From metabolic normality to cardiometabolic risk factors in subjects with obesity

Metabolically healthy obesity and risks of cardiovascular disease and all-cause mortality, a matched cohort study: the Shizuoka study

BACKGROUND

Metabolically healthy obesity is not always a benign condition. It is associated with an increased incidence of cardiovascular disease and all-cause mortality. We investigated the prognostic significance of metabolically healthy obesity by comparing clinical profile-matched metabolically healthy obesity and non-obesity groups.

METHODS

We analyzed a health insurance dataset with annual health checkup data from Japan. The analyzed data included 168,699 individuals aged <65 years. Obesity was defined as ≥25 kg/m2 body mass index. Metabolically healthy was defined as ≤1 metabolic risk factor (high blood pressure, low high-density lipoprotein cholesterol, high low-density lipoprotein cholesterol, or high hemoglobin A1c). Incidence rates of stroke, myocardial infarction, and all-cause mortality identified from the insurance data were compared between metabolically healthy obesity and non-obesity groups (n = 8644 each) using a log-rank test.

RESULTS

The stroke (obesity: 9.2 per 10,000 person-years; non-obesity: 10.5; log-rank test p = 0.595), myocardial infarction (obesity: 3.7; non-obesity: 3.1; p = 0.613), and all-cause mortality (obesity: 26.6; non-obesity: 23.2; p = 0.304) incidence rates did not differ significantly between the metabolically healthy obesity and non-obesity groups, even when the abdominal obesity was considered in the analysis. The lack of association was also observed in the comparison between the metabolically unhealthy obesity and non-obesity groups (n = 10,965 each). The population with metabolically healthy obesity reported negligibly worse metabolic profiles than the population with non-obesity at the 5.6-year follow-up.

CONCLUSION

Obesity, when accompanied by a healthy metabolic profile, did not increase the risk of cardiovascular outcomes and all-cause mortality.

From Beats to Metabolism: the Heart at the Core of Interorgan Metabolic Cross Talk

The heart, once considered a mere blood pump, is now recognized as a multifunctional metabolic and endocrine organ. Its function is tightly regulated by various metabolic processes, at the same time it serves as an endocrine organ, secreting bioactive molecules that impact systemic metabolism. In recent years, research has shed light on the intricate interplay between the heart and other metabolic organs, such as adipose tissue, liver, and skeletal muscle. The metabolic flexibility of the heart and its ability to switch between different energy substrates play a crucial role in maintaining cardiac function and overall metabolic homeostasis. Gaining a comprehensive understanding of how metabolic disorders disrupt cardiac metabolism is crucial, as it plays a pivotal role in the development and progression of cardiac diseases. The emerging understanding of the heart as a metabolic and endocrine organ highlights its essential contribution to whole body metabolic regulation and offers new insights into the pathogenesis of metabolic diseases, such as obesity, diabetes, and cardiovascular disorders. In this review, we provide an in-depth exploration of the heart's metabolic and endocrine functions, emphasizing its role in systemic metabolism and the interplay between the heart and other metabolic organs. Furthermore, emerging evidence suggests a correlation between heart disease and other conditions such as aging and cancer, indicating that the metabolic dysfunction observed in these conditions may share common underlying mechanisms. By unraveling the complex mechanisms underlying cardiac metabolism, we aim to contribute to the development of novel therapeutic strategies for metabolic diseases and improve overall cardiovascular health.

Metabolically healthy obesity: Misleading phrase or healthy phenotype?

Obesity is a heterogenous condition with multiple different phenotypes. Among these a particular subtype exists named as metabolically healthy obesity (MHO). MHO has multiple definitions and its prevalence varies according to study. The potential mechanisms underlying the pathophysiology of MHO include the different types of adipose tissue and their distribution, the role of hormones, inflammation, diet, the intestinal microbiota and genetic factors. In contrast to the negative metabolic profile associated with metabolically unhealthy obesity (MUO), MHO has relatively favorable metabolic characteristics. Nevertheless, MHO is still associated with many important chronic diseases including cardiovascular disease, hypertension, type 2 diabetes, chronic kidney disease as well as certain types of cancer and has the risk of progression into the unhealthy phenotype. Therefore, it should not be considered as a benign condition. The major therapeutic alternatives include dietary modifications, exercise, bariatric surgery and certain medications including glucagon-like peptide-1 (GLP-1) analogs, sodium-glucose cotransporter-2 (SGLT-2) inhibitors and tirzepatide. In this review, we discuss the significance of MHO while comparing this phenotype with MUO.

Transition from metabolically healthy to unhealthy overweight/obesity and risk of cardiovascular disease incidence: A systematic review and meta-analysis

AIMS

Discrepant results have been demonstrated regarding the cardiovascular (CV) risk of populations with metabolically healthy overweight/obesity (MHO) who were transitioned into metabolically unhealthy states. So, the objective of this systematic review and meta-analysis was to estimate the risk of cardiovascular diseases (CVD) incidence in individuals with transitional MHO phenotype.

DATA SYNTHESIS

A literature review was done in PubMed, Scopus, EMBASE, and google scholar databases. Pooled HRs for all fatal and nonfatal CV events were computed using random-effect models for transitional MHOs in general as well as for each sex subgroup separately. This systematic review and meta-analysis included a total of 7 prospective observational studies with a total of 7,720,165 participants, published between 2018 and 2020. The mean follow-up duration of participants was 11.7 (5.5) years. Overall, the transitional MHO individuals had a significant risk of CVD incidence [HR = 1.42, 95% CI (1.24-1.60)]. In addition, in both male and female subgroups, unstable MHO phenotype demonstrated a significant CVD risk and HRs for incident CVD in males and females were 1.51 (1.07-1.96) and 1.71 (1.08-2.34), respectively.

CONCLUSION

Transition from MHO to unhealthy state throughout follow-up elevated the risk of CVD in both male and female groups. This can explain the association between MHO and incidence of CV events especially with longer follow up period.

REGISTRATION CODE IN PROSPERO

CRD42021270225.

Female Sex and Angiotensin-Converting Enzyme (ACE) Insertion/Deletion Polymorphism Amplify the Effects of Adiposity on Blood Pressure

The pathophysiological link between adiposity and blood pressure is not completely understood, and evidence suggests an influence of sex and genetic determinants. We aimed to identify the relationship between adiposity and blood pressure, independent of a robust set of lifestyle and metabolic factors, and to examine the modulating role of sex and Angiotensin-Converting Enzyme (ACE) insertion/deletion (I/D) polymorphisms. In the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) study cohort, 1211 normotensive individuals, aged 30 to 60 years and followed-up after 3.3 years, were characterized for lifestyle and metabolic factors, body composition, and ACE genotype. Body mass index (BMI) and waist circumference (WC) were independently associated with mean arterial pressure, with a stronger relationship in women than men (BMI: r=0.40 versus 0.30; WC: r=0.40 versus 0.30, both P<0.01) and in individuals with the ID and II ACE genotypes in both sexes (P<0.01). The associations of BMI and WC with mean arterial pressure were independent of age, sex, lifestyle, and metabolic variables (standardized regression coefficient=0.17 and 0.18 for BMI and WC, respectively) and showed a significant interaction with the ACE genotype only in women (P=0.03). A 5 cm larger WC at baseline increased the risk of developing hypertension at follow-up only in women (odds ratio, 1.56 [95% CI, 1.15-2.10], P=0.004) and in II genotype carriers (odds ratio, 1.87 [95% CI, 1.09-3.20], P=0.023). The hypertensive effect of adiposity is more pronounced in women and in people carrying the II variant of the ACE genotype, a marker of salt sensitivity.

Metabolically healthy obesity and the risk of all-cause and cardiovascular disease mortality in a Korean population: a prospective cohort study

OBJECTIVES

This study aimed to examine the association between metabolically healthy obesity and all-cause and cardiovascular disease (CVD) mortality in a Korean population.

DESIGN

A prospective study.

SETTING

This study used data from the Korean Genome and Epidemiology Study.

PARTICIPANTS

A total of 140 137 participants were followed up over a median period of 9.2 years. Participants were categorised into four groups according to obesity (obese: body mass index ≥25 kg/m² or non-obese) and metabolic health (metabolically unhealthy: two or more metabolic abnormalities or metabolically healthy).

PRIMARY AND SECONDARY OUTCOME MEASURES

All-cause and CVD mortality of the participants until 31 December 2018 were ascertained by the National Health Insurance Service of beneficiary status of Korea.

RESULTS

Metabolically unhealthy non-obese participants were at elevated risk of all-cause mortality (HR, 1.12; 95% CI, 1.04 to 1.21; p=0.0019) and CVD mortality (HR, 1.39; 95% CI, 1.17 to 1.65; p=0.0002), particularly mortality from ischaemic heart disease (IHD) (HR, 1.54; 95% CI, 1.10 to 2.14; p=0.0116) compared with metabolically healthy non-obese participants. Surprisingly, metabolically healthy obese participants were at reduced risk of all-cause mortality (HR, 0.89; 95% CI, 0.81 to 0.98; p=0.0197). Metabolically unhealthy obese participants were at elevated risk of CVD mortality (HR, 1.51; 95% CI, 1.26 to 1.81; p<0.0001) and IHD mortality (HR, 1.88; 95% CI, 1.35 to 2.63; p=0.0002) compared with metabolically healthy non-obese participants.

CONCLUSIONS

In a Korean population, metabolically healthy obese participants had reduced risk of all-cause mortality compared with their non-obese counterparts, whereas metabolically unhealthy participants had elevated risk of CVD mortality, in particular mortality from IHD regardless of obesity.

Potential of Erythrocyte Membrane Lipid Profile as a Novel Inflammatory Biomarker to Distinguish Metabolically Healthy Obesity in Children

Metabolically healthy obesity (MHO) has been described as BMI ≥ 30 kg/m², without metabolic disorders traditionally associated with obesity. Beyond this definition, a standardized criterion, for adults and children, has not been established yet to explain the absence of those metabolic disorders. In this context, biomarkers of inflammation have been proposed as suitable candidates to describe MHO. The use of mature red blood cell fatty acid (RBC FA) profile is here proposed since its membrane lipidome includes biomarkers of pro- and anti-inflammatory conditions with a strict relationship with metabolic and nutritional status. An observational study was carried out in 194 children (76 children with obesity and 118 children with normal weight) between 6 and 16 years old. RBC FAs were analyzed by gas chromatography-flame ionization detector (GC-FID). An unsupervised hierarchical clustering method was conducted on children with obesity, based on the RBC FA profile, to isolate the MHO cluster. The MHO cluster showed FA levels similar to children with normal weight, characterized by lower values of arachidonic acid, (total ω-6 FA, ω6/ω3 FA ratios and higher values for EPA, DHA, and total ω-3 FA) (for all of them p ≤ 0.01) compared to the rest of the children with obesity (obese cluster). The MHO cluster also presented lipid indexes for higher desaturase enzymatic activity and lower SFA/MUFA ratio compared to the obese cluster. These differences are relevant for the follow-up of patients, also in view of personalized protocols providing tailored nutritional recommendations for the essential fatty acid intakes.

The association between transition from metabolically healthy obesity to metabolic syndrome, and incidence of cardiovascular disease: Tehran lipid and glucose study

Considering that the data available on the cardiovascular (CV) risk of metabolically healthy obesity phenotype, and the effect of transition to an unhealthy status are inconsistent, the aim of this study was to investigate the possible role of transition to unhealthy status among metabolically healthy overweight/obese (MHO) subjects on CVD incidence over a median follow-up of 15.9 years. In this large population-based cohort, 6758 participants (41.6% men) aged ≥ 20 years, were enrolled. Participants were divided into 4 groups based on their obesity phenotypes and follow-up results, including persistent metabolically healthy normal weight (MHNW), persistent MHO, transitional MHO and metabolically unhealthy overweight/obese (MUO). Metabolic health was defined as not having metabolic syndrome based on the Joint Interim Statement (JIS) criteria. Multivariable adjusted hazard ratios (HRs) were calculated for cardiovascular events. During follow-up, rate of CVD Incidence per 1000 person-years were 12 and 7 in males and females, respectively. Multivariable adjusted HRs (CI 95%) of CVD incidence among males and females were 1.37 (.78–2.41) and .85 (.34–2.15) in persistent MHO group, 1.55 (1.02–2.37) and .93 (.41–2.12) in transitional MHO group and 2.64 (1.89–3.70) and 2.65 (1.24–5.68) in MUO group. Our findings showed that CVD risk did not increase in the persistent MHO phenotype over a 15.9-year follow-up in both sexes. However, transition from MHO to MUO status during follow-up increased the CVD risk just in male individuals. Further studies are needed to provide conclusive evidence in favor of benign nature of transitional MHO phenotype in females.

Association of metabolically healthy obesity and elevated risk of coronary artery calcification: a systematic review and meta-analysis

Background

Metabolically healthy obesity (MHO) is defined as obesity with less than two parameters of metabolic abnormalities. Some studies report that MHO individuals show similar risk of cardiovascular disease (CVD) compared with metabolically healthy non-obese (MHNO) individuals, but the results are conflicting. Coronary artery calcium (CAC) reflects the extent of coronary atherosclerosis and is a useful tool to predict future risk of CVD. The objective of this meta-analysis was to investigate whether MHO is associated with elevated risk of CAC.

Method

We searched Cochrane, PubMed, and Embase up to April 19, 2019. Prospective cohort and cross-sectional studies examining the association between MHO subjects and CAC were included with MHNO as the reference. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using random-effect models. Subgroup analysis and meta-regression were applied to define possible sources of heterogeneity. We conducted this research following a pre-established protocol registered on PROSPERO (CRD 42019135006).

Results

A total of nine studies were included in this review and six studies with 23,543 participants were eligible for the meta-analysis. Compared with MHNO subjects, MHO had a higher odds of CAC (OR 1.36, 95% CI [1.11 to 1.66]; I² = 39%). In the subgroup analysis, the risk associated with MHO participants was significant in cohort studies (OR = 1.47, 95% CI [1.15,1.87], I² = 0%), and borderline significant in cross-sectional studies. The risk of CAC was also significant in MHO participants defined by Adult Treatment Panel III (ATP III) (OR = 1.55, 95% CI [1.25,1.93], I² = 0%). The univariate meta-regression model showed that age and smoking status were possible effect modifiers for MHO and CAC risk.

Conclusion

Our meta-analysis showed that MHO phenotypes were associated with elevated risk of CAC compared with MHNO, which reflects the extent of coronary atherosclerosis. People with obesity should strive to achieve normal weight even when only one metabolic abnormality is present.

Metabolically Healthy Obesity-Heterogeneity in Definitions and Unconventional Factors

The concept of heterogeneity among obese individuals in their risk for developing metabolic dysfunction and associated complications has been recognized for decades. At the origin of the heterogeneity idea is the acknowledgement that individuals with central obesity are more prone to developing type 2 diabetes and cardiovascular disease than those with peripheral obesity. There have been attempts to categorize subjects according to their metabolic health and degree of obesity giving rise to different obese and non-obese phenotypes that include metabolically unhealthy normal-weight (MUHNW), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO). Individuals belonging to the MHO phenotype are obese according to their body mass index although exhibiting fewer or none metabolic anomalies such as type 2 diabetes, dyslipidemia, hypertension, and/or unfavorable inflammatory and fribinolytic profiles. However, some authors claim that MHO is only transient in nature. Additionally, the phenotype categorization is controversial as it lacks standardized definitions possibly blurring the distinction between obesity phenotypes and confounding the associations with health outcomes. To add to the discussion, the factors underlying the origin or protection from metabolic deterioration and cardiometabolic risk for these subclasses are being intensely investigated and several hypotheses have been put forward. In the present review, we compare the different definitions of obesity phenotypes and present several possible factors underlying them (adipose tissue distribution and cellularity, contaminant accumulation on the adipose tissue, dysbiosis and metabolic endotoxemia imposing on to the endocannabinoid tone and inflammasome, and nutrient intake and dietary patterns) having inflammatory activation at the center.

Directional Relationship Between Vitamin D Status and Prediabetes: A New Approach from Artificial Neural Network in a Cohort of Workers with Overweight-Obesity

Objective: Despite the increasing literature on the association of diabetes with inflammation, cardiovascular risk, and vitamin D (25(OH)D) concentrations, strong evidence on the direction of causality among these factors is still lacking. This gap could be addressed by means of artificial neural networks (ANN) analysis.Methods: Retrospective observational study was carried out by means of an innovative data mining analysis-known as auto-contractive map (AutoCM)-and semantic mapping followed by Activation and Competition System on data of workers referring to an occupational-health outpatient clinic. Parameters analyzed included weight, height, waist circumference, body mass index (BMI), percentage of fat mass, glucose, insulin, glycated hemoglobin (HbA1c), creatinine, total cholesterol, low- and high-density lipoprotein cholesterol, triglycerides, uric acid, fibrinogen, homocysteine, C-reactive protein (CRP), diastolic and systolic blood pressure, and 25(OH)D.Results: The study included 309 workers. Of these, 23.6% were overweight, 40.5% were classified into the first class of obesity, 23.3% were in the second class, and 12.6% were in the third class (BMI > 40 kg/m ). All mean biochemical values were in normal range, except for total cholesterol, low- and high-density lipoprotein cholesterol, CRP, and 25(OH)D. HbA1c was between 39 and 46 mmol/mol in 51.78%. 25(OH)D levels were sufficient in only 12.6%. Highest inverse correlation for hyperglycemia onset was with BMI and waist circumference, suggesting a protective role of 25(OH)D against their increase. AutoCM processing and the semantic map evidenced direct association of 25(OH)D with high link strength (0.99) to low CRP levels and low high-density lipoprotein cholesterol levels. Low 25(OH)D led to changes in glucose, which affected metabolic syndrome biomarkers, first of which was homeostatic model assessment index and blood glucose, but not 25(OH)D.Conclusions: The use of ANN suggests a key role of 25(OH)D respect to all considered metabolic parameters in the development of diabetes and evidences a causation between low 25(OH)D and high glucose concentrations.

Do worse baseline risk factors explain the association of healthy obesity with increased mortality risk? Whitehall II Study

OBJECTIVE

To describe 20-year risk factor trajectories according to initial weight/health status and investigate the extent to which baseline differences explain greater mortality among metabolically healthy obese (MHO) individuals than healthy non-obese individuals.

METHODS

The sample comprised 6529 participants in the Whitehall II study who were measured serially between 1991-1994 and 2012-2013. Baseline weight (non-obese or obese; body mass index (BMI) ≥30 kg/m2) and health status (healthy or unhealthy; two or more of hypertension, low high-density lipoprotein cholesterol (HDL-C), high triglycerides, high glucose, and high homeostatic model assessment of insulin resistance (HOMA-IR)) were defined. The relationships of baseline weight/health status with 20-year trajectories summarizing ~25,000 observations of systolic and diastolic blood pressures, HDL-C, triglycerides, glucose, and HOMA-IR were investigated using multilevel models. Relationships of baseline weight/health status with all-cause mortality up until July 2015 were investigated using Cox proportional hazards regression.

RESULTS

Trajectories tended to be consistently worse for the MHO group compared to the healthy non-obese group (e.g., glucose by 0.21 (95% CI 0.09, 0.33; p < 0.001) mmol/L at 20-years of follow-up). Consequently, the MHO group had a greater risk of mortality (hazard ratio 2.11 (1.24, 3.58; p = 0.006)) when the referent group comprised a random sample of healthy non-obese individuals. This estimate, however, attenuated (1.34 (0.85, 2.13; p = 0.209)) when the referent group was matched to the MHO group on baseline risk factors.

CONCLUSIONS

Worse baseline risk factors may explain any difference in mortality risk between obese and non-obese groups both labelled as healthy, further challenging the concept of MHO.

Heterogeneity of obesity phenotypes in relation to cardiovascular risk

Obesity is associated with numerous metabolic disorders, the development and progression of a wide range of conditions and diseases, primarily cardiovascular disease and type 2 diabetes. One of the widely discussed phenomena of the association of obesity with cardiovascular diseases, their complications and mortality is the phenomenon of “heterogeneity of obesity phenotypes in relation to cardiovascular risk”. Currently, two main phenotypes have been identified — metabolically healthy and metabolically unhealthy obesity. At the same time, not only the expediency of separation, but also the existence of this phenotype is widely discussed today. The article provides an overview of existing approaches to the verification of metabolic phenotypes of obesity and data relating to the epidemiology and the association of metabolically healthy obesity with the risk of cardiovascular diseases and death, and also discusses the factors that determine the features of the obesity phenotype.

Heterogeneity of obesity phenotypes in relation to cardiovascular risk

Obesity is associated with numerous metabolic disorders, the development and progression of a wide range of conditions and diseases, primarily cardiovascular disease and type 2 diabetes. One of the widely discussed phenomena of the association of obesity with cardiovascular diseases, their complications and mortality is the phenomenon of “heterogeneity of obesity phenotypes in relation to cardiovascular risk”. Currently, two main phenotypes have been identified — metabolically healthy and metabolically unhealthy obesity. At the same time, not only the expediency of separation, but also the existence of this phenotype is widely discussed today. The article provides an overview of existing approaches to the verification of metabolic phenotypes of obesity and data relating to the epidemiology and the association of metabolically healthy obesity with the risk of cardiovascular diseases and death, and also discusses the factors that determine the features of the obesity phenotype.

Body size trajectories and cardio-metabolic resilience to obesity

Individuals with obesity do not represent a single homogenous group in terms of cardio‐metabolic health prospects. The concept of metabolically healthy obesity is a crude way of capturing this heterogeneity and has resulted in a plethora of research linking to future outcomes to show that it is not a benign condition. By contrast, very few studies have looked back in time and modelled the life course processes and exposures that explain the heterogeneity in cardio‐metabolic health and morbidity and mortality risk among people with the same body mass index (BMI) (or waist circumference or percentage body fat). The aim of the Medical Research Council New Investigator Research Grant (MR/P023347/1) ‘Body size trajectories and cardio‐metabolic resilience to obesity in three United Kingdom birth cohorts’ is to reveal the body size trajectories, pubertal development patterns and other factors (e.g. early‐life adversity) that might attenuate the positive associations of adulthood obesity makers (e.g. BMI) with cardio‐metabolic disease risk factors and other outcomes, thereby providing some degree of protection against the adverse effects of obesity. This work builds on the Principle Investigator's previous research as part of the Cohort and Longitudinal Studies Enhancement Resources initiative and focuses on secondary data analysis in the nationally representative UK birth cohort studies (initiated in 1946, 1958 and 1970), which have life course body size and exposure data and a biomedical sweep in adulthood. The grant will provide novel evidence on the life course processes and exposures that lead to some people developing a cardio‐metabolic complication or disease or dying while other people with the same BMI do not. This paper details the grant's scientific rationale, research objectives and potential impact.

Separate and combined associations of obesity and metabolic health with coronary heart disease: a pan-European case-cohort analysis

Aims

The hypothesis of 'metabolically healthy obesity' implies that, in the absence of metabolic dysfunction, individuals with excess adiposity are not at greater cardiovascular risk. We tested this hypothesis in a large pan-European prospective study.

Methods and results

We conducted a case-cohort analysis in the 520 000-person European Prospective Investigation into Cancer and Nutrition study ('EPIC-CVD'). During a median follow-up of 12.2 years, we recorded 7637 incident coronary heart disease (CHD) cases. Using cut-offs recommended by guidelines, we defined obesity and overweight using body mass index (BMI), and metabolic dysfunction ('unhealthy') as ≥ 3 of elevated blood pressure, hypertriglyceridaemia, low HDL-cholesterol, hyperglycaemia, and elevated waist circumference. We calculated hazard ratios (HRs) and 95% confidence intervals (95% CI) within each country using Prentice-weighted Cox proportional hazard regressions, accounting for age, sex, centre, education, smoking, diet, and physical activity. Compared with metabolically healthy normal weight people (reference), HRs were 2.15 (95% CI: 1.79; 2.57) for unhealthy normal weight, 2.33 (1.97; 2.76) for unhealthy overweight, and 2.54 (2.21; 2.92) for unhealthy obese people. Compared with the reference group, HRs were 1.26 (1.14; 1.40) and 1.28 (1.03; 1.58) for metabolically healthy overweight and obese people, respectively. These results were robust to various sensitivity analyses.

Conclusion

Irrespective of BMI, metabolically unhealthy individuals had higher CHD risk than their healthy counterparts. Conversely, irrespective of metabolic health, overweight and obese people had higher CHD risk than lean people. These findings challenge the concept of 'metabolically healthy obesity', encouraging population-wide strategies to tackle obesity.

The prevalence, metabolic risk and effects of lifestyle intervention for metabolically healthy obesity: a systematic review and meta-analysis: A PRISMA-compliant article

BACKGROUND

We conducted a systematic review and meta-analysis to firstly obtain a reliable estimation of the prevalence of metabolically healthy obese (MHO) individuals in obesity, then assessed the risk of developing metabolic abnormalities (MA) among MHO individuals. At last, we evaluated the effects of traditional lifestyle interventions on metabolic level for MHO subjects.

METHODS

A systematic review and meta-analysis (PRISMA) guideline were conducted, and original studies were searched up to December 31, 2016. The prevalence of MHO in obesity from each study was pooled using random effects models. The relative risks (RRs) were pooled to determine the risk of developing MA for MHO compared with metabolically healthy normal-weight (MHNW) subjects. For the meta-analysis of intervention studies, the mean difference and standardized mean differences were both estimated for each metabolic parameter within each study, and then pooled using a random-effects model.

RESULTS

Overall, 40 population-based studies reported the prevalence of MHO in obesity, 12 cohort studies and 7 intervention studies were included in the meta-analysis. About 35.0% obese individuals were metabolically healthy in the obese subjects. There were dramatic differences in the prevalence among different areas. However, 0.49 (95% confidence intervals [CI]: 0.38 to 0.60) of the MHO individuals would develop one or more MA within 10 years. Compared with MHNW subjects, the MHO subjects presented higher risk of incident MA (pooled RR = 1.80, 95%CI: 1.53-2.11). Following intervention, there was certain and significant improvement of metabolic state for metabolically abnormal obesity (MAO) subjects. Only diastolic blood pressure had reduced for MHO individuals after intervention.

CONCLUSIONS

Almost one-third of the obese individuals are in metabolic health. However, they are still at higher risk of advancing to unhealthy state. Therefore, it is still needed to advise MHO individuals to maintain or adopt a healthy lifestyle, so as to counterbalance the adverse effects of obesity.

Adipokines as atherothrombotic risk factors in obese subjects: Associations with haemostatic markers and common carotid wall thickness

BACKGROUND AND AIMS

Some crucial associations between obesity-related altered adipokine levels and the main factors of atherosclerotic, atherothrombotic processes are not fully known. We analysed the relationships of classic adipokines, namely leptin, resistin, adiponectin, tumour necrosis factor-alpha (TNF-α), interleukin 6 (IL-6) with the markers of platelet activation, including mean platelet volume (MPV), platelet surface/soluble P-selectin, platelet-derived microparticles (PMPs), the parameters of coagulation abnormalities and common carotid intima-media thickness (IMT) in obese patients with or without atherosclerotic comorbidities in comparison to age- and sex-matched controls.

METHODS AND RESULTS

We enrolled 154 obese individuals, including 98 suffering from atherosclerotic concomitant conditions, 56 free of atherosclerotic comorbidities and 62 healthy controls. Plasma levels of leptin, resistin, adiponectin, TNF-α, IL-6, soluble P-selectin, and plasminogen activator inhibitor-1 antigen (PAI-1 ag) were analysed by ELISA. Platelet surface P-selectin and PMPs were measured by flow cytometry. IMT was detected by ultrasonography. Adipokines were closely associated with markers of platelet hyperactivity, hypercoagulability, hypofibrinolysis and IMT. Significant independent associations were found between leptin and platelet count (p < 0.0001), MPV (p = 0.019), PMPs (p < 0.0001), fibrinogen (p = 0.001), factor VIII (FVIII) activity (p = 0.035); adiponectin and PAI-1 ag (p = 0.035); resistin and soluble P-selectin (p = 0.002); TNF-α and PAI-1 ag (p < 0.0001); and IL-6 and fibrinogen (p = 0.011). Finally, leptin (p = 0.0005), adiponectin (p = 0.019), IL-6 (p = 0.001), MPV (p = 0.0003), PMP (p = 0.008), and FVIII activity (p = 0.043) were independent predictors of IMT.

CONCLUSION

Overall, we suggest that in obese subjects altered adipokine levels play a key role in common carotid atherosclerosis both directly and through haemostatic parameters.

To be or not to be physically active: Insights for a real chance to have an appropriate body mass in a sample of teachers

BACKGROUND

Studies on the relationship between physical activity (PA) and being overweight/obese are inconclusive.

OBJECTIVE

The purpose of this study was to examine the prevalence of excess body weight (EBW) and its association with daily PA level in a sample of 1506 Brazilian teachers.

METHODS

The PA level was analyzed with the International Physical Activity Questionnaire and EBW was categorized as a body mass index (BMI) ≥25 kg/m2 and called 'overweight'. Chi-squared test and odds ratios (OR) were applied in the analysis.

RESULTS

The prevalence of persons who were overweight was lower as a function of higher PA levels and higher PA levels resulted in a lower prevalence of overweight for men and women, respectively. The authors found that for men, moderate (OR: 1.69; P = 0.03) and high (OR: 2.57; P = 0.002) PA levels were predictive for being in the normal body mass index (BMI) range. In women, a greater association of being in the normal BMI range was reported only for a moderate PA level (OR: 1.43; P = 0.004).

CONCLUSIONS

Higher daily PA levels are associated with being in the normal BMI range. To date, these findings will have important public health implications for an effective plan for the prevention of weight gain in Brazilian teachers.

Disability, Physical Inactivity, and Impaired Health-Related Quality of Life Are Not Different in Metabolically Healthy vs. Unhealthy Obese Subjects

BACKGROUND

Obesity represents a major health hazard, affecting morbidity, psychological status, physical functionality, quality of life, and mortality. The aim of the present study was to explore the differences between metabolically healthy (MHO) and metabolically unhealthy (MUO) obese subjects with regard to physical activity, disability, and health-related quality of life (HR-QoL).

METHODS

All subjects underwent a multidimensional evaluation, encompassing the assessment of body composition, metabolic biomarkers and inflammation, physical activity level (IPAQ questionnaire), disability (TSD-OC test), and HR-QoL (SF-36 questionnaire). MHO and MUO were defined based on the absence or the presence of the metabolic syndrome, respectively.

RESULTS

253 subjects were included (54 men and 199 women; age: 51.7 ± 12.8 vs. 50.3 ± 11.7 years, p = 0.46; BMI: 38.1 ± 5.7 vs. 38.9 ± 6.7 kg/m², p = 0.37). No significant difference was observed in body composition. There was no difference between MHO and MUO considering inflammation (hs-CRP: 6517.1 ± 11,409.9 vs. 5294.1 ± 5612.2 g/L; p = 0.37), physical inactivity (IPAQ score below 3000 METs-min/week in 77.6% of MHO vs. 80% of MUO subjects; p = 0.36), obesity-related disability (TSD-OC score > 33%, indicating a high level of obesity-related disability, in 20.2% of MHO vs. 26.5% of MUO subjects; p = 0.28), and the HR-QoL (SF-36 total score: 60 ± 20.8 vs. 62.8 ± 18.2, p = 0.27).

DISCUSSION AND CONCLUSION

The metabolic comorbidity and the impairment of functional ability and psycho-social functioning may have a different timing in the natural history of obesity. Alterations in the physical activity level and mobility disabilities may precede the onset of metabolic abnormalities. (Trial registration 2369 prot 166/12-registered 23 February 2012; Amendment 223/14-registered 13 February 2014).

Metabolic Syndrome Development During Aging with Special Reference to Obesity Without the Metabolic Syndrome

BACKGROUND

Obesity and its associated metabolic complications continue to increase worldwide. We investigated the development of metabolic syndrome (MetS) during aging in relation to body mass index (BMI) and exercise habits. We assigned special emphasis to the metabolic stability in individuals with obesity, but without MetS, a condition often referred to as metabolically healthy obesity.

MATERIALS AND METHODS

Cross-sectional analysis was carried out in a sample of 19,129 men and women aged 45-75 years from the EpiHealth study. In addition, longitudinal analyses were carried out in the ULSAM study (2322 men at baseline followed from age 50 to age 77) and in the PIVUS study (1016 men and women at baseline followed from age 70 to age 80). Participants were categorized into six groups according to BMI category (normal weight/BMI <25 kg/m², overweight/BMI 25-30 kg/m², and obesity/BMI >30 kg/m²) and MetS status (+/-, National Cholesterol Education Program criteria).

RESULTS

MetS prevalence and number of MetS components increased with age in all three samples. The PIVUS study showed that high baseline BMI, low baseline physical activity, and increasing BMI during follow-up were related to increasing MetS prevalence and increasing numbers of MetS components during follow-up. One-third to half of individuals initially belonging to the obesity without MetS category acquired MetS during aging.

CONCLUSIONS

MetS prevalence increased during aging, especially in individuals with high BMI, low level of physical activity, and weight gain. Obesity without MetS was not a stable condition over time as many of those individuals gained metabolic disturbances during aging.

"Metabolically healthy" obesity: Prevalence, clinical features and association with myocardial ischaemia

OBJECTIVE

To evaluate the prevalence of the "metabolically healthy" (MH) or "metabolically unhealthy" (MU) obesity phenotypes and their association with cardiorespiratory fitness and inducible myocardial ischaemia.

METHODS

Individuals without known coronary artery disease undergoing myocardial perfusion single-photon emission computed tomography (MPS) were studied. Those without dyslipidemia, hypertension, or diabetes were considered MH, and when ≥1 of these was present, MU status was considered present. Summed stress and difference perfusion scores (SSS and SDS, respectively) were calculated; a SDS >1 defined ischaemic MPS.

RESULTS

MH patients were 35.0% of the nonobese population and 23.5% of the obese (p<0.001). The prevalence of ischaemia was not significantly different between MH patients with obesity or MH patients without obesity (10.9% vs 9.1%, p=0.3), except for patients with body mass index ≥40kg/m² (21.9%). MH obese patients were less frequently able to exercise and had lower exercise capacity than the nonobese patients.

CONCLUSIONS

The prevalence of myocardial ischaemia was not significantly different between MH obese or nonobese individuals, supporting the concept of the "metabolically healthy obesity". However, there are other factors involved, such as the ability to exercise, that influence the risk of myocardial ischaemia, limiting the "safety" of that obesity phenotype.

Natural Course of Metabolically Healthy Overweight/Obese Subjects and the Impact of Weight Change

Few studies have described the characteristics of metabolically healthy individuals with excess fat in the Chinese population. This study aimed to prospectively investigate the natural course of metabolically healthy overweight/obese (MH-OW/OB) adults, and to assess the impact of weight change on developing metabolic abnormalities. During 2009–2010, 525 subjects without any metabolic abnormalities or other obesity-related diseases were evaluated and reevaluated after 5 years. The subjects were categorized into two groups of overweight/obese and normal weight based on the criteria of BMI by 24.0 at baseline. At follow-up, the MH-OW/OB subjects had a significantly increased risk of developing metabolically abnormalities compared with metabolically healthy normal-weight (MH-NW) individuals (risk ratio: 1.35, 95% confidence interval: 1.17–1.49, p value < 0.001). In the groups of weight gain and weight maintenance, the MH-OW/OB subjects was associated with a larger increase in fasting glucose, triglycerides, systolic blood pressure, diastolic blood pressure and decrease in high-density lipoprotein cholesterol comparing with MH-NW subjects. In the weight loss group, no significant difference of changes of metabolic parameters was observed between MH-OW/OB and MH-NW adults. This study verifies that MH-OW/OB are different from MH-NW subjects. Weight management is needed for all individuals since weight change has a significant effect on metabolic health without considering the impact of weight change according to weight status.

Does Metabolically Healthy Obesity Exist?

The relationship between obesity and other metabolic diseases have been deeply studied. However, there are clinical inconsistencies, exceptions to the paradigm of "more fat means more metabolic disease", and the subjects in this condition are referred to as metabolically healthy obese (MHO).They have long-standing obesity and morbid obesity but can be considered healthy despite their high degree of obesity. We describe the variable definitions of MHO, the underlying mechanisms that can explain the existence of this phenotype caused by greater adipose tissue inflammation or the different capacity for adipose tissue expansion and functionality apart from other unknown mechanisms. We analyze whether these subjects improve after an intervention (traditional lifestyle recommendations or bariatric surgery) or if they stay healthy as the years pass. MHO is common among the obese population and constitutes a unique subset of characteristics that reduce metabolic and cardiovascular risk factors despite the presence of excessive fat mass. The protective factors that grant a healthier profile to individuals with MHO are being elucidated.

A biopsychosocial approach to the interrelation between motherhood and women's excessive weight

Portugal is characterized by a high prevalence of overweight and obesity among women, whose weight increases most rapidly in early adulthood. Individual genetic features and behaviours, along with social, cultural and environmental factors interact in complex relationships with body weight and with its variation throughout time. Motherhood may trigger an increase in weight, potentially influencing the associations between excessive weight and several other health determinants. Taking into account the quality of prenatal care within Portugal's health care system, regarding coverage and success in improved outcomes, we theoretically demonstrate why pregnancy and motherhood should be seen as opportunities for prevention and why a deeper knowledge about the interplay of biological, social and psychological determinants of weight at this stage of life can be useful to design more effective weight control interventions towards this population.

Metabolically healthy obesity and cardiovascular events: A systematic review and meta-analysis

AIMS

Previous studies have provided inconsistent results about the cardiovascular risks for participants with metabolically healthy obesity (MHO). These uncertainties might partly reflect the lack of a uniform definition of MHO. We conducted a systematic review and meta-analysis to examine whether there is a suitable approach that identifies obese participants who are not at an increased risk of cardiovascular events compared with healthy normal-weight participants.

METHODS AND RESULTS

Twenty-two prospective studies were eligible for the meta-analysis. Using random-effect models, pooled relative risks (RRs) were calculated for the combined effects of obesity with the presence or absence of metabolic syndrome, insulin resistance, hypertension, diabetes, hyperlipidaemia and any of these metabolic factors. Participants with MHO defined by the absence of metabolic syndrome were at increased risk for cardiovascular events compared with healthy normal-weight participants (pooled RR 1.45, 95% confidence interval (CI) 1.20-1.70), but had lower risks than unhealthy normal-weight (RR 2.07, 95% CI 1.62-2.65) and obese (RR 2.31, 95% CI 1.99-2.69) participants. The risk associated with participants who had MHO was particularly high over the long term. Similar risk estimates were observed when MHO was defined by other approaches.

CONCLUSIONS

None of the approaches clearly identified an obese subgroup not at increased risk of cardiovascular events compared with normal-weight healthy participants. A benign obese phenotype might be defined by strict definitions, but insufficient studies exist to support this. More research is needed to better define MHO.

Metabolic Abnormalities Are Common among South American Hispanics Subjects with Normal Weight or Excess Body Weight: The CRONICAS Cohort Study

Objective

We aimed to characterize metabolic status by body mass index (BMI) status.

Methods

The CRONICAS longitudinal study was performed in an age-and-sex stratified random sample of participants aged 35 years or older in four Peruvian settings: Lima (Peru’s capital, costal urban, highly urbanized), urban and rural Puno (both high-altitude), and Tumbes (costal semirural). Data from the baseline study, conducted in 2010, was used. Individuals were classified by BMI as normal weight (18.5–24.9 kg/m²), overweight (25.0–29.9 kg/m²), and obese (≥30 kg/m²), and as metabolically healthy (0–1 metabolic abnormality) or metabolically unhealthy (≥2 abnormalities). Abnormalities included individual components of the metabolic syndrome, high-sensitivity C-reactive protein, and insulin resistance.

Results

A total of 3088 (age 55.6±12.6 years, 51.3% females) had all measurements. Of these, 890 (28.8%), 1361 (44.1%) and 837 (27.1%) were normal weight, overweight and obese, respectively. Overall, 19.0% of normal weight in contrast to 54.9% of overweight and 77.7% of obese individuals had ≥3 risk factors (p<0.001). Among normal weight individuals, 43.1% were metabolically unhealthy, and age ≥65 years, female, and highest socioeconomic groups were more likely to have this pattern. In contrast, only 16.4% of overweight and 3.9% of obese individuals were metabolically healthy and, compared to Lima, the rural and urban sites in Puno were more likely to have a metabolically healthier profile.

Conclusions

Most Peruvians with overweight and obesity have additional risk factors for cardiovascular disease, as well as a majority of those with a healthy weight. Prevention programs aimed at individuals with a normal BMI, and those who are overweight and obese, are urgently needed, such as screening for elevated fasting cholesterol and glucose.

Coronary artery disease risk among obese metabolically healthy young men

OBJECTIVE

The aim of this study was to assess coronary artery disease (CAD) risk among obese young men without metabolic risk factors.

DESIGN

A longitudinal study in a historical cohort.

METHODS

Incident CAD during a median follow-up of 6.1 years was assessed among 31,684 young men (mean age 31.2 ± 5.7 years) of the Metabolic, Lifestyle and Nutrition Assessment in Young Adults (MELANY) cohort. Participants were categorized by BMI and the number of metabolic abnormalities (based on the Adult Treatment Panel-III). Metabolically healthy (MH) obesity was defined as BMI ≥ 30 kg/m(2) in the presence of normal blood pressure (BP) and normal levels of fasting glucose, triglyceride, and HDL-cholesterol (HDL-c) levels (n = 599; 1.9%). Cox proportional hazard models were applied.

RESULTS

There were 198 new cases of CAD that were diagnosed during 209,971 person-years of follow-up, of which six cases occurred among MH obese. The incidence of CAD among MH lean, overweight, and obese participants was 0.23, 0.45, and 1.0/1000 person-years respectively. In a multivariable model adjusted for clinical and biochemical CAD risk factors, a higher CAD risk was observed among MH-obese (hazard ratio = 3.08; 95% CI = 1.10-8.68, P = 0.033), compared to MH-normal weight subjects. This risk persisted when BMI was treated as a time-dependent variable, or when fasting glucose, HDL-c, triglycerides, or BP were added to the model. Similar results were also obtained when a more permissive definition of MH was used.

CONCLUSIONS

Obesity may continue to contribute to increased risk for incident CAD in young men even in the presence of a healthy metabolic profile.

Association between metabolically unhealthy overweight/obesity and chronic kidney disease: the role of inflammation

AIM

Our study explored the association between subtypes of increased fat mass (with or without associated metabolic alterations) and the presence of chronic kidney disease (CKD).

METHODS

In this cross-sectional survey in China, body mass index (BMI) was used to assess fat mass. Metabolically healthy was defined as no insulin resistance or any metabolic syndrome components except abdominal obesity. We also used two previous definitions of metabolically healthy. Multiple logistic regression models were used. Normal weight with metabolic health was designated the reference group. Three other subgroups included normal weight with metabolic unhealthiness, overweight/obesity with metabolic health and overweight/obesity with metabolic unhealthiness.

RESULTS

Of the 2324 subjects, 11.77% overweight/obese subjects were metabolically healthy. Compared with normal-weight subjects who were metabolically healthy, overweight/obese subjects who were metabolically healthy did not have an increased risk of CKD (OR: 0.79, 95% CI: 0.29–2.14; P = 0.64), whereas overweight/obese subjects who were metabolically unhealthy had a significantly higher risk of CKD (OR: 2.47, 95% CI: 1.5–3.95; P < 0.001). Normal-weight subjects who were metabolically unhealthy also had a higher risk of CKD, but the P value was of borderline significance. On further adjusting for C-reactive protein (CRP) levels, ORs were much attenuated, but did not alter the associations observed. Using two other definitions of metabolically healthy resulted in similar results.

CONCLUSION

Metabolically unhealthy overweight/obesity, but not metabolically healthy overweight/obesity, is associated with an increased risk of CKD. Inflammation might mediate at least part of the association between metabolic changes and CKD prevalence.

Healthy excessive weight in Portuguese women 4 years after delivery of a liveborn

OBJECTIVE

To quantify the prevalence of healthy excessive weight and determinants of metabolic profile, considering women's reproductive life.

METHODS

We evaluated 1847 mothers of a birth cohort assembled after delivery and reevaluated 4years later. A healthy profile was defined as the absence of hypertension, diabetes, dyslipidemia, C-reactive protein <3mg/l and being below the second tertile of HOMA-IR. Adjusted odds ratios (OR) and confidence intervals (95% CI) were computed using multinomial logistic regression, taking women with normal BMI as the reference category of the outcome.

RESULTS

Four years after delivery, 47% of women had normal BMI, 33% were overweight and 20% obese. In each BMI class, 61%, 33% and 12% presented a healthy metabolic profile, respectively. Family history of CVD/cardiometabolic risk factors was associated with a higher probability of obesity with a not healthy metabolic profile (OR=1.39 95% CI: 0.98-1.98). Women who breastfed the enrolled child for >26weeks and practiced physical exercise were less likely to be obese and metabolically unhealthy (OR=0.39 95% CI: 0.23-0.68; OR=0.48 95% CI: 0.33-0.70, respectively), with no effect on healthy excessive weight.

CONCLUSIONS

These results support the existence of a healthy excessive weight phenotype in women after motherhood, influenced by anthropometrics, genetic and lifestyles characteristics.

Main characteristics of metabolically obese normal weight and metabolically healthy obese phenotypes

In this review, the influence of fat depots on insulin resistance and the main characteristics of metabolically obese normal-weight and metabolically healthy obese phenotypes are discussed. Medline/PubMed and Science Direct were searched for articles related to the terms metabolically healthy obesity, metabolically obese normal weight, adipose tissue, and insulin resistance. Normal weight and obesity might be heterogeneous in regard to their effects. Fat distribution and lower insulin sensitivity are the main factors defining phenotypes within the same body mass index. Although these terms are interesting, controversies about them remain. Future studies exploring these phenotypes will help elucidate the roles of adiposity and/or insulin resistance in the development of metabolic alterations.

RELATIVE CONTRIBUTIONS OF ECTOPIC LIVER AND ABDOMINAL FAT ACCUMULATION TO ARTERIAL STIFFNESS

OBJECTIVE

To compare the arterial stiffness between the abdominal obese population without nonalcoholic fatty liver disease (NAFLD) (referred to as abdominal fat accumulation), the normal-weight population with NAFLD (ectopic liver fat accumulation), and the population with both abdominal obesity and NAFLD (accumulation of both abdominal and ectopic liver fat).

METHODS

A total of 111,552 Chinese adults who underwent the health checkups from January 2012 to December 2012 were screened. Clinical and biochemical parameters were measured in each subject. NAFLD was diagnosed by ultrasonography. Arterial stiffness was evaluated by cardio-ankle vascular index (CAVI).

RESULTS

Normal-weight subjects with NAFLD had significantly higher CAVI than subjects with abdominal obesity with or without NAFLD (8.12 ± 1.16 vs. 7.93 ± 1.38, 7.96 ± 1.20; P<.01). When the presence of abdominal obesity, NAFLD, and both diseases (abdominal obesity and NAFLD) were included in regression analyses individually, CAVI was independently associated with abdominal obesity or NAFLD or both after adjusting for confounders. When the presence of abdominal obesity and NAFLD and both diseases were included simultaneously in regression analyses, the association between NAFLD and CAVI and the association between both diseases and CAVI remained significant, whereas the association between abdominal obesity and CAVI was no longer significant. The presence of NAFLD conferred a greater odds ratios of having an elevated CAVI than did the presence of abdominal obesity or even the presence of both diseases.

CONCLUSION

Ectopic liver fat accumulation is associated with greater risk of arterial stiffness compared with abdominal fat accumulation or accumulation of both abdominal and ectopic liver fat.

Subclinical atherosclerosis determinants in morbid obesity

BACKGROUND AND AIMS

Obesity is associated with increased cardiovascular risk. However, the impact of morbid obesity on vascular structure and function is not well understood. This study was designed to appraise subclinical atherosclerosis markers, including carotid intima media thickness (cIMT), endothelial function, and arterial wall stiffness, and their determinants, in morbidly obese patients.

METHODS AND RESULTS

In this cross-sectional study 194 overweight and obese patients were distributed in morbid-obese patients (MOP, n = 110), obese (OP, n = 84) and overweight patients (OwP, n = 33) groups. Demography, anthropometry, clinical and standard biochemical data were recorded. cIMT, endothelial function, defined as the small artery reactivity index (saRHI), and artery wall rigidity, studied by the augmentation index, were determined. More than 50% of the MOP, OP and OwP had a cIMT above the 75th percentile per age and gender. No differences in cIMT or saRHI were observed, although overweight and obese patients (OOP) had higher arterial rigidity compared with the morbid-obese patients. In a multivariate regression test, while cholesterol was the main determinant of cIMT in overweight and obese patients, glucose metabolism was the determinant in MOP.

CONCLUSION

More than half of the population have a cIMT above general population ranges. OwP, OP and MOP have similar cIMT and saRHI. However, OOP have greater arterial wall rigidity. Dysglycemia is the main factor associated with subclinical atherosclerosis in MOP.

Metabolically healthy obesity from childhood to adulthood - Does weight status alone matter?

Up to 30% of obese people do not display the "typical" metabolic obesity-associated complications. For this group of patients, the term "metabolically healthy obese (MHO)" has been established during the past years and has been the focus of research activities. The development and severity of insulin resistance as well as (subclinical) inflammations seems to play a key role in distinguishing metabolically healthy from metabolically non-healthy individuals. However, an internationally consistent and accepted classification that might also include inflammatory markers as well as features of non-alcoholic fatty liver disease is missing to date, and available data - in terms of prevalence, definition and severity - are heterogeneous, both during childhood/adolescence and during adulthood. In addition, the impact of MHO on future morbidity and mortality compared to obese, metabolically non-healthy as well as normal weight, metabolically healthy individuals is absolutely not clear to date and even conflicting. This review summarizes salient literature related to that topic and provides insight into our current understanding of MHO, covering all age spans from childhood to adulthood.

All-cause mortality risk of metabolically healthy abdominal obese individuals: the EPIC-MORGEN study

OBJECTIVE

It appears that a certain proportion of obese individuals have a normal metabolic profile despite having excess weight. Whether these so-called "metabolically healthy" obese express lower disease and mortality risks than "metabolically unhealthy" obese is still unclear. The mortality risk of "metabolically healthy" abdominal obese (MHAO) individuals was investigated.

DESIGN AND METHODS

Prospective cohort study (EPIC-MORGEN) among 22,654 individuals aged 20-59 years followed for an average of 13.4 years (SD 2.3). MHAO was assessed at baseline (1993-1997) and defined as abdominal obesity (waist circumference ≥102 cm/≥88 cm (men/women)) with normal glucose, blood pressure, and plasma lipids. All-cause mortality risks adjusted for age and sex were estimated using Cox proportional hazards models.

RESULTS

Individuals who were "metabolically healthy" nonabdominal obese (MHNAO) comprised the reference group. As compared to MHNAO, mortality risk for MHAO was around 40% higher (Hazard ratio (HR) 1.43; 95% confidence interval (CI): 1.00-2.04) and of the same magnitude as that for "metabolically unhealthy" nonabdominal obese (MUNAO) (HR 1.31; 95% CI: 1.08-1.59). The HR for MUAO was 1.99 (95% CI: 1.62-2.43).

CONCLUSIONS

Mortality risk of MHAO individuals was significantly higher than that of MHNAO individuals and lower than, but not statistically significantly different from, that of MUAO individuals.

Beyond BMI: The "Metabolically healthy obese" phenotype & its association with clinical/subclinical cardiovascular disease and all-cause mortality -- a systematic review

Background

A subgroup has emerged within the obese that do not display the typical metabolic disorders associated with obesity and are hypothesized to have lower risk of complications. The purpose of this review was to analyze the literature which has examined the burden of cardiovascular disease (CVD) and all-cause mortality in the metabolically healthy obese (MHO) population.

Methods

Pubmed, Cochrane Library, and Web of Science were searched from their inception until December 2012. Studies were included which clearly defined the MHO group (using either insulin sensitivity and/or components of metabolic syndrome AND obesity) and its association with either all cause mortality, CVD mortality, incident CVD, and/or subclinical CVD.

Results

A total of 20 studies were identified; 15 cohort and 5 cross-sectional. Eight studies used the NCEP Adult Treatment Panel III definition of metabolic syndrome to define “metabolically healthy”, while another nine used insulin resistance. Seven studies assessed all-cause mortality, seven assessed CVD mortality, and nine assessed incident CVD. MHO was found to be significantly associated with all-cause mortality in two studies (30%), CVD mortality in one study (14%), and incident CVD in three studies (33%). Of the six studies which examined subclinical disease, four (67%) showed significantly higher mean common carotid artery intima media thickness (CCA-IMT), coronary artery calcium (CAC), or other subclinical CVD markers in the MHO as compared to their MHNW counterparts.

Conclusions

MHO is an important, emerging phenotype with a CVD risk between healthy, normal weight and unhealthy, obese individuals. Successful work towards a universally accepted definition of MHO would improve (and simplify) future studies and aid inter-study comparisons. Usefulness of a definition inclusive of insulin sensitivity and stricter criteria for metabolic syndrome components as well as the potential addition of markers of fatty liver and inflammation should be explored. Clinicians should be hesitant to reassure patients that the metabolically benign phenotype is safe, as increased risk cardiovascular disease and death have been shown.

Relationship of race-ethnicity, body mass index, and economic strain with longitudinal self-report of physical functioning: the Study of Women's Health Across the Nation

PURPOSE

This study examined progression and improvement of physical functioning limitations during the mid-life and whether race-ethnicity, economic strain, or body mass index were associated with these changes.

METHODS

Women from the Study of Women's Health Across the Nation with one or more measure of self-reported physical functioning, categorized as no, some, or substantial limitations, between study visits 4 and 12 were included (n = 2497).

RESULTS

When women were aged 56-66 years, almost 50% reported limitations in functioning. African American women were more likely to report substantial (odds ratio, 1.63; 95% confidence interval, 1.06-2.52) and Chinese women were more likely to report some limitations (odds ratio, 2.03; 95% CI, 1.22-3.36) compared with Caucasian women. Economic strain and obesity predicted limitations. The probability of worsening ranged from 6% to 22% and of improving ranged from 11% to 30%. Caucasian and Japanese women had the highest probability of remaining fully functional (80% and 84%, respectively) compared with 71% of African American women.

CONCLUSIONS

Race-ethnicity, obesity, and economic strain were associated with prevalence and onset of physical functioning limitations. Functional improvement is common, even among vulnerable subgroups of women. Future studies should characterize predictors of decline and improvement so that interventions can sustain functioning even in the context of many known immutable risk factors.