Associations of metabolic changes and polygenic risk scores with cardiovascular outcomes and all-cause mortality across BMI categories: a prospective cohort study.

BACKGROUND: Associations between metabolic status and metabolic changes with the risk of cardiovascular outcomes have been reported. However, the role of genetic susceptibility underlying these associations remains unexplored. We aimed to examine how metabolic status, metabolic transitions, and genetic susceptibility collectively impact cardiovascular outcomes and all-cause mortality across diverse body mass index (BMI) categories. METHODS: In our analysis of the UK Biobank, we included a total of 481,576 participants (mean age: 56.55; male: 45.9%) at baseline. Metabolically healthy (MH) status was defined by the presence of < 3 abnormal components (waist circumstance, blood pressure, blood glucose, triglycerides, and high-density lipoprotein cholesterol). Normal weight, overweight, and obesity were defined as 18.5 ≤ BMI < 25 kg/m2, 25 ≤ BMI < 30 kg/m2, and BMI ≥ 30 kg/m2, respectively. Genetic predisposition was estimated using the polygenic risk score (PRS). Cox regressions were performed to evaluate the associations of metabolic status, metabolic transitions, and PRS with cardiovascular outcomes and all-cause mortality across BMI categories. RESULTS: During a median follow-up of 14.38 years, 31,883 (7.3%) all-cause deaths, 8133 (1.8%) cardiovascular disease (CVD) deaths, and 67,260 (14.8%) CVD cases were documented. Among those with a high PRS, individuals classified as metabolically healthy overweight had the lowest risk of all-cause mortality (hazard ratios [HR] 0.70; 95% confidence interval [CI] 0.65, 0.76) and CVD mortality (HR 0.57; 95% CI 0.50, 0.64) compared to those who were metabolically unhealthy obesity, with the beneficial associations appearing to be greater in the moderate and low PRS groups. Individuals who were metabolically healthy normal weight had the lowest risk of CVD morbidity (HR 0.54; 95% CI 0.51, 0.57). Furthermore, the inverse associations of metabolic status and PRS with cardiovascular outcomes and all-cause mortality across BMI categories were more pronounced among individuals younger than 65 years (Pinteraction < 0.05). Additionally, the combined protective effects of metabolic transitions and PRS on these outcomes among BMI categories were observed. CONCLUSIONS: MH status and a low PRS are associated with a lower risk of adverse cardiovascular outcomes and all-cause mortality across all BMI categories. This protective effect is particularly pronounced in individuals younger than 65 years. Further research is required to confirm these findings in diverse populations and to investigate the underlying mechanisms involved.

Acute ischemic stroke in young adults: comparative analysis of outcomes and mortality in metabolically healthy obese or overweight vs. non-obese or overweight hospitalizations, 2016-2019 cohort.

INTRODUCTION: Rising obesity rates and the increasing prevalence of stroke in the metabolically healthy obese and overweight (MHOO) necessitate examining its association in younger (18-44 year) populations and analyzing acute ischemic stroke (AIS) trends and outcomes in MHOO vs. metabolically healthy non-obese or overweight (MHnOO). METHODS: Data from the United States National Inpatient Sample (2016-2019) was analyzed to identify young MHOO and MHnOO AIS patients using ICD-10-CM codes. Metabolically healthy status was defined by excluding hospitalization records with diagnostic codes for hypertension, diabetes, and dyslipidemia. Demographics, trends, and outcomes were compared using appropriate statistical approaches. RESULTS: Of 26,949,310 young metabolically healthy hospitalizations between 2016 and 2019, 47,795 had AIS, of which 4,985 were MHOO and 42,810 were MHnOO. The median age of AIS hospitalization was 35 years, and primarily female and white. From 2016 to 2019, AIS incidence rose slightly, which was significant only for the MHnOO cohort. The in-hospital mortality rate was significantly lower in the MHOO cohort (6.0 % vs. 8.6 %, p < 0.001). Hospitalization length and cost did not differ substantially between groups. Adjusted multivariable analysis revealed no significant difference in AIS hospitalization risk between MHOO and MHnOO (aOR: 1.02, p=0.701), with subgroup analysis in males (aOR: 0.88, p=0.161) or females (aOR: 1.06, p=0.363). However, all-cause in-hospital mortality (ACIHM) in AIS had lower odds in the MHOO vs. MHnOO cohorts (aOR: 0.60, p=0.021). CONCLUSION: Our study finds a rising trend of AIS hospitalizations in young metabolically healthy adults, with obesity or overweight status not being associated with AIS hospitalization. We identify an "obesity paradox" of lower odds for ACIHM for AIS hospitalizations in the MHOO cohort.

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.

Impact of the Definition of Metabolically Healthy Obesity on the Association with Incident Cardiovascular Disease.

Background: Whether subjects with metabolically healthy obesity (MHO) have an increased risk of cardiovascular disease (CVD) is controversial. Some of this discrepancy could be due to differences in the definition of MHO. Therefore, we investigated how the definition of MHO affected the risk of CVD. Methods: In the Uppsala Longitudinal Study of Adult Men (ULSAM) cohort (total n = 2122, mean age 50 years), obese (n = 134), overweight (n = 845), and normal weight (n = 1143) individuals were subdivided according to the number of Metabolic Syndrome (MetS) risk factors (excluding waist circumference). During a median follow-up of 28.0 years, 877 individuals experienced a CVD event (defined as fatal or nonfatal myocardial infarction, stroke, or heart failure). Results: All obese groups, except that without any MetS risk factors (n = 3), showed an increased risk compared to the control group of normal weight without any MetS risk factors (n = 235), ranging from a hazard ratio (HR) of 3.0 (95% confidence interval [CI] 1.7-5.3, P = 0.0002) in those with one MetS risk factor to HR 5.5 (95% CI 3.0-9.8, P < 0.00001) in those with four MetS risk factors. The overweight group without any MetS risk factor (n = 74) showed a similar risk of incident CVD as the normal weight group, whereas all other overweight groups showed an increased risk with increasing number of MetS risk factors. Conclusions: The results suggest that the definition of MHO played a major role on the risk of CVD. No increased risk was seen in overweight/obese individuals with no MetS risk factor, but they were very rare.

The Association between Metabolically Healthy Obesity, Cardiovascular Disease, and All-Cause Mortality Risk in Asia: A Systematic Review and Meta-Analysis.

We investigated the association among metabolically healthy obesity (MHO), cardiovascular disease (CVD)risk, and all-cause mortality in the Asian population. We searched databases from inception to 16 November, 2019 and pooled data using a random-effects model. Subgroup analysis was conducted according to the following comparison groups: MHNW (without overweight or underweight participants) and MHNO (non-obese, including overweight and underweight participants). Nineteen studies were included. The mean Newcastle-Ottawa Scale score was 7.8. Participants with MHO had a significantly higher CVD risk (odds ratio (OR) = 1.36, 95% confidence interval (CI) = 1.13-1.63) and significantly lower risk of all-cause mortality (OR = 0.88, 95% CI = 0.78-1.00) than the comparison group. Subgroup analyses revealed participants with MHO had a significantly higher CVD risk than MHNW participants (OR = 1.61; 95% CI = 1.24-2.08; I2 = 73%), but there was no significant difference compared with MHNO participants (OR, 1.04; 95% CI, 0.80-1.36; I2 = 68%). Participants with MHO had a significantly lower risk of all-cause mortality (OR = 0.83; 95% CI = 0.78-0.88; I2 = 9%) than MHNO participants, but a borderline significantly higher risk of all-cause mortality than MHNW participants (OR = 1.30; 95% CI = 0.99-1.72; I2 = 0%). The CVD risk and all-cause mortality of the MHO group changed depending on the control group. Thus, future studies should select control groups carefully.

Metabolically healthy obesity and risk of cardiovascular disease, cancer, and all-cause and cause-specific mortality: a protocol for a systematic review and meta-analysis of prospective studies.

INTRODUCTION: Metabolically healthy obese phenotype (MHO) refers to obese individuals with an adequate metabolic profile and absence of metabolic syndrome. Many prospective studies have reported the benign condition relating the MHO phenotype and its potential role in reducing risk of cardiovascular disease, total cancer, and all-cause and cause-specific mortality. However, inconsistent results were found and the question remains controversial. We aim to conduct a systematic review and meta-analysis to clarify the associations these associations from relevant prospective studies. METHODS AND ANALYSIS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Protocols 2015 statement was used to prepare this protocol. MEDLINE, Web of Science databases, EMBASE and Cochrane Database will be used for literature search from their inception up to December 2019 with restriction of published studies in English. Published prospective studies reporting adjusted relative risk (RR) estimates for the association between MHO phenotype and cardiovascular disease, total cancer, all-cause or cause-specific mortality will be included. The process of study screening, selection and data extraction will be performed independently by two reviewers, and the risk of bias for the studies included will be assessed using the Newcastle-Ottawa Quality Assessment Scale. HRs or RRs for disease events and mortality with 95% CIs will be considered as primary outcomes, and summary HRs/RRs will be pooled using random-effects models. The Cochrane's Q and the I2 statistics will be used to assess and quantify heterogeneity, respectively. Subgroup analysis will also be carried out according to study characteristics to investigate potential sources of heterogeneity. ETHICS AND DISSEMINATION: As this meta-analysis is performed based on the published studies, no ethical approval and patient safety considerations are required. The findings of the study will be reported and submitted to a peer-reviewed journals for publication. PROSPERO REGISTRATION NUMBER: CRD42019121766.

Metabolically healthy obesity: facts and fantasies.

Although obesity is typically associated with metabolic dysfunction and cardiometabolic diseases, some people with obesity are protected from many of the adverse metabolic effects of excess body fat and are considered "metabolically healthy." However, there is no universally accepted definition of metabolically healthy obesity (MHO). Most studies define MHO as having either 0, 1, or 2 metabolic syndrome components, whereas many others define MHO using the homeostasis model assessment of insulin resistance (HOMA-IR). Therefore, numerous people reported as having MHO are not metabolically healthy, but simply have fewer metabolic abnormalities than those with metabolically unhealthy obesity (MUO). Nonetheless, a small subset of people with obesity have a normal HOMA-IR and no metabolic syndrome components. The mechanism(s) responsible for the divergent effects of obesity on metabolic health is not clear, but studies conducted in rodent models suggest that differences in adipose tissue biology in response to weight gain can cause or prevent systemic metabolic dysfunction. In this article, we review the definition, stability over time, and clinical outcomes of MHO, and discuss the potential factors that could explain differences in metabolic health in people with MHO and MUO - specifically, modifiable lifestyle factors and adipose tissue biology. Better understanding of the factors that distinguish people with MHO and MUO can produce new insights into mechanism(s) responsible for obesity-related metabolic dysfunction and disease.

Metabolically healthy versus metabolically unhealthy obesity.

Obesity-related disease complications reduce life quality and expectancy and increase health-care costs. Some studies have suggested that obesity not always entails metabolic abnormalities and increased risk of cardiometabolic complications. Because of the lack of universally accepted criteria to identify metabolically healthy obesity (MHO), its prevalence varies widely among studies. Moreover, the prognostic value of MHO is hotly debated, mainly because it likely shifts gradually towards metabolically unhealthy obesity (MUO). In this review, we outline the differential factors contributing to the metabolic heterogeneity of obesity by discussing the behavioral, genetic, phenotypical, and biological aspects associated with each of the two metabolic phenotypes (MHO and MUO) of obesity and their clinical implications. Particular emphasis will be laid on the role of adipose tissue biology and function, including genetic determinants of body fat distribution, depot-specific fat metabolism, adipose tissue plasticity and, particularly, adipogenesis. Finally, the emerging role of gut microbiota in obesity and adipose tissue dysfunction as well as the search for novel biomarkers for the obesity-related metabolic traits and associated diseases will be briefly presented. A better understanding of the main determinants of a healthy metabolic status in obesity would allow promotion of this favorable condition by targeting the relevant pathways.

Metabolically healthy obesity, vitamin D, and all-cause and cardiometabolic mortality risk in NHANES III.

BACKGROUND & AIMS: Previous studies assessing the prognosis of metabolically healthy obesity (MHO) have been limited by a lack of a harmonized definition of MHO phenotype. Furthermore, obesity is a risk factor for vitamin D deficiency and low vitamin D status has been associated with a higher risk of mortality; however, few studies have evaluated the joint association between vitamin D, metabolic health phenotype, and mortality risk. Using a harmonized definition, we investigated whether MHO is associated with subsequent all-cause and cardiometabolic mortality, and whether serum 25-hydroxyvitamin D [25(OH)D] modifies these associations. METHODS: This study included participants aged ≥20 years from the Third National Health and Nutrition Examination Survey (NHANES III). MHO phenotype was defined as a combination of obesity (≥30 kg/m2) and zero component of metabolic syndrome. Multivariable Cox regression was used to assess the risk of mortality across metabolic phenotypes, and the joint association between metabolic phenotype and 25(OH)D. Fine and Gray regression was performed to account for competing risk events. RESULTS: Among 11,333 participants, a total of 2980 deaths (937 cardiometabolic death outcomes) occurred during a median follow-up of 19.1 years. In the absence of any metabolic abnormality, obesity (MHO) was not associated with a higher risk of all-cause (hazard ratio [HR], 0.89 [95% CI, 0.52-1.51]) or cardiometabolic mortality (cause-specific HR, 1.21 [95% CI 0.33-4.46]). Similar results were obtained from competing risk analysis. No significant differences in average 25(OH)D levels were observed between MHO and non-MHO participants; however, there was a significant interaction between metabolic health phenotype and serum 25(OH)D in relation to cardiometabolic mortality such that levels of serum 25(OH)D < 50 nmol/L were associated with increased risk of cardiometabolic mortality, particularly in participants within the normal-weight and obese BMI ranges. CONCLUSIONS: Our results support the hypothesis that MHO phenotype is a benign health condition. Vitamin D deficiency may exacerbate the risk of cardiometabolic death outcomes associated with metabolic dysfunction in normal weight and obese individuals. Further research is warranted to validate our findings.

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.

Obesity and the Obesity Paradox in Heart Failure.

Obesity continues to be a public health problem in the general population, and also significantly increases the risk for the development of new-onset heart failure (HF). However, in patients with already-established, chronic HF, overweight and mild to moderate obesity is associated with substantially improved survival compared to normal weight patients; this has been termed the "obesity paradox". The majority of studies measure obesity by body mass index, but studies utilizing less-frequently used measures of body fat and body composition, including waist circumference, waist-hip ratio, skinfold estimates, and bioelectrical impedance analysis also confirm the obesity paradox in HF. Other areas of investigation such as the relationship of the obesity paradox to cardiorespiratory fitness, gender, and race are also discussed. Finally, this review explores various explanations for the obesity paradox, and summarizes the current evidence for intentional weight loss treatments for HF in context.

Metabolically Healthy Obesity, Transition to Metabolic Syndrome, and Cardiovascular Risk.

BACKGROUND: Debate over the cardiometabolic risk associated with metabolically healthy obesity (MHO) continues. Many studies have investigated this relationship by examining MHO at baseline with longitudinal follow-up, with inconsistent results. OBJECTIVES: The authors hypothesized that MHO at baseline is transient and that transition to metabolic syndrome (MetS) and duration of MetS explains heterogeneity in incident cardiovascular disease (CVD) and all-cause mortality. METHODS: Among 6,809 participants of the MESA (Multi-Ethnic Study of Atherosclerosis) the authors used Cox proportional hazards and logistic regression models to investigate the joint association of obesity (≥30 kg/m2) and MetS (International Diabetes Federation consensus definition) with CVD and mortality across a median of 12.2 years. We tested for interaction and conducted sensitivity analyses for a number of conditions. RESULTS: Compared with metabolically healthy normal weight, baseline MHO was not significantly associated with incident CVD; however, almost one-half of those participants developed MetS during follow-up (unstable MHO). Those who had unstable MHO had increased odds of CVD (odds ratio [OR]: 1.60; 95% confidence interval [CI]: 1.14 to 2.25), compared with those with stable MHO or healthy normal weight. Dose response for duration of MetS was significantly and linearly associated with CVD (1 visit with MetS OR: 1.62; 95% CI: 1.27 to 2.07; 2 visits, OR: 1.92; 95% CI: 1.48 to 2.49; 3+ visits, OR: 2.33; 95% CI: 1.89 to 2.87; p value for trend <0.001) and MetS mediated approximately 62% (44% to 100%) of the relationship between obesity at any point during follow-up and CVD. CONCLUSIONS: Metabolically healthy obesity is not a stable or reliable indicator of future risk for CVD. Weight loss and lifestyle management for CVD risk factors should be recommended to all individuals with obesity.

The obesity paradox: An analysis of pre-procedure weight trajectory on survival outcomes in patients undergoing transcatheter aortic valve implantation.

INTRODUCTION: Increased mortality has been observed in those with cardiovascular diseases who are of normal body mass index (BMI) compared to the overweight and the obese. A similar association has been demonstrated in patients undergoing transcatheter aortic valve (TAVI) implantation. However, it still remains unclear whether low or normal BMI itself is unfavourable or whether this is merely a reflection of cardiac cachexia due to severe aortic stenosis. The hypothesis for the study was that weight change prior to TAVI may be associated with increased mortality following the procedure. SUBJECTS, MATERIALS AND METHODS: Single centre retrospective analysis using the SWEDEHEART registry, national mortality statistics and local hospital database. Body mass index was used as the anthropomorphic measurement and patients grouped by WHO categories and weight change trajectory before and at TAVI. Kaplan-Meier survival was constructed and a Cox proportional hazard model used to evaluate predictors of outcome. RESULTS: Consecutive data on 493 patients with three year follow-up between 2008-2015 were evaluated. Overweight and obese body mass index categories (BMI>25) were associated with improved mortality compared to normal and underweight patients (BMI<25) (log rank p=0.02), hazard ratio of 0.68 (0.50-0.93). Weight loss trajectory was associated with increased mortality compared to stable weight (log rank p=0.01), hazard ratio 1.64 p=0.025. CONCLUSION: The pre-procedural weight trajectory of patients undergoing TAVI is an important predictor of clinical outcome after TAVI. Patients with stable weight trajectories are associated with improved mortality outcome compared to those with decreasing weight.

Improving risk estimates for metabolically healthy obesity and mortality using a refined healthy reference group.

OBJECTIVE: We aimed to re-examine mortality risk estimates for metabolically healthy obesity by using a 'stable' healthy non-obese referent group. DESIGN: Prospective cohort study. METHODS: Participants were 5427 men and women (aged 65.9 ± 9.4 years, 45.9% men) from the English Longitudinal Study of Ageing. Obesity was defined as body mass index ≥30 kg/m2 (vs non-obese as below this threshold). Based on blood pressure, HDL cholesterol, triglycerides, glycated hemoglobin and C-reactive protein, participants were classified as 'healthy' (0 or 1 metabolic abnormality) or 'unhealthy' (≥2 metabolic abnormalities). RESULTS: Totally, 671 deaths were observed over an average follow-up of 8 years. When defining the referent group based on 1 clinical assessment, the unhealthy non-obese (hazard ratio (HR) = 1.22; 95% CI: 1.01, 1.45) and unhealthy obese (HR = 1.29; CI: 1.05, 1.60) were at greater risk of all-cause mortality compared to the healthy non-obese, yet no excess risk was seen in the healthy obese (HR = 1.14; CI: 0.83, 1.52). When we re-defined the referent group based on 2 clinical assessments, effect estimates were accentuated and healthy obesity was at increased risk of mortality (HR = 2.67; CI: 1.64, 4.34). CONCLUSION: An unstable healthy referent group may make 'healthy obesity' appear less harmful by obscuring the benefits of remaining never obese without metabolic dysfunction.

Risk of all-cause mortality in abdominal obesity phenotypes: Tehran Lipid and Glucose Study.

BACKGROUND AND AIM: Long-term health risks in the so-called "healthy obesity" phenotypes remain controversial. Also it is unknown if "metabolically healthy abdominal obese" (MHAO) phenotype is at increased risk of all-cause mortality compared to their non-abdominally obese counterparts. In this study we assessed the risk of all-cause mortality in different abdominal obesity phenotypes. METHODS AND RESULTS: In this large population-based cohort, 8804 participants (aged ≥ 30 years), from the Tehran Lipid and Glucose Study (TLGS) were enrolled and followed for a median of 12.0 (8.7-12.5) years. Abdominal obesity was defined using national waist circumference (WC) cut-off points of ≥89 cm for men and ≥91 cm for women. Metabolic health was defined as ≤1 components of metabolic syndrome (excluding WC), using the Joint Interim Statement (JIS) definition. Baseline prevalence of MHAO phenotype was 12.8% in the whole population and 23.4% in those with abdominal obesity. A total of 540 all-cause death occurred during the follow-up. After multivariate adjustment, all-cause mortality risk in MHAO phenotype was not significantly increased compared to "metabolically healthy non abdominal obese" (MHNAO) as the reference group (HR: 1.35, CI: 0.89-2.03). CONCLUSION: Our results indicate that MHAO individuals were not at higher risk for all-cause mortality over a median of 12 years follow-up. However, considering inadequate power of our analysis for fully adjusted model, larger studies with more follow-ups are needed.

Mediterranean diet and mortality risk in metabolically healthy obese and metabolically unhealthy obese phenotypes.

BACKGROUND: The Mediterranean diet has been consistently associated with reduced mortality risk. Few prospective studies have examined whether the benefits from a Mediterranean diet are equally shared by obese individuals with varying metabolic health. OBJECTIVE: The objective of this study was to investigate the association between Mediterranean diet, metabolic phenotypes and mortality risk in a representative obese US population. METHODS: Data from 1739 adults aged 20-88 years were analyzed from participants of the National Health and Nutrition Examination Survey III, 1988-1994 followed up for deaths until 31 December 2011 in a prospective cohort analysis. Mediterranean Diet Scores (MDS) were created to assess the adherence to Mediterranean diet. Participants were classified as metabolically healthy obese (MHO) phenotype (0 or 1 metabolic abnormality) or metabolically unhealthy obese (MUO) phenotype (two or more metabolic abnormalities), based on high glucose, insulin resistance, blood pressure, triglycerides, C-reactive protein and low high-density lipoprotein cholesterol. RESULTS: The MHO phenotype (n=598) was observed in 34.8% (s.e., 1.7%) of those who were obese (mean body mass index was 33.4 and 34.8 in MHO and MUO phenotypes, respectively). During a median follow-up of 18.5 years, there were 77 (12.9%) and 309 (27.1%) deaths in MHO and MUO individuals, respectively. In MHO individuals, the multivariable-adjusted hazard ratio (HR) of all-cause mortality in the highest tertile compared with the first tertile of MDS was 0.44 (95% confidence interval (CI), 0.26-0.75; P for trend <0.001), after adjustment for potential confounders. A five-point (1 s.d.) increment in the adherence to MDS was associated with a 41% reduction in the risk of all-cause mortality (HR, 0.59; 95% CI, 0.37-0.94). Similar findings were obtained when we restricted our analyses to those with or without prevalent diabetes mellitus and hypertension. We did not observe mortality risk reduction in either individuals with MUO phenotype or all obese participants combined. CONCLUSIONS: Adherence to a Mediterranean dietary pattern appears to reduce mortality in the MHO phenotype, but not among the MUO phenotype in an obese population.

The long-term prognosis of cardiovascular disease and all-cause mortality for metabolically healthy obesity: a systematic review and meta-analysis.

BACKGROUND: Metabolically healthy obese phenotype (MHO) refers to obese individuals with absence of metabolic abnormalities such as dyslipidaemia, insulin resistance and hypertension. Many studies reported the long-term prognosis of MHO on diseases and mortality with inconsistent results. METHODS: We performed a meta-analysis to assess the risks of cardiovascular (CV) events and all-cause mortality for MHO individuals. Original prospective observational studies were searched in Medline, EMBASE, Web of Science and Cochrane library up to 30 September 2015. In this meta-analysis, the relative risk (RR) calculated on the basis of the incident number of disease events and deaths in participants and the corresponding multivariable-adjusted HR were both extracted to calculate pooled risk estimates. A random-effects model was used if there was heterogeneity among studies; otherwise, the fixed-effects model was used. RESULTS: 22 prospective studies, involving 584 799 participants, were archived in the analyses. With metabolically healthy normal weight as the reference, the MHO phenotype was associated with a higher risk of CV events (RR 1.50, 95% CI 1.27 to 1.77; HR 1.60, 95% CI 1.38 to 1.84). However, MHO individuals were not associated with increased risk of all-cause mortality (RR 1.18, 95% CI 0.83 to 1.66; HR 1.07, 95% CI 0.92 to 1.25). CONCLUSIONS: The meta-analysis confirms a positive association between a metabolically healthy obese phenotype and the risk of CV events. However, higher risk for all-cause mortality is not evident in metabolically healthy obese individuals.

Cardiometabolic disease risk in metabolically healthy and unhealthy obesity: Stability of metabolic health status in adults.

OBJECTIVE: To assess the stability of metabolic status and body mass index (BMI) status and their relative contribution to risk of diabetes, cardiovascular events, and mortality. METHODS: A total of 14,685 participants from the Atherosclerosis Risk in Communities Study and 4,990 from the Coronary Artery Risk Development in Young Adults Study were included. People with healthy obesity (HO) are defined as those meeting all three indices of blood pressure, blood glucose, and blood lipids. People with unhealthy obesity crossed the risk threshold for all three criteria. RESULTS: In both healthy and unhealthy subgroups, risks for coronary heart disease (CHD), stroke, and mortality were comparable among BMI status during a mean 18.7-year follow-up. When compared with HO, hazard ratios were increased for diabetes (5.56, 95% confidence interval [CI] 4.12-7.48), CHD (5.60, 95% CI 3.14-9.98), stroke (4.84, 95% CI 2.13-10.97), and mortality (2.6, 95% CI 1.88-3.61) in people with unhealthy obesity. BMI only moderately increased the risks for diabetes among healthy subjects. In the Coronary Artery Risk Development in Young Adults Study over 20 years, 17.5% of lean subjects and 67.3% of overweight subjects at baseline developed obesity during follow-up. Despite rising BMI, metabolic status remained relatively stable. CONCLUSIONS: Metabolic status is relatively stable despite rising BMI. HO had lower risks for diabetes, CHD, stroke, and mortality than unhealthy subjects but increased diabetes risks than healthy lean people. Cardiometabolic risk factors confer much higher risk than obesity per se.

Metabolically healthy obesity and the risk of cardiovascular disease and type 2 diabetes: the Whitehall II cohort study.

AIM: The metabolically healthy obese (MHO) phenotype refers to obese individuals with a favourable metabolic profile. Its prognostic value is unclear and may depend on the health outcome being examined. We examined the association of MHO phenotype with incident cardiovascular disease (CVD) and type 2 diabetes. METHODS AND RESULTS: Body mass index and metabolic health, assessed using the Adult Treatment Panel-III (ATP-III) criteria, were assessed on 7122 participants (69.7% men) from the Whitehall II study, aged 39-63 years in 1991-93. Incident CVD (coronary heart disease or stroke) and type 2 diabetes were ascertained from medical screenings (every 5 years), hospital data, and registry linkage until 2009. A total of 657 individuals (9.2% of the cohort) were obese and 42.5% of these were classified as MHO in 1991-93. Over the median follow-up of 17.4 years, there were 828 incident cases of CVD and 798 incident cases of type 2 diabetes. Compared with metabolically healthy normal weight individuals, MHO subjects were at increased risk for CVD (HR = 1.97, 95% CI: 1.38-2.80) and type 2 diabetes (3.25, 95% CI: 2.32-4.54). There was excess risk in metabolically unhealthy obese compared with MHO for type 2 diabetes (1.98, 95% CI: 1.39-2.83) but not CVD (1.23, 95% CI: 0.81-1.87). Treating all measures as time varying covariates produced similar findings. CONCLUSION: For type 2 diabetes, the MHO phenotype is associated with lower risk than the metabolically unhealthy obese, but for CVD the risk is as elevated in both obesity phenotypes.