Longitudinal associations of the endocrine environment on fat partitioning in postmenopausal women

Aging versus youth: Endocrine aspects of vulnerability for COVID-19

Coronavirus Disease 2019 (COVID-19) is characterized with a wide range of clinical presentations from asymptomatic to severe disease. In patients with severe disease, the main causes of mortality have been acute respiratory distress syndrome, cytokine storm and thrombotic events. Although all factors that may be associated with disease severity are not yet clear, older age remains a leading risk factor. While age-related immune changes may be at the bottom of severe course of COVID-19, age-related hormonal changes have considerable importance due to their interactions with these immune alterations, and also with endothelial dysfunction and comorbid cardiometabolic disorders. This review aims to provide the current scientific evidence on the pathogenetic mechanisms underlying the pathway to severe COVID-19, from a collaborative perspective of age-related immune and hormonal changes together, in accordance with the clinical knowledge acquired thus far.

FSH Level and Changes in Bone Mass and Body Composition in Older Women and Men

CONTEXT

FSH may have independent actions on bone remodeling and body fat regulation. Cross-sectionally, we have shown that serum FSH is associated with bone mineral density (BMD) and body fat in older postmenopausal women, but it remains unknown whether FSH predicts bone and fat changes.

OBJECTIVE

We examined whether baseline FSH level is associated with subsequent bone loss or body composition changes in older adults.

SETTING, DESIGN, PARTICIPANTS

We studied 162 women and 158 men (mean age 82 ± 4 years) from the Age, Gene/Environment Susceptibility (AGES)-Bone Marrow Adiposity cohort, a substudy of the AGES-Reykjavik Study of community-dwelling older adults. Skeletal health and body composition were characterized at baseline and 3 years later.

MAIN OUTCOMES

Annualized change in BMD and body composition by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT). Models were adjusted for serum estradiol and testosterone levels.

RESULTS

There was no evidence for an association between baseline FSH level and change in BMD or body composition by DXA or QCT. For femoral neck areal BMD, adjusted mean difference (95% CI) per SD increase in FSH was 1.3 (-0.7 to 3.3) mg/cm2/y in women, and -0.2 (-2.6 to 2.2) mg/cm2/y in men. For visceral fat, adjusted mean difference (95% CI) per SD increase in FSH was 1.80 (-0.03 to 3.62) cm2/y in women, and -0.33 (-3.73 to 3.06) cm2/y in men.

CONCLUSIONS

Although cross-sectional studies and studies in perimenopausal women have demonstrated associations between FSH and BMD and body composition, in older adults, FSH level is not associated with bone mass or body composition changes.

Body Composition Methods in Adults with Type 2 Diabetes or at Risk for T2D: a Clinical Review

PURPOSE OF REVIEW

The aim of this study is to summarize anthropometric and advanced methods used to assess body composition in adults diagnosed with type 2 diabetes (T2D) or at risk for T2D that provide clinically relevant information about T2D disease-related complications or risk factors.

RECENT FINDINGS

Anthropometry is commonly used in clinical settings; however, provides unreliable estimates of fat mass, fat-free mass, and body fat distribution for metabolic health assessments compared to advanced techniques such as bioelectrical impedance analysis (BIA), dual-energy x-ray absorptiometry (DXA), computerized tomography (CT), and magnetic resonance imaging (MRI). Few studies report the clinical use of anthropometric and advanced body composition methods that identify T2D disease-related complications or T2D risk factors. Anthropometry, BIA, DXA, CT, and MRI were used to estimate body adiposity and distribution, visceral and subcutaneous adipose tissue depots, and skeletal muscle mass. Review findings indicate that these methods were capable of identifying clinically relevant T2D disease-related complications such as sarcopenia and T2D risk factors such as obesity or regional adiposity. However, estimates were often sex and race/ethnicity specific warranting cross-validation of these methods in broader populations with T2D or risk for T2D prior to clinical implementation.

Increased body fat mass explains the positive association between circulating estradiol and insulin resistance in postmenopausal women

The relationship between circulating estrogen levels and cardiometabolic risk factors such as insulin resistance is unclear in postmenopausal women. High estradiol (E₂) levels have been reported to predict increased risk of type 2 diabetes in this population. We aimed to examine associations among estrogen levels, adiposity measurements, and cardiometabolic risk variables including insulin resistance in postmenopausal women. One hundred-one healthy participants (mean ± SD: age 57 ± 4 yr, BMI 27.9 ± 4.8 kg/m²) were included in the analysis. Fifteen plasma steroids or metabolites were measured by liquid chromatography-tandem mass spectrometry. Insulin sensitivity was assessed with a hyperinsulinemic-euglycemic clamp. Body composition and fat distribution were determined with hydrostatic weighing and computed tomography, respectively. Blood lipids and circulating cytokines were also measured. Circulating E₂ was positively correlated with all adiposity indexes ( r = 0.62 to 0.42, P < 0.0001) except waist-to-hip ratio. E₂ was positively correlated with VLDL-cholesterol, plasma-, VLDL-, and HDL-triglyceride levels ( r = 0.31 to 0.24, P < 0.02) as well as with hs-CRP and IL-6 ( r = 0.52 and 0.29, P < 0.005) and negatively with HDL-cholesterol, adiponectin, and insulin sensitivity ( r = -0.36 to -0.20, P < 0.02). With adjustments for percent body fat, correlations between E₂ and metabolic risk variables were no longer significant. Similar results were observed for circulating estrone (E₁) and estrone-sulfate (E₁-S) levels. In conclusion, circulating estrogen concentrations are proportional to adipose mass in postmenopausal women, although they remain in the low range. Insulin resistance as well as altered blood lipids and cytokines are observed when circulating estrogen levels are high within that range, but these differences are explained by concomitant variation in total adiposity.

Causes and mechanisms of adipocyte enlargement and adipose expansion

Adipose tissue plays a significant role in whole body energy homeostasis. Obesity-associated diabetes, fatty liver and metabolic syndrome are closely linked to adipose stress and dysfunction. Genetic predisposition, overeating and physical inactivity influence the expansion of adipose tissues. Under conditions of constant energy surplus, adipocytes become hypertrophic and adipose tissues undergo hyperplasia so as to increase their lipid storage capacity, thereby keeping circulating blood glucose and fatty acids below toxic levels. Nonetheless, adipocytes have a saturation point where they lose capacity to store more lipids. At this stage, when adipocytes are fully lipid-engorged, they express stress signals. Adipose depots (particularly visceral compartments) from obese individuals with a severe metabolic phenotype are characterized by the high proportion of hypertrophic adipocytes. This review focuses on the mechanisms of adipocyte enlargement in relation to adipose fatty acid and cholesterol metabolism, and considers how this may be related to adipose dysfunction.

Response of Gait Output and Handgrip Strength to Changes in Body Fat Mass in Pre- and Postmenopausal Women

BACKGROUND

Available preliminary data on menopause does not relate changes in body fat mass (BFM) and handgrip strength (HGS) (an indicator of body/muscle strength) to gait parameters.

OBJECTIVE

To determine the relationship between BFM, HGS and gait parameters, namely, stride length (SL) (an indicator of walking balance/postural stability), stride frequency (SF), and velocity (V) (gait output), to guide gait training.

METHODS

Ninety consenting (45 postmenopausal and 45 premenopausal) female staff of the University of Nigeria Teaching Hospital, Enugu, were randomly selected and assessed for BFM and HGS with a hydration monitor and dynamometer, respectively, in an observational study. The mean of 2 trials of the number of steps and time taken to cover a 10-m distance at normal speed was used to calculate SF, SL, and V. Data were analyzed using an independent t test and a Pearson correlation coefficient at P < 0.05.

RESULTS

Premenopausal (BFM = 42.93% [12.61%], HGS = 27.89 [7.52] kg, stride ratio = 1.43, and velocity = 1.04 [0.01] m/sec) and postmenopausal (BFM = 41.55% [12.71%], HGS = 30.91 [7.07] kg, stride ratio = 1.44, and velocity = 1.06 [0.01] m/sec) women showed no significant differences in gait output/velocity (t = 0.138; P = 0.89; d = 0.029). At postmenopause, BFM was significantly and negatively (r = -0.369; r 2 = 0.1362; P = 0.013) correlated with SL, whereas HGS was positively and significantly (r = 0.323; r 2 = 0.104; P = 0.030) correlated with gait output at premenopause.

CONCLUSIONS

BFM may adversely influence walking balance at postmenopause, whereas HGS may enhance gait output at premenopause but not postmenopause. Therefore, muscle strengthening alone may not enhance gait output in postmenopausal women without balance training.

Association of Mid-Life Changes in Body Size, Body Composition and Obesity Status with the Menopausal Transition

The mid-life period is a critical window for increases in body weight and changes in body composition. In this review, we summarize the clinical experience of the menopausal transition by obesity status, and examine the evidence regarding the menopausal transition and reproductive hormones effects on body weight, body composition, or fat distribution. Mid-life obesity is associated with a different menopausal experience including associations with menstrual cycle length prior to the final menstrual period (FMP), age at the FMP, and higher prevalence of vasomotor symptoms. The menopausal transition is associated with weight gain and increased central body fat distribution; the majority of evidence suggests that changes in weight are due to chronological aging whereas changes in body composition and fat distribution are primarily due to ovarian aging. Continuous and regular physical activity during mid-life may be an efficacious strategy to counteract the age-related and menopause-related changes in resting energy expenditure and to prevent weight gain and abdominal adiposity deposition.

Covariation of change in bioavailable testosterone and adiposity in midlife women

OBJECTIVE

To determine whether menopause-related changes in reproductive hormones were associated with change in adiposity and whether these relationships were independent of important covariates.

METHODS

Annual assessments of adiposity measures [computed tomography-assessed visceral adipose tissue (VAT) and subcutaneous abdominal adipose tissue (SAT) and dual-energy X-ray absorptiometry-assessed total body fat (TBF)] over 4 years from an ancillary study at the Chicago site of the Study of Women's Health Across the Nation (SWAN) were paired with reproductive hormones collected by SWAN. Included were 243 women (44% African American, 56% Caucasian) who were eligible participants in a population-based cohort with a 72% participation rate.

RESULTS

VAT increased by 3.8% annually, and SAT increased by 1.8% per year. Change in bioavailable testosterone was significantly positively associated with changes both in VAT and in SAT but was not related to change in total body fat. The associations were independent of age, race, physical activity, smoking, baseline TBF, baseline bioavailable testosterone, and change in TBF. Change in estradiol was unrelated to changes in any adiposity measure.

CONCLUSIONS

Bioavailable testosterone may play an important role in menopause-related redistribution of visceral and subcutaneous fat in the central abdominal region.

The genetics of fat distribution

Fat stored in visceral depots makes obese individuals more prone to complications than subcutaneous fat. There is good evidence that body fat distribution (FD) is controlled by genetic factors. WHR, a surrogate measure of FD, shows significant heritability of up to ∼60%, even after adjusting for BMI. Genetic variants have been linked to various forms of altered FD such as lipodystrophies; however, the polygenic background of visceral obesity has only been sparsely investigated in the past. Recent genome-wide association studies (GWAS) for measures of FD revealed numerous loci harbouring genes potentially regulating FD. In addition, genes with fat depot-specific expression patterns (in particular subcutaneous vs visceral adipose tissue) provide plausible candidate genes involved in the regulation of FD. Many of these genes are differentially expressed in various fat compartments and correlate with obesity-related traits, thus further supporting their role as potential mediators of metabolic alterations associated with a distinct FD. Finally, developmental genes may at a very early stage determine specific FD in later life. Indeed, genes such as TBX15 not only manifest differential expression in various fat depots, but also correlate with obesity and related traits. Moreover, recent GWAS identified several polymorphisms in developmental genes (including TBX15, HOXC13, RSPO3 and CPEB4) strongly associated with FD. More accurate methods, including cardiometabolic imaging, for assessment of FD are needed to promote our understanding in this field, where the main focus is now to unravel the yet unknown biological function of these novel 'fat distribution genes'.