the CBA/CaJ mouse strain is a useful model to study the cellular mechanisms underlying sex differences in physical activity and hearing.

Sex-Specific Changes in Physical Risk Factors for Anterior Cruciate Ligament Injury by Chronological Age and Stages of Growth and Maturation From 8 to 18 Years of Age.

To critically assess the literature focused on sex-specific trajectories in physical characteristics associated with anterior cruciate ligament (ACL) injury risk by age and maturational stage. PubMed, CINAHL, Scopus, and SPORTDiscus databases were searched through December 2021. Longitudinal and cross-sectional studies of healthy 8- to 18-year-olds, stratified by sex and age or maturation on ≥1 measure of body composition, lower extremity strength, ACL size, joint laxity, knee-joint geometry, lower extremity alignment, balance, or lower extremity biomechanics were included. Extracted data included study design, participant characteristics, maturational metrics, and outcome measures. We used random-effects meta-analyses to examine sex differences in trajectory over time. For each variable, standardized differences in means between sexes were calculated. The search yielded 216 primary and 22 secondary articles. Less fat-free mass, leg strength, and power and greater general joint laxity were evident in girls by 8 to 10 years of age and Tanner stage I. Sex differences in body composition, strength, power, general joint laxity, and balance were more evident by 11 to 13 years of age and when transitioning from the prepubertal to pubertal stages. Sex differences in ACL size (smaller in girls), anterior knee laxity and tibiofemoral angle (greater in girls), and higher-risk biomechanics (in girls) were observed at later ages and when transitioning from the pubertal to postpubertal stages. Inconsistent study designs and data reporting limited the number of included studies. Critical gaps remain in our knowledge and highlight the need to improve our understanding of the relative timing and tempo of ACL risk factor development.

ACL Research Retreat IX March 17–19, 2022 High Point, NC

ACL Research Retreat IX March 17–19, 2022 High Point, NC

Substantial but Misunderstood Human Sexual Dimorphism Results Mainly From Sexual Selection on Males and Natural Selection on Females.

Human sexual dimorphism has been widely misunderstood. A large literature has underestimated the effect of differences in body composition and the role of male contest competition for mates. It is often assumed that sexually dimorphic traits reflect a history of sexual selection, but natural selection frequently builds different phenotypes in males and females. The relatively small sex difference in stature (∼7%) and its decrease during human evolution have been widely presumed to indicate decreased male contest competition for mates. However, females likely increased in stature relative to males in order to successfully deliver large-brained neonates through a bipedally-adapted pelvis. Despite the relatively small differences in stature and body mass (∼16%), there are marked sex differences in body composition. Across multiple samples from groups with different nutrition, males typically have 36% more lean body mass, 65% more muscle mass, and 72% more arm muscle than women, yielding parallel sex differences in strength. These sex differences in muscle and strength are comparable to those seen in primates where sexual selection, arising from aggressive male mating competition, has produced high levels of dimorphism. Body fat percentage shows a reverse pattern, with females having ∼1.6 times more than males and depositing that fat in different body regions than males. We argue that these sex differences in adipose arise mainly from natural selection on women to accumulate neurodevelopmental resources.

Sex differences in body composition affect total airway resistance during puberty

BackgroundDuring puberty, changes in body composition due to sex hormones are associated with lung mechanics. However, little is known about the mediation effect of sex differences in body composition during puberty with total airway resistance.MethodsWe prospectively recruited 620 children (10–12 years old) from the general population and conducted a cross-sectional study. This study assessed pubertal status according to the five Tanner stages using a questionnaire, line drawings, and each subject’s blood sex hormone profile. Both the impulse oscillation system for total lung mechanics and multifrequency bioelectrical impedance for body composition analyses were conducted. The effects of puberty on body composition and subsequent total lung resistance were evaluated using mediation analysis.ResultsAmong the 503 children enrolled, there were 261 males (51.9%) and 242 females (48.1%). In males, higher testosterone levels corresponded with reduced total lung resistance (β = –0.13, 95% CI = –0.21 to –0.05, p < 0.001), and the proportion of the mediating effect through the muscle-fat ratio was 19% (95% CI = 4 to 59, p = 0.02). In contrast, in females, pubertal status reduced total lung resistance (β = –0.27, 95% CI = –0.58 to –0.05, p = 0.04), however, the proportion of the mediating effect through the body mass index was –51% (95% CI = –244 to –4%, p = 0.04).ConclusionThe muscle-fat ratio in adolescent males had a synergistic effect with testosterone on improving total airway resistance, whereas improvements in lung resistance by pubertal status were partially masked by body mass index in adolescent females. In conclusion, body composition changes during puberty between males and females have differing effects on total airway resistance.

Sex Differences in the Association Between Muscular Strength and Adiposity in Healthy Adults

ABSTRACT Although sex differences in body composition are well established, differences in the relationship between adiposity and muscular strength remain elusive. Thus, the aim of this study was to determine sex differences in the relationship between muscular strength and adiposity in adults. Body mass index (BMI), waist circumference (WC), waist-to-height ratio (WtHR), skinfold, and bench press were assessed on 140 males and females aged 18-40 years. Normalized strength (NS) was determined by dividing bench press one-repetition maximum by body mass. Using linear regression, positive associations between NS and BMI were found in males [p=0.003, parameter estimate (PE)=0.051] and females (p=0.010, PE=0.021); inverse associations between NS and body fat percentage were found in males (p&lt;0.001, PE=-0.035) and females (p=0.015, PE=-0.008); an inverse association between NS and WC was observed only amongst females (p=0.037, PE=-0.011); and no significant associations were found between NS and (WtHR) for either sex. Although the current study design does not permit determining causality, the findings suggest that resistance training may be more effective in reducing abdominal adiposity in females.

Association of Predicted Lean Body Mass and Fat Mass With Incident Diabetic Nephropathy in Participants With Type 2 Diabetes Mellitus: A Post Hoc Analysis of ACCORD Trial.

BackgroundLean body mass (LBM) and fat mass (FM) have been shown to have different associations with several chronic diseases but little is known about the sex-specific association of LBM and FM with diabetic nephropathy (DN) risk among participants with diabetes.MethodsParticipants from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study was used in a post hoc analysis to examine the association of predicted LBM index (LBMI) and FM index (FMI) with incident DN risk (defined as a composite outcome of three types of predefined DN). Because of sex differences in body composition, analyses were conducted separately using sex-specific quartiles of predicted LBMI and FMI.ResultsOf the 9,022 participants with type 2 diabetes (5,575 men and 3,447 women) included in this study, 5,374 individuals developed DN (3,396 in men and 1,978 in women). Higher quartiles of LBMI were associated with a reduced risk of DN while higher quartiles of FMI were associated with an increased higher risk of DN among men but not women. Compared with the lowest quartile, the fully adjusted hazard ratios (HRs) and 95% confidence intervals (CIs)for the highest quartile of predicted LBMI and FMI were respectively 0.83 (95% CI 1.71 – 0.96) and 1.23 (95% CI 1.06-1.43) among men; and 0.92 (95% CI 0.63 – 1.33) and 1.14 (95% CI 0.79 – 1.63) among women.ConclusionsAmong participants with diabetes, predicted LBMI was inversely associated with risk of DN while predicted FMI was positively associated with an increased risk of incident DN among men but not women. Trial registration: ClinicalTrials.gov., no. NCT00000620.

Sex Differences in Body Composition and Fitness Scores in Military Reserve Officers' Training Corps Cadets.

The cadets in the U.S. Army Reserve Officers' Training Corps (ROTC) consist of students from varied backgrounds. As part of collegiate ROTC programs, cadets must pass fitness tests and adhere to body composition standards in addition to completing their education. The previous fitness test of record was the Army Physical Fitness Test (APFT), but it was recently changed to the Army Combat Fitness Test (ACFT) to better test soldiers for combat capabilities. As part of the standardized scoring, the ACFT is no longer separated by sex or age as in the APFT, but rather by job duty. The purpose of this study was to characterize the modern ROTC cadet based on body composition measures and APFT and ACFT scores and then determine how those factors are related. We calculated body mass index (BMI), fat mass, fat-free mass (FFM), fat-free mass index (FFMI), and fat mass index (FMI) (n = 68, 42 males, 26 females). We used Pearson correlations to compare the scores to body composition assessments and Student's t-tests to determine if there were differences between sexes. We hypothesized that those with higher FFM and FFMI will have a higher passing rate on the ACFT and that males would perform better on the ACFT because of having more FFM. We found that cadets, regardless of sex, were borderline overweight using BMI standards and that BMI did not correlate with any fitness tests. When comparing sexes, both males and females had high passing rates on the APFT, but females struggled to pass the ACFT mostly because of the leg tuck. We also found that ACFT scores were strongly correlated with FFM and FFMI, yet no body composition measures were correlated with APFT scores. It is clear from our data that structured training programs and nutrition guidance are needed with an emphasis on changing body composition to increase lean mass and strength to increase the performance of ROTC cadets on the ACFT.

Beyond Body Mass Index - Body Composition Assessment by Bioimpedance in Routine Endocrine Practice

ObjectiveTo explore the body composition of pediatric patients referred for endocrine evaluation. MethodsThis real-life observational study conducted between January 2018 and January 2020 included 10 001 clinic visits of 3500 children and adolescents; first visits of 5 to 18-year-old patients were included. Anthropometric data, blood pressure levels, pubertal status, and bioelectrical impedance analysis (BIA, Tanita MC-780 MA) were extracted from medical files. Excluded from the analysis were patients participating in other studies. ResultsA total of 1001 patients (48% boys, mean age 11.3 ± 3.4 years, 33.5% prepubertal) were included. Mean anthropometric z-scores were normal and similar for boys and girls. Sex differences in body composition were as follows: boys had lower fat percentage, lower truncal fat percentage, higher appendicular skeletal muscle mass, and a higher muscle-to-fat ratio (MFR) than girls (P < .001 for all). MFR correlated with body mass index-standard deviation scores (BMI-SDS) in overweight/obese patients (r = −0.558, P < .001), although not in underweight patients. Systolic blood pressure (SBP) correlated with BMI-SDS in overweight/obese patients (r = 0.262, P < .001), although not in underweight patients. Diastolic blood pressure (DBP) did not correlate with BMI-SDS in either group of extreme weight status. MFR correlated with SBP and DBP in overweight/obese patients (r = −0.230, P < .001 and r = −0.141, P = .018, respectively) as well as in underweight patients (r = 0.331, P < .001 and r = 0.264, P = .005, respectively). ConclusionsOur findings support BIA for a more refined characterization of patients referred for endocrine evaluation than BMI-SDS. MFR may be a better surrogate marker of blood pressure levels than BMI-SDS in both underweight and overweight/obese pediatric patients.

Sex differences in body composition in non‐demented individuals with autosomal dominant Alzheimer’s disease

AbstractBackgroundBody mass index (BMI) is a known risk factor for Alzheimer’s disease (AD). Research with autosomal dominant Alzheimer’s disease (ADAD) has shown a relationship between lower BMI, greater amyloid burden and worse memory performance in presymptomatic mutation carriers. Women have a higher incidence of AD, and may be more susceptible to AD‐ related pathology. However, little is known about the effects of sex/gender on BMI in individuals at increased risk for AD. As carriers of ADAD mutations are destined to develop early‐onset dementia, they allow us to investigate sex differences without aging confounds known to vary by sex (i.e., life expectancy, menopause). We sought to examine sex differences in BMI in non‐demented mutation carriers and non‐carriers from a Colombian kindred with ADAD.Method191 carriers of the Presenilin‐1 E280A mutation (104 females; age range: 18‐55 years) and 261 age‐matched non‐carriers (165 females) were included. All participants completed clinical and cognitive assessments, including BMI (kg/m2) measures, MMSE and CERAD Word List tests. Mann‐Whitney‐U test was used to examine sex differences on BMI. General linear models were used to examine the associations between BMI, MMSE and memory, controlling for age and education.ResultCompared to non‐carriers, carriers had lower BMI (carriers: 23.05 +/‐ 3.65; non‐carriers: 24.26 +/‐ 3.92, p=0.002). In carriers, lower BMI was associated with worse performance on MMSE (r=0.49, p=0.001). Compared to male carriers, female carriers had greater BMI (males: 22.4 +/‐ 3.3, females: 23.5 +/‐ 3.7, p=0.04), and performed worse on the MMSE (males: 28.19 +/‐1.8, females: 27.91 +/‐1.91, p=0.04). There was a trend for female carriers to also have worse memory performance (p=0.06). Sex differences were not observed in non‐carriers. There were no associations between BMI and memory.ConclusionThere are sex differences in body composition in carriers of ADAD without dementia. These findings suggest that changes in BMI may reflect early signs of abnormal systemic responses to AD‐related pathology. Future studies should examine longitudinal changes in BMI, from preclinical to clinical stages, and other contributing factors (e.g. vascular risk factors and sex hormones) to determine the potential role of BMI as a risk factor for dementia.