Body fat has stronger associations with bone mass density than body mass index in metabolically healthy obesity

Metabolically healthy obesity and health risks - a review of meta-analyses

OBJECTIVE

This article briefly summarizes the results of existing research on metabolically healthy obesity in the context of health risks.

METHODS

The PubMed database was searched for relevant meta-analyses addressing metabolically healthy obesity in the context of health risks.

RESULTS

We included a total of 17 relevant meta-analyses in this review. The results of the studied meta-analyses showed that metabolically healthy obesity may be only a transient condition associated with an increased risk of developing metabolic abnormalities in the future. People with obesity without metabolic abnormalities have an increased risk of type 2 diabetes, cardiovascular disease, cancer, chronic kidney disease, and depressive syndrome. In addition, all people with obesity are at risk of pathogenesis resulting from the mechanical stress caused by presence of abnormal adipose tissue, such as sleep apnoea syndrome or skin problems.

CONCLUSION

Based on the results of meta-analyses, we recommend motivating all obese patients to change their lifestyle regardless of the presence of metabolic defects.

Association between normal-weight obesity and bone mineral density in older Korean adults: A population-based cross-sectional study

The effects of normal-weight obesity, which is defined as having a high level of body fat despite a normal body mass index, on the health of bones in older adults are poorly understood. This cross-sectional study examined the relationship between normal-weight obesity and bone mineral density in Korean adults aged 50 years or more (2815 men and 2744 women) from the 2008-2011 Korea National Health and Nutrition Examination Surveys. Between the ages of 50 and 69 years, individuals with normal-weight obesity had a higher risk of low bone mineral density (odds ratio = 1.596, 95 % confidence interval = 1.189-2.141, p = 0.002) compared with individuals with normal-weight non-obesity. However, no significant association between normal-weight obesity and bone mineral density was observed among people between the ages of 70 and 89 years. The study findings support the clinical significance of normal-weight obesity as a proxy biomarker to identify in primary care settings people who are at increased risk of developing osteoporosis at an early stage of aging.

Sexual dimorphism of osteoclast reliance on mitochondrial oxidation of energy substrates in the mouse

Osteoclasts specialize in bone resorption and are critical for bone remodeling. Previous studies have shown that osteoclasts possess abundant mitochondria and derive most energy through oxidative phosphorylation (OXPHOS). However, the energy substrates fueling OXPHOS in osteoclasts remain to be fully defined. Here, we showed that osteoclast differentiation was coupled with increased oxidation of glucose, glutamine, and oleate. Transcriptomic analyses with RNA sequencing revealed marked upregulation of genes participating in OXPHOS and mitochondrial fatty acid oxidation, during osteoclast differentiation. Increased mitochondrial oxidation of long-chain fatty acids was required for osteoclast differentiation in vitro. However, blocking fatty acid oxidation in vivo, by deletion of carnitine palmitoyltransferase 1a (Cpt1a) in osteoclast progenitors, impaired osteoclast formation only in the female mice. The Cpt1a-deficient females were further protected from osteoclast activation by a high-fat diet. The males, on the contrary, exhibited normal bone resorption despite Cpt1a deletion, regardless of the dietary fat content. Moreover, concurrent deletion of mitochondrial pyruvate carrier 1 and Cpt1a, blocking mitochondrial oxidation of both glucose and fatty acids in the osteoclast lineage, failed to impede bone resorption in the males. The study therefore uncovers a female-specific dependence on mitochondrial oxidation of fatty acids and glucose in osteoclasts in vivo.

A Prediction Model for Osteoporosis Risk Using a Machine-Learning Approach and Its Validation in a Large Cohort

BACKGROUND

Osteoporosis develops in the elderly due to decreased bone mineral density (BMD), potentially increasing bone fracture risk. However, the BMD is not regularly measured in a clinical setting. This study aimed to develop a good prediction model for the osteoporosis risk using a machine learning (ML) approach in adults over 40 years in the Ansan/Anseong cohort and the association of predicted osteoporosis risk with a fracture in the Health Examinees (HEXA) cohort.

METHODS

The 109 demographic, anthropometric, biochemical, genetic, nutrient, and lifestyle variables of 8,842 participants were manually selected in an Ansan/Anseong cohort and included in the ML algorithm. The polygenic risk score (PRS) of osteoporosis was generated with a genome-wide association study and added for the genetic impact of osteoporosis. Osteoporosis was defined with < -2.5 T scores of the tibia or radius compared to people in their 20s-30s. They were divided randomly into the training (n = 7,074) and test (n = 1,768) sets-Pearson's correlation between the predicted osteoporosis risk and fracture in the HEXA cohort.

RESULTS

XGBoost, deep neural network, and random forest generated the prediction model with a high area under the curve (AUC, 0.86) of the receiver operating characteristic (ROC) with 10, 15, and 20 features; the prediction model by XGBoost had the highest AUC of ROC, high accuracy and k-fold values (> 0.85) in 15 features among seven ML approaches. The model included the genetic factor, genders, number of children and breastfed children, age, residence area, education, seasons to measure, height, smoking status, hormone replacement therapy, serum albumin, hip circumferences, vitamin B6 intake, and body weight. The prediction models for women alone were similar to those for both genders, with lower accuracy. When the prediction model was applied to the HEXA study, the correlation between the fracture incidence and predicted osteoporosis risk was significant but weak (r = 0.173, P < 0.001).

CONCLUSION

The prediction model for osteoporosis risk generated by XGBoost can be applied to estimate osteoporosis risk. The biomarkers can be considered for enhancing the prevention, detection, and early therapy of osteoporosis risk in Asians.

Evaluation of Liver Metabolism Biomarkers in Metabolic Associated Fatty Liver Disease According to Obesity Phenotype

OBJECTIVE

To analyze the relationship between the biochemical markers of liver metabolism in different stages of Metabolic Associated Fatty Liver Disease (MAFLD) according to the obesity phenotype.

METHODOLOGY

This is a cross-sectional study with individuals with class III obesity classified according to the obesity phenotypes proposed by the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. Biochemical and anthropometric variables were analyzed according to the staging of MAFLD and obesity phenotype.

RESULTS

A total of 50 subjects with MAFLD, 62% (n = 31) with steatosis and 38% (n = 19) with steatohepatitis without fibrosis; 36% were classified as metabolically healthy obesity (MHO) and 64% as metabolically unhealthy obesity (MUHO), respectively. Mean values of alkaline phosphatase were 85.44 ± 27.27 vs. 61.92 ± 17.57 (p = 0.006); gamma-glutamyl transpeptidase, 25.77 ± 15.36 vs. 30.63 ± 19.49 (p = 0.025); and albumin, 3.99 ± 0.34 vs. 4.24 ± 0.23 (p = 0.037), were lower and statistically significant in the MHO group with steatosis. The results show when considering individuals with IR, only AP is a predictor of unhealthy phenotype (B-0.934, 0.848- 1.029, p = 0.031).

CONCLUSION

MHO individuals with steatosis present lower severe changes related to markers of liver damage and function and AP is considered the predictor of MUHO phenotype.

Body Fat Percentage and the Long-term Risk of Fractures. The EPIC-Norfolk Prospective Population Cohort Study

BACKGROUND

This cohort study aimed to determine the association between body fat percentage (BF%), incident fractures and calcaneal broadband ultrasound attenuation (BUA).

METHODS

Participants were drawn from the EPIC-Norfolk Prospective Population Cohort Study (median follow-up = 16.4 years). Cox models analysed the relationship between BF% and incident fractures (all and hip). Linear and restricted cubic spline (RCS) regressions modelled the relationship between BF% and BUA.

RESULTS

14,129 participants (56.2 % women) were included. There were 1283 and 537 incident all and hip fractures respectively. The participants had a mean (standard deviation) age of 61.5 (9.0) years for women and 62.9 (9.0) years for men. Amongst men, BF% was not associated with incident all fractures. While BF% < 23 % (median) was not associated with hip fractures, BF% > 23 % was associated with increased risk of hip fractures by up to 50 % (hazard ratio (95 % confidence interval) = 1.49 (1.06-2.12)). In women, BF% < 39 % (median) was associated with up to 32 % higher risk of all fractures (1.32 (1.13-1.44)), while BF% > 35 % was not associated with this outcome. Higher BF% was associated with lower risk of incident hip fractures in women. Higher BF% was associated with higher BUA amongst women. Higher BF% up to ~23 % was associated with higher BUA amongst men.

CONCLUSIONS

Higher BF% is associated with lower risk of fractures in women. While there was no association between BF% and all fractures in men, increasing BF% >23 % was associated with higher risk of hip fractures in men. This appears to be independent of estimated bone mineral density. Fracture prevention efforts need to consider wider physical, clinical, and environmental factors.

Nonalcoholic fatty liver disease and osteoporosis: A potential association with therapeutic implications

Nonalcoholic fatty liver disease (NAFLD) and osteoporosis are two highly prevalent metabolic diseases. Increasing experimental evidence supports a pathophysiological link between NAFLD and osteoporosis. A key feature could be chronic, low-grade inflammation, which characterizes NAFLD and possibly affects bone metabolism. In this context, several factors, including but not limited to receptor activator of nuclear factor kappa-B ligand, osteoprotegerin, osteopontin and osteocalcin, may serve as mediators. In the clinical setting, most but not all epidemiological evidence indicates that NAFLD is associated with lower bone mineral density or osteoporosis in adults. Although an association between NAFLD and osteoporosis has not yet been established, and thus remains speculative, pharmacological considerations already exist. Some of the current and emerging pharmacological options for NAFLD have shown possible anti-osteoporotic properties (eg, vitamin E, obeticholic acid, semaglutide), while others (eg, pioglitazone, canagliflozin) have been associated with increased risk of fractures and may be avoided in patients with NAFLD and concomitant osteoporosis, especially those at high fracture risk. Conversely, some anti-osteoporotic medications (denosumab) might benefit NAFLD, while others (raloxifene) might adversely affect it and, consequently, may be avoided in patients with osteoporosis and NAFLD. If an association between NAFLD and osteoporosis is established, a medication that could target both diseases would be a great advancement. This review summarizes the main experimental and clinical evidence on the potential association between NAFLD and osteoporosis and focuses on treatment considerations derived from this potential association.

The Relationship Between Bone Mineral Density and Body Composition Among Qatari Women With High Rate of Obesity: Qatar Biobank Data

Studies have reported inconsistent results for the relationship between body composition and bone mineral density (BMD) among women, especially those with a high rate of obesity. This study aims to examine the association between BMD and body composition among Qatari women. A cross-sectional study, using data from the Qatar Biobank (QBB), was conducted on 2,000 Qatari women aged 18 and over. Measurements were taken by dual-energy X-ray absorptiometry (DEXA) for body composition [visceral fat and android fat (AF)], gynoid fat (GF), trunk fat, total fat mass (TFM), total lean mass (LM) and bone mineral density (BMD), including the lumber spine, neck, femur and total body. The participants were divided into groups of normal and low BMD, based on their T-score. Non-linear regression analysis using the restricted cubic spline method was performed according to the T-score of the total BMD for the fat mass variables. Women with a low BMD (T-score <-1) had significantly lower body composition indicators. LM was positively correlated with BMD at the spine (r = 0.29, p < 0.001), neck (r = 0.32, p < 0.001), and femur (r = 0.28, p < 0.001), as well as total BMD (r = 0.29, p < 0.001) and T-score (r = 0.31, p < 0.001), while the correlatio between TFM and BMD was negative and weak (r = -0.05, <0.017). Results of the non-linear regression indicated that components of fat distribution (TFM, AF, GF and trunk fat) were positively associated with total body T-score. In the adjusted non-liner regression, only a slight increase in T-score was recorded with an increase in FM. The association between FM and BMD was non-linear, suggesting that FM may not be a strong protector of bones among women with high rate of obesity.

Regular Exercise and Weight-Control Behavior Are Protective Factors against Osteoporosis for General Population: A Propensity Score-Matched Analysis from Taiwan Biobank Participants

The rising prevalence of osteoporosis, which can lead to osteoporotic fractures, increases morbidity, mortality, and socioeconomic burden. Multiple factors influencing bone mass have already been identified. The aim of this study was to investigate whether exercise habits and weight-control behaviors can lower the incidence of osteoporosis in the general population. This retrospective study recruited all participants aged 35–70 years who underwent dual-energy X-ray absorptiometry (DXA) from Taiwan Biobank (TWB). The final analysis consisted of 3320 eligible participants divided into two groups; demographic characteristics, prevalence of clinical symptoms, comorbidities, and daily behavior were collected using a self-reported questionnaire. After propensity score matching with a 1:1 ratio, 1107 out of 2214 individuals were classified into the osteoporosis group. Age, body fat rate, body shape, diabetes mellitus, and social status were found to affect the incidence of osteoporosis. Subjects with a habit of regular exercise and weight-control behavior showed decreased odds of osteoporosis. (odds ratio: 0.709 and 0.753, 95% confidence interval: 0.599–0.839 and 0.636–0.890). In the general population, regular exercise or weight-control behavior lowers the incidence of osteoporosis.

Linear and non-linear associations between physical activity, body composition and multimorbidity over 10 years among community-dwelling older adults

BACKGROUND

This study aims to describe the relationships between physical activity (PA), body composition and multimorbidity over 10 years.

METHODS

Participants (N=373; 49% women; average age 61.3±6.7 years) were followed for 10 years. Multimorbidity was defined by self-report as the presence of two or more of 12 listed chronic conditions. PA (steps-per-day) at baseline was assessed by pedometer, handgrip strength (HGS) by dynamometer and appendicular lean mass (ALM) and total body fat mass by dual x-ray absorptiometry . Relative HGS and ALM were calculated by dividing each body mass index (BMI). Regression cubic splines were used to assess evidence for a non-linear relationship.

RESULTS

After 10 years, 45% participants had multimorbidity. There was a non-linear relationship between PA and multimorbidity - PA was associated with lower multimorbidity risk among individuals who engaged in <10,000 steps-per-day (RR=0.91, 95% CI: 0.85, 0.97, per 1000 steps-per-day), but not among those who participated in ≥10,000 steps-per-day (RR=1.04, 95% CI: 0.93, 1.09, per 1000 steps-per-day). Higher BMI (RR=1.05, 95% CI: 1.02, 1.08, per kg/m 2) and fat mass (RR=1.03, 95% CI: 1.01, 1.04, per kg), and lower relative HGS (RR=0.85, 95% CI: 0.77, 0.94, per 0.1 psi/kg/m 2) and ALM (RR=0.93, 95% CI: 0.88, 0.98, per 0.1 kg/kg/m 2) were linearly associated with a higher risk of multimorbidity. Absolute HGS and ALM were not significantly associated with multimorbidity.

DISCUSSION

These findings highlight the potential clinical importance of maintaining adequate levels of PA and of reducing adiposity and maintaining muscle function for minimising the risk of multimorbidity in older adults.

Incidence and predictors of fractures in older adults with and without obesity defined by body mass index versus body fat percentage

PURPOSE

The aim of this study was to determine and compare risk factors associated with incident fractures in older adults with and without obesity, defined by both body mass index (BMI) and body fat percentage.

METHODS

1,099 older adults (mean ± standard deviation age = 63.0 ± 7.5) years, participated in this prospective cohort study. Obesity status at baseline was defined by BMI (≥30 kg/m²) obtained by anthropometry and body fat percentage (≥30% for men and ≥40% for women) assessed by dual-energy X-ray absorptiometry (DXA). Total hip and lumbar spine areal bone mineral density (aBMD) were assessed by DXA up to five years. Incident fractures were self-reported up to 10 years.

RESULTS

Prevalence of obesity was 28% according to BMI and 43% according to body fat percentage. Obese older adults by BMI, but not body fat percentage, had significantly higher aBMD at the total hip and spine compared with non-obese (both p-value<0.05). Obese older adults by body fat percentage had significantly higher likelihood of all incident fractures (OR: 1.71; CI:1.08, 2.71) and non-vertebral fractures (OR: 1.88; CI:1.16, 3.04) compared with non-obese after adjusting for confounders. Conversely, obese older adults by BMI had a significantly lower likelihood (OR: 0.54; CI:0.31, 0.94) of non-vertebral fractures although this was no longer significant after adjustment for total hip aBMD (all p-value > 0.05). Mediation analysis confirmed that aBMD meditated the effects of BMI, but not body fat percentage, on all incident fractures. Higher baseline falls risk score was the only consistent predictor of increased likelihood of incident fracture in obese individuals only, according to both BMI and body fat percentage (both p-value<0.05).

CONCLUSIONS

Obesity defined by body fat percentage is associated with increased likelihood of incident fractures in community-dwelling older adults, whereas those who are obese according to BMI have reduced likelihood of incident fracture which appears to be explained by higher aBMD. Falls risk assessment may improve identification of obese older adults at increased risk of incident fractures.

Bone density, microarchitecture and strength estimates in white versus African American youth with obesity

BACKGROUND

African Americans (AA) have more favorable bone density and microarchitecture compared to Whites (W), which may explain their observed lower fracture rates. Obesity has deleterious effects on bone microarchitecture and strength estimates and is associated with an increase in fracture risk. Adolescence and young adulthood are periods of active bone accrual and also periods characterized by an increasing prevalence of obesity. The effect of obesity on the relationship between race and bone parameters remains unclear, particularly in youth.

OBJECTIVE

To assess differences in BMD, bone microarchitecture and strength estimates in AA and W adolescents and young adults with moderate to severe obesity. We hypothesized that racial differences in bone endpoints in lean youth would also be noted in youth with moderate to severe obesity.

METHODS

We evaluated 24 AA and 48 W adolescent and young adults with a mean age of 18.2 ± 2.4 years and a median body mass index (BMI) of 44.8 (40.5-49.4) kg/m2 who underwent dual energy X-ray absorptiometry (DXA), high resolution peripheral quantitative computed tomography (HRpQCT), extended cortical analysis (ECA) and micro-finite element analysis (FEA) to obtain measures of volumetric bone mineral density (vBMD), bone geometry, microarchitecture, and strength estimates at the distal radius and tibia.

RESULTS

We found no differences between AA and W for total fat and lean mass, and areal BMD Z-scores (p > 0.05 for all). At the distal radius, no significant differences were detected in vBMD, bone geometry or microarchitecture (p > 0.05 for all); however, stiffness and failure load were higher in the AA group (p = 0.031 and 0.047 respectively). At the distal tibia, cortical vBMD was higher in AA vs. W (p = 0.012), while trabecular number was higher and trabecular separation lower in W vs. AA (p ≤ 0.028). Stiffness and failure load trended higher in AA vs. W (p = 0.052 and p = 0.048, respectively). Groups did not differ for any other bone parameter (p > 0.05).

CONCLUSION

Racial differences in bone endpoints appear to be less marked in those with moderate to severe obesity, suggesting that effects of obesity may blunt the effect of race on bone endpoints.

The Relation Between Calcaneus Stiffness Index as a Measure of Bone Density and Body Mass Index in an Egyptian Cohort

BACKGROUND

Obesity and osteoporosis are two conditions that are associated with morbidity and mortality; there is contradictory evidence regarding this association.

PURPOSE

The aim of the current study was to explore further the association between obesity and calcaneus stiffness index (CSI), as a measure of bone density, in a community-based cross-sectional study in an Egyptian population.

METHODS

A cross-sectional study was conducted among active subjects, aged ≥20 years old, over one year. CSI was measured by Quantitative ultrasound (QUS), in addition; QUS T-score and Z-score of the non-dominant heel scan were recorded.

RESULTS

Two hundred and eighty participants were recruited; 7 subjects were excluded because of Z score more than -2, mean age was 61 (± 11.9) years, and mean BMI was 29.7 (±5.6). Female participants were 77.7%, with mean of age 60.3 (± 11.6); and age range 20-82 years. Male participants were 22.3%, with mean of age 63.6 (± 12.7); and age range 30-80 years. Older subjects (>55 years) had significantly lower CSI and worse T-score than the younger subjects (P < 0.001 for both). In the younger age group, BMI was not significantly associated with CSI, even after adjustment for gender (P= 0.52). However, in the older age group, BMI was significantly associated with stiffness index (P= 0.049, O.R.= 1.73), even after adjustment for gender (P= 0.041, O.R.= 1.7).

CONCLUSION

Compared to young subjects, older subjects (≥55 years) had significantly lower bone strength as measured by CSI, and their BMI was significantly positively associated with bone density. In younger people (<55 years), BMI was not associated with bone strength.

Clinic, Anthropometric And Metabolic Changes In Adults With Class III Obesity Classified As Metabolically Healthy And Metabolically Unhealthy

PURPOSE

To describe clinical, biochemical and anthropometric profiles in adults with class III obesity classified as metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUHO).

PATIENTS AND METHODS

This is a cross-sectional study with patients classified as MHO and MUHO according to the NCEP-ATP III. Anthropometric, biochemical and clinical variables were analyzed.

RESULTS

A total of 223 subjects were evaluated and 32.73% were classified as MHO and 67.26% as MUHO, respectively. The insulin resistance homeostasis model (HOMA-IR) showed elevation in the MUHO group (p=0.003) and anthropometric variables were correlated with bone markers [body index mass (BMI) vs phosphorus: r=0.31, p<0.001; BMI vs 25(OH)D: r=-0.31, p=0.041]. Visceral adiposity index was lower in MHO (p=0.001). Negative correlations between inflammatory markers and bone markers were observed in the MHO group (calcium vs C-reactive protein: -0.30, p=0.017; parathyroid hormone vs HOMA-IR: r=-0.28, p=0.017.

CONCLUSION

MHO individuals showed important metabolic changes, such as those observed in MUHO, despite lower prevalence and severity. Continuous monitoring of these individuals is suggested, given the transient nature of the MHO phenotype.

Obesidade, Diabetes Mellitus tipo 2 e fragilidade óssea: uma revisão narrativa

Durante anos a obesidade foi vista como um fator protetor para fraturas e osteoporose. Diversos estudos, no entanto, contestam esta tese, descrevendo que a obesidade na verdade afeta negativamente o sistema esquelético, em especial a homeostase óssea, diminuindo a rigidez do tecido ósseo e aumentando o risco de fraturas. A obesidade e o diabetes estão frequentemente associados no mesmo paciente, e a compreensão da alteração do tecido ósseo nestas duas condições clínicas é fundamental para o melhor cuidado destes pacientes, principalmente devido ao risco aumentado de fraturas, que estão associadas a maior número de complicações no seu tratamento. O presente estudo, em revisão narrativa, descreve a relação entre obesidade e homeostase óssea, a fragilidade óssea nos pacientes obesos, diabéticos ou não, e a relação entre obesidade e fraturas.