Effect of metabolically healthy obesity on the development of arterial stiffness: a prospective cohort study

Background

Metabolically healthy obesity (MHO) has been reported to be associated with the development of vascular damage by the carotid intima-media thickness, but the relationship between metabolic health and obesity phenotypes and arterial stiffness is still unknown. Our hypothesized that different metabolic health and obesity phenotypes might be associated with the development of arterial stiffness, and that subjects in MHO phenotype might not have increased risks of arterial stiffness compared with those in metabolically healthy nonobesity phenotype (MHNO), while metabolic unhealthy individuals might have increased risks of arterial stiffness.

Methods

A prospective cohort of 2076 participants (aged 36-48 years) who were enrolled in the Hanzhong Adolescent Hypertension Cohort Study in 2017 was analyzed in a cross-sectional analysis. A subgroup of 202 participants from 2005 to 2017 was selected by an isometric sampling method and was included in the final longitudinal analysis.

Results

We identified four metabolic health and obesity phenotypes for both the cross-sectional and longitudinal analyses as follows: MHNO, metabolically unhealthy nonobesity (MUNO), MHO, and metabolically unhealthy obesity (MUO). In the cross-sectional analysis, individuals with the MHO phenotype had the lowest brachial-ankle pulse wave velocity (baPWV) levels of the four phenotypes (P < 0.001), and participants with the MHO phenotype had a similar risk of arterial stiffness after fully adjustment [odds ratio (OR) = 0.99 (0.61-1.60)] as the MUNO subjects. Subjects with metabolically unhealthy status had a significantly higher risk of arterial stiffness than the MHNO individuals, particularly females (P < 0.005). In the longitudinal analysis, subjects with the MUNO and MUO phenotypes had a significantly higher risk of arterial stiffness than the MHNO individuals after adjustment for age and sex [OR = 5.21 (2.26-12.02), OR = 3.32 (1.18-9.32), respectively].

Conclusions

The MHO phenotype did not significantly increase the progression of arterial stiffness. Metabolically unhealthy individuals (MUNO, MUO), regardless of obesity status, showed a worse effect for the development of arterial stiffness, particularly females.

Trial registration

NCT02734472. Registered 12 April 2016 - Retrospectively registered, http:www.clinicaltrials.gov.

Metabolically Healthy Obesity: Criteria, Epidemiology, Controversies, and Consequences

PURPOSE OF REVIEW

To present a comprehensive overview regarding criteria, epidemiology, and controversies that have arisen in the literature about the existence and the natural course of the metabolic healthy phenotype.

RECENT FINDINGS

The concept of metabolically healthy obesity (MHO) implies that a subgroup of obese individuals may be free of the cardio-metabolic risk factors that commonly accompany obese subjects with adipose tissue dysfunction and insulin resistance, known as having metabolic syndrome or the metabolically unhealthy obesity (MUO) phenotype. Individuals with MHO appear to have a better adipose tissue function, and are more insulin sensitive, emphasizing the central role of adipose tissue function in metabolic health. The reported prevalence of MHO varies widely, and this is likely due the lack of universally accepted criteria for the definition of metabolic health and obesity. Also, the natural course and the prognostic value of MHO is hotly debated but it appears that it likely evolves towards MUO, carrying an increased risk for cardiovascular disease and mortality over time. Understanding the pathophysiology and the determinants of metabolic health in obesity will allow a better definition of the MHO phenotype. Furthermore, stratification of obese subjects, based on metabolic health status, will be useful to identify high-risk individuals or subgroups and to optimize prevention and treatment strategies to compact cardio-metabolic diseases.

Metabolically Healthy Obesity and Bariatric Surgery

A peculiar category of persons with obesity lacking common metabolic disturbances has been depicted and termed as metabolically healthy obesity (MHO). Yet, although MHO patients are free of obesity-associated complications, they might not be entirely precluded from developing cardio-metabolic disorders. Among patients with morbid obesity (MO) who are referred to bariatric surgery, a subset of metabolically healthy MO (MHMO) has been identified and the question arises if these patients would benefit from surgery in terms of mitigating the peril of cardio-metabolic complications. We revisited the pathophysiological mechanisms that define MHO, the currently available data on the cardio-metabolic risk of these patients and finally we reviewed the benefits of bariatric surgery and the urge to better characterize MHMO before submission to surgery.

A comprehensive metabolic profiling of the metabolically healthy obesity phenotype

BACKGROUND

The ever-increasing prevalence of obesity constitutes a major health problem worldwide. A subgroup of obese individuals has been described as "metabolically healthy obese" (MHO). In contrast to metabolically unhealthy obese (MUO), the MHO phenotype has a favorable risk profile. Despite this, the MHO phenotype is still sub-optimally characterized with respect to a comprehensive risk assessment. Our aim was to increase the understanding of metabolic alterations associated with healthy and unhealthy obesity.

METHODS

In this cross-sectional study, men and women (18-70 years) with obesity (body mass index (BMI) ≥ 30 kg/m²) or normal weight (NW) (BMI ≤ 25 kg/m²) were classified with MHO (n = 9), MUO (n = 10) or NW (n = 11) according to weight, lipid profile and glycemic regulation. We characterized individuals by comprehensive metabolic profiling using a commercial available high-throughput proton NMR metabolomics platform. Plasma fatty acid profile, including short chain fatty acids, was measured using gas chromatography.

RESULTS

The concentrations of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) subclasses were overall significantly higher, and high density lipoprotein (HDL) subclasses lower in MUO compared with MHO. VLDL and IDL subclasses were significantly lower and HDL subclasses were higher in NW compared with MHO. The concentration of isoleucine, leucine and valine was significantly higher in MUO compared with MHO, and the concentration phenylalanine was lower in NW subjects compared with MHO. The fatty acid profile in MHO was overall more favorable compared with MUO.

CONCLUSIONS

Comprehensive metabolic profiling supports that MHO subjects have intermediate-stage cardiovascular disease risk marker profile compared with NW and MUO subjects.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01034436, Fatty acid quality and overweight (FO-study).

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.

Impact of metabolically healthy obesity on the risk of incident gastric cancer: a population-based cohort study

BACKGROUND

The risk of colon or breast cancer in metabolically healthy obese (MHO) were lower than that in metabolically abnormal obese (MAO). We hypothesized that the risk of incident gastric cancer in MHO is lower than that in MAO.

METHODS

This historical cohort study included 19,685 Japanese individuals who received health-checkup programs from 2003 to 2016. Each subject was classified as metabolically healthy (MH) (no metabolic abnormalities) or metabolically abnormal (MA) (one or more metabolic abnormalities), according to four metabolic factors (hypertension, impaired fasting glucose, hypertriglyceridemia and low HDL-cholesterol). Obese (O) or non-obese (NO) was classified by a BMI cutoff of 25.0 kg/m². Hazard ratios of metabolic phenotypes for incident gastric cancer were calculated by the Cox proportional hazard model with adjustments for age, sex, alcohol consumption, smoking and exercise.

RESULTS

Over the median follow-up period of 5.5 (2.9-9.4) years, incident rate of gastric cancer was 0.65 per 1000 persons-years. Incident rate of MHNO, MHO, MANO and MAO were 0.33, 0.25, 0.80 and 1.21 per 1000 persons-years, respectively. Compared with MHNO, the adjusted hazard ratios for development of gastric cancer were 0.69 (95% CI 0.04-3.39, p = 0.723) in MHO, 1.16 (95% CI 0.63-2.12, p = 0.636) in MANO and 2.09 (95% CI 1.10-3.97, p = 0.024) in MAO.

CONCLUSIONS

This study shows that individuals with MAO, but not those with MHO, had an elevated risk for incident gastric cancer. Thus, we should focus more on the presence of metabolic abnormalities rather than obesity itself for incident gastric cancer.

Metabolically Healthy Obesity and Risk of Incident Chronic Kidney Disease in a Korean Cohort Study

BACKGROUND

The incident of chronic kidney disease (CKD) of metabolically healthy obesity (MHO) has not been consistently determined.

METHODS

This study used data of Anseong Ansan community-based cohort, a part of the Korean Genome and Epidemiology Study (KoGES) provided by the Korea Center for Disease Control and Prevention (KCDC). Surveys were received from the Anseung and Ansan residents every two years between 2001-2002 and 2015-2016 for a total of 7 surveys over all. The subjects were divided into 4 phenotypes based on the presenting obesity and metabolic syndrome; 1) metabolically healthy normal weight (MHNW), 2) metabolically healthy obesity (MHO), 3) metabolically abnormal normal weight (MANW), and 4) metabolically abnormal obesity (MAO). Data were analyzed using the Cox proportional hazards regression model.

RESULTS

Of 8,865 subjects, 1,551 cases of 49,995 person-year (3.1%) developed incident CKD. At an adjusted hazard ratio (HR) of 1.13, the MHO group was not associated with a higher risk of incident CKD (95% confidence interval (CI): 0.92-1.41, P =0.234, using MHNW as the reference). The adjusted HRs of the MANW and MAO groups for incident CKD were significantly higher than those of the MHNW groups: 1.31 (95% CI: 1.05-1.64, P=0.017) for MANW and 1.49 (95% CI: 1.23-1.79, P<0.001) for MAO.

CONCLUSION

MHO is not associated with a high risk of CKD, and that MANW and MAO increase the risk of the incident CKD. Thus, it is important to consider metabolic health status rather than obesity when evaluating CKD risk.

Fasting insulin resistance affects the prevalence of metabolically healthy obesity in Brazilian adolescents

AIM

We aimed to assess the influence of fasting insulin resistance on metabolically healthy obesity (MHO) prevalence in adolescents and to identify associated factors.

METHODS

This retrospective, registry-based, cross-sectional study included 418 (51.9% girls) 10- to 18-year-old adolescents with obesity from a tertiary outpatient clinic in Sao Paulo, Brazil, between 2009 and 2013. The prevalence of MHO was estimated according to two definitions: (i) no cardiometabolic risk factors (CMRF) by the International Diabetes Federation parameters and (ii) no CMRF and homeostatic model assessment for insulin resistance <3.16. Adjusted prevalence ratios and 95% confidence intervals (CI) evaluated the association of gender, age, pubertal stages, skin colour and degree of obesity with MHO.

RESULTS

Metabolically healthy obesity prevalence was lower in definition II than definition I (12.7%; 95% CI 9.1-16.3% versus 43.1%; 95% CI 38.0-48.2%, respectively). Adjusted results showed negative association between severe obesity and MHO by both definitions (p ≤ 0.01). Male and later pubertal stages were also less likely to have MHO, but neither remained significant in definition II.

CONCLUSION

Metabolically healthy obesity prevalence decreased when insulin resistance was part of the definition. Detecting pre-clinical insulin resistance may improve the management of treatment-seeking adolescents, especially when they present no CMRF.

Effect of Metabolically Healthy Obesity on the Development of Carotid Plaque in the General Population: A Community-Based Cohort Study

Aim: Obesity and metabolic syndrome (MetS) frequently coexist and are both important risk factors for cardiovascular disease. However, the pathophysiological role of obesity without MetS, also referred to as metabolically healthy obesity (MHO), remains unclear. In this study, we aim to clarify the effect of MHO on the development of carotid plaque using a community-based cohort.

Methods: We examined 1,241 subjects who underwent health checkups at our institute. Obesity was defined as body mass index of ≥ 25.0 kg/m². Subjects were divided into three groups: non-obese, MHO, and metabolically unhealthy obesity (MUO).

Results: The prevalence of carotid plaque, defined as intima-media thickness (IMT) ≥ 1.1 mm, was higher in subjects with MUO and MHO than in non-obese subjects. Multivariable analysis demonstrated that MHO (odds ratio 1.6, p = 0.012) and MUO (odds ratio 1.9, p = 0.003) as well as age of ≥ 65 years, male sex, hypertension, and diabetes mellitus were independently associated with carotid plaque formation. A similar trend was observed in each subgroup according to age and sex.

Conclusions: MHO increased the prevalence of carotid plaque when compared with non-obese subjects, suggesting the potential significance of MHO in the development of subsequent cardiovascular diseases.

Obesity and Risk of Peptic Ulcer Disease: A Large-Scale Health Check-Up Cohort Study

The association between obesity and peptic ulcer disease (PUD) is inconclusive. To evaluate the association of obesity and metabolically healthy obesity (MHO) with PUD risk, we performed a retrospective cohort study of 32,472 subjects without PUD at baseline who underwent repeated health examinations. Participants were stratified by body mass index (BMI) and metabolically healthy state. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard modelling. During the follow-up period, 1940 PUD cases occurred. PUD, particularly gastric ulcer (GU), had significantly higher cumulative incidence in obese subjects compared to non-obese subjects (p value < 0.001). The HR for developing GU was 1.32 (95% CI, 1.16-1.49; p value <0.001); after adjusting for confounding factors (lifestyle, metabolic, and Helicobacter pylori status), the association was no more significant (p value = 0.789). For duodenal ulcer (DU), cumulative incidence between obese and non-obese groups was not significantly different (p value = 0.464). The risk of developing DU in the obese group was not significantly different from the non-obese group (HR 0.95; 95% CI, 0.83-1.09; p value = 0.469) and consistently showed no association after adjusting for metabolic parameters (p value = 0.199). Furthermore, MHO subjects had no increase in GU or DU risks. In this large cohort study, PUD risk was not associated with obesity or MHO.

Associations of metabolically healthy obesity with prevalence and progression of coronary artery calcification: Results from the Heinz Nixdorf Recall Cohort Study

BACKGROUND AND AIMS

There is controversy on the potentially benign nature of metabolically healthy obesity (MHO), i.e., obese persons with few or no metabolic abnormalities. So far, associations between MHO and coronary artery calcification (CAC), a measure of subclinical atherosclerosis, have mainly been studied cross-sectionally in Asian populations. We assessed cross-sectional and longitudinal MHO CAC associations in a Caucasian population.

METHODS AND RESULTS

In the Heinz Nixdorf Recall Study, a population-based cohort study in Germany, CAC was assessed by electron-beam tomography at baseline and at 5-year follow-up. For cross-sectional and longitudinal analyses, we included 1585 participants free of coronary heart disease at baseline, with CAC measurements at baseline and at follow-up, and with either normal weight (BMI 18.5-24.9 kg/m²) or obesity (BMI ≥30.0 kg/m²) at baseline. We used four definitions of MHO. In our main analysis, we defined obese persons as metabolically healthy if they met ≤1 of the NCEP ATP III criteria for the definition of the metabolic syndrome - waist circumference was not taken into account because of collinearity with BMI. Persons with MHO had a higher prevalence of CAC than metabolically healthy normal weight (MHNW) persons (prevalence ratio = 1.59 (95% confidence interval 1.38-1.84) for the main analysis). Persons with MHO had slightly larger odds of CAC progression than persons with MHNW (odds ratios ranged from 1.17 (0.69-1.99) to 1.48 (1.02-2.13) depending on MHO definition and statistical approach).

CONCLUSION

Our analyses on MHO CAC associations add to the evidence that MHO is not a purely benign health condition.

Body Composition and Cardiorespiratory Fitness Between Metabolically Healthy Versus Metabolically Unhealthy Obese Black and White Adolescents

PURPOSE

We compared body composition and cardiorespiratory fitness (CRF) between metabolically healthy overweight/obese (MHO) versus metabolically unhealthy overweight/obese (MUO) adolescents in 189 black and white adolescents (BMI ≥ 85th percentile, 12-18 years of age).

METHODS

Participants were defined as MHO or MUO if their insulin-stimulated glucose disposal, measured by a 3-hour hyperinsulinemic-euglycemic clamp, was in the upper quartile or in the lower three quartiles. Total fat was measured by dual-energy X-ray absorptiometry, and visceral adiposity and liver fat were measured by magnetic resonance imaging and proton magnetic resonance spectroscopy, respectively. CRF was measured by a graded maximal treadmill test.

RESULTS

Black MHO adolescents had lower (p < .05) 2-hour oral glucose tolerance test glucose, triglycerides, very-low-density lipoprotein cholesterol, and higher high-density lipoprotein cholesterol, with a lower prevalence of impaired fasting glucose and impaired glucose tolerance compared with black MUO adolescents. White MHO adolescents had lower (p < .05) triglycerides and very-low-density lipoprotein cholesterol, with a lower prevalence of impaired fasting glucose compared with white MUO adolescents. Independent of race, CRF was higher in MHO versus MUO adolescents. After accounting for gender, Tanner stage, and BMI, there were no differences in total fat (kg, %) between MHO versus MUO in both races. MHO adolescents had significantly lower trunk fat, waist circumference, and visceral fat compared with MUO adolescents in both races. In whites, MHO adolescents had lower (p = .055) liver fat compared with MUO adolescents.

CONCLUSIONS

Independent of race, the MHO phenotype is characterized by high CRF, lower waist circumference and visceral fat, and lower rates of dysglycemia in youth.

Serum Uric Acid Levels as an Indicator for Metabolically Unhealthy Obesity in Children and Adolescents

BACKGROUND

Metabolically healthy obesity (MHO) refers to those individuals who do not show cardiometabolic abnormalities. Our aim was to identify potential clinical and metabolic indicators that may help to distinguish between metabolically healthy and unhealthy individuals amongst overweight and obese children and adolescents.

METHODS

The study involved 246 overweight/obese and 212 normal-weight individuals enrolled in the LIFE Child study, aged between 6 and 18 years. Overweight/obese individuals without cardiovascular risk factors (fasting serum lipids, blood pressure, and glucose) were classified as MHO. Individuals meeting 1 or more criteria of cardiovascular risk factors were classified as metabolically unhealthy obesity (MUO).

RESULTS

Among the 246 overweight/obese individuals, 173 (70%) were MHO and 73 (30%) were MUO. The MHO individuals were younger, more likely to be male, and had lower BMI SDS. In the logistic regression models, uric acid (UA) SDS (OR 1.61, 95% CI 1.1-2.6, p = 0.004), waist circumference SDS (OR 2.50, 95% CI 1.2-6.4, p = 0.017), and C-peptide (OR 4.05, 95% CI 3.5-91, p = 0.003) were significant indicators of MUO.

CONCLUSION

Our results suggest that nearly one-third of overweight/obese children are already identified as MUO. Serum levels of UA can be used as an indicator of unhealthy obesity in youth, where lower levels of UA indicate a lower risk and higher levels suggest a higher risk of MUO. We note that the relevance of identifying potential indicators remains the first most important step in future clinical research.

Predictors of the transition from metabolically healthy obesity to unhealthy obesity

PURPOSE

Evidence that metabolically healthy obesity (MHO) is a stable benign condition is unclear. The aim of this study was to estimate the transition of MHO subjects to unhealthy obesity (occurrence of cardio-metabolic events and/or risk factors) and its predictors.

METHODS

We conducted an explorative follow-up study in a subset of MHO patients > 40 years without any cardio-metabolic risk factors and with normal LDL cholesterol (LDLc) levels, identified among 1530 obese patients. Due to the low sample size, a bootstrap approach was applied to identify the variables to be included in the final multivariate discrete-time logit model.

RESULTS

The prevalence of MHO was 3.7%. During the follow-up (mean 6.1 years, SD 2.0), none of the MHO reported cardiovascular events, diabetes or prediabetes; 26 subjects developed risk factors (53% high LDLc and 50% hypertension). At the 6 and 12-year of follow-up, the cumulative incidence of transition to unhealthy obesity was 44% (95% CI 31-59%) and 62% (95% CI 45-79%), the incidence of high LDLc was 23% (95% CI 13-37%) and 40% (95% CI 25-59%) and that of hypertension was 20% (95% CI 11-33%) and 30% (95% CI 17-48%). LDLc and duration of follow-up were independent predictors of the transition from MHO to unhealthy obesity [OR 1.038 (1.005-1.072) and 1.360 (1.115-1.659)].

CONCLUSIONS

Results suggest that (a) MHO individuals do not move over time forward diabetes/prediabetes but develop risk factors, such as hypertension and higher LDL c that worsen the cardiovascular prognosis; (b) LDLc and the flow of time independently predict the transition to unhealthy status.

LEVEL OF EVIDENCE

Level III, cohort study.

Association of obesity phenotypes with electrocardiographic left ventricular hypertrophy in the general population

OBJECTIVE

Increasing evidence doubts the benign nature of metabolically healthy obesity (MHO). An investigation of the association of MHO and other obesity phenotypes with electrocardiographic left ventricular hypertrophy (ECG-LVH), a risk factor for cardiovascular disease (CVD), can give insight into the pathophysiological basis for increased risk of CVD linked to these phenotypes.

METHODS

This analysis included 3997 participants (58.7 ± 13.6 years; 51.8% women) without CVD from the NHANES-III. Metabolic syndrome was defined according to the Adult Treatment Panel III. Obesity was defined as body mass index ≥30 kg/m2. Multivariable logistic regression was used to examine the cross-sectional association between 4 obesity phenotypes (metabolically healthy non-obese (MHNO) (reference), metabolically unhealthy non-obese (MUNO), MHO and metabolically unhealthy obese (MUO) with Cornell voltage ECG-LVH.

RESULTS

There was an incremental increase in the prevalence of ECG-LVH across obesity phenotypes with the highest prevalence in the MUO followed by MHO, MUNO and then MHNO (ECG-LVH = 6.45%, 5%, 4.71%, and 1.69%, respectively, trend p-value < 0.001). Also, there was incremental increase in the strength of associations with ECG-LVH across obesity phenotypes with higher odds of ECG-LVH in the MUO (OR (95% CI): 4.12 (2.30-7.39) followed by MUNO (OR (95% CI): 2.62 (1.45-4.73) then MHO (OR (95% CI): 2.45 (1.11-5.43) compared to MHNO. The MHO association with ECG-LVH was stronger in men than women (OR (95% CI): 5.55 (1.49-20.70) vs. 1.94 (0.71-5.24) respectively; interaction p-value = 0.04).

CONCLUSIONS

Obesity phenotypes including MHO are associated with ECG-LVH, thus further questioning the concept of benign obesity.

Distribution of metabolic/obese phenotypes and association with diabetes: 5 years' cohort based on 22,276 elderly

AIMS

To describe the distribution and changes of different metabolic/obese phenotypes among more than 22,000 male elderly in China, and also explore the association with diabetes incidence.

METHODS

A cohort study based on 22,276 male elderly was conducted in Beijing, from 2009 to 2013. Multiple Cox model was used to calculate the relative risk.

RESULTS

There were only 53.8% of total participants who kept the same phenotype for the 5 years. On the whole, participants with metabolically unhealthy phenotypes had higher relative risks (RRs) than those with metabolically healthy phenotypes. RRs for diabetes showed an increasing trend along with metabolic abnormalities (p < 0.001). However, no statistically significant difference was found across different obese status with the same number of metabolic abnormalities. Changes of metabolic/obese status also showed the same trend. Those who had kept metabolic unhealthy had the highest RRs for diabetes incidence, which was higher than those who kept obesity.

CONCLUSIONS

Both metabolically healthy obesity and metabolically unhealthy normal weight phenotypes had an increased risk for diabetes incidence, and metabolic abnormalities might have more influence on diabetes than obesity itself. Changes of metabolic/obese status also had an important impact on diabetes incidence.

Prevalence and predictors of metabolically healthy obesity in adolescents: findings from the national "Jeeluna" study in Saudi-Arabia

BACKGROUND

Obese children and adolescents may vary with respect to their health profile, an observation that has been highlighted by the characterization of metabolically healthy obesity (MHO). The objectives of this study were to examine the prevalence of MHO amongst obese adolescents in Saudi-Arabia, and investigate the anthropometric, socio-demographic, and lifestyle predictors of MHO in this age group.

METHODS

A national cross-sectional school-based survey (Jeeluna) was conducted in Saudi-Arabia in 2011-2012 (n = 1047 obese adolescents). Anthropometric, blood pressure and biochemical measurements were obtained. A multicomponent questionnaire covering socio-demographic, lifestyle, dietary, psychosocial and physical activity characteristics was administered. Classification of MHO was based on two different definitions. According to the first definition, subjects were categorized as MHO based on the absence of the following traditional cardiometabolic risk (CR) factors: systolic blood pressure (SBP) or diastolic blood pressure (DBP) >90th percentile for age, sex, and height; triglycerides (TG) > 1.25 mmol/L; high density lipoprotein-cholesterol (HDL-C) ≤1.02 mmol/L; glucose ≥5.6 mmol/L. The second definition of MHO was based on absence of any cardiometabolic risk factor, according to the International Diabetes Federation (IDF) criteria.

RESULTS

The prevalence of MHO ranged between 20.9% (IDF) and 23.8% (CR). Subjects with MHO were younger, less obese, had smaller waist circumference (WC) and were more likely to be females. Based on stepwise logistic regression analyses, and according to the IDF definition, body mass index (BMI) (OR = 0.89, 95% CI: 0.84-0.93) and WC (OR = 0.97, 95% CI: 0.96-0.98) were the only significant independent predictors of MHO. Based on the CR definition, the independent predictors of MHO included female gender (OR = 1.76, 95% CI: 1.29-2.41), BMI (OR = 0.97, 95% CI: 0.94-1.00), and weekly frequency of day napping (OR = 1.06, 95% CI: 1.00-1.12). Analysis by gender showed that vegetables' intake and sleep indicators were associated with MHO in boys but not in girls.

CONCLUSION

The study showed that one out of five obese adolescents is metabolically healthy. It also identified anthropometric factors as predictors of MHO and suggested gender-based differences in the association between diet, sleep and MHO in adolescents. Findings may be used in the development of intervention strategies aimed at improving metabolic heath in obese adolescents.

Role of Physical Activity and Fitness in the Characterization and Prognosis of the Metabolically Healthy Obesity Phenotype: A Systematic Review and Meta-analysis

The aims of the present article are to systematically review and meta-analyze the existing evidence on: 1) differences in physical activity (PA), sedentary behavior (SB), cardiorespiratory fitness (CRF) and muscular strength (MST) between metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO); and 2) the prognosis of all-cause mortality and cardiovascular disease (CVD) mortality/morbidity in MHO individuals, compared with the best scenario possible, i.e., metabolically healthy normal-weight (MHNW), after adjusting for PA, SB, CRF or MST. Our systematic review identified 67 cross-sectional studies to address aim 1, and 11 longitudinal studies to address aim 2. The major findings and conclusions from the current meta-analysis are: 1) MHO individuals are more active, spend less time in SB, and have a higher level of CRF (yet no differences in MST) than MUO individuals, suggesting that their healthier metabolic profile could be at least partially due to these healthier lifestyle factors and attributes. 2) The meta-analysis of cohort studies which accounted for PA (N = 10 unique cohorts, 100% scored as high-quality) support the notion that MHO individuals have a 24-33% higher risk of all-cause mortality and CVD mortality/morbidity compared to MHNW individuals. This risk was borderline significant/non-significant, independent of the length of the follow-up and lower than that reported in previous meta-analyses in this topic including all type of studies, which could be indicating a modest reduction in the risk estimates as a consequence of accounting for PA. 3) Only one study has examined the role of CRF in the prognosis of MHO individuals. This study suggests that the differences in the risk of all-cause mortality and CVD mortality/morbidity between MHO and MHNW are largely explained by differences in CRF between these two phenotypes.

Life course factors associated with metabolically healthy obesity: a protocol for the systematic review of longitudinal studies

BACKGROUND

There is heterogeneity among obese individuals, as some appear to have healthier metabolic profiles and decreased health risks. These individuals are defined as metabolically healthy obese (MHO), whilst those with unhealthy metabolic profiles are defined as metabolically unhealthy obese (MUO). To date, most research on MHO has been cross-sectional or focused on disease prognosis. However, longitudinal studies are required to provide greater insight into the life course factors that contribute to the development of MHO. This study aims to systematically review longitudinal studies investigating the association between life course exposures and future MHO status.

METHODS

Electronic databases (MEDLINE, SCOPUS, and Web of Science) will be searched using a trialled search strategy. Studies will be included following a double-screening process according to inclusion criteria to assess eligibility. Studies eligible for inclusion will include those that have a longitudinal observational design where a life course exposure occurred or was measured at least 1 year before the outcome, investigate a human study population, are published in English after 1956, and investigate the association between ≥ 1 life course exposure and ≥ 1 outcome that reflects a measure of cardiometabolic resilience to obesity. Accepted life course exposures will include body size, body composition, pubertal development, smoking, diet, physical activity, sedentary behaviour, and psychosocial stress. The primary measure of cardiometabolic resilience to obesity will be MHO as an outcome (at follow-up). Studies investigating the development of cardiometabolic risk factors in an obese group without specifying MHO will also be accepted, such as the development of the metabolic syndrome (MetS) in an obese group. Key results of included studies will be tabulated, and a narrative synthesis will be conducted.

DISCUSSION

This will be the first systematic review to summarise the literature on the life course correlates of MHO. Importantly, it may highlight which modifiable lifestyle factors could be targeted to delay the onset of cardiometabolic complications among the obese.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017057992.

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.

Metabolically healthy/unhealthy components may modify bone mineral density in obese people

Link between obesity and bone health is controversial. It seems that maybe the difference in metabolic status leads to this difference. We studied relation between metabolically healthy/unhealthy components with bone mineral density. Results showed metabolically unhealthy obesity (MUHO) phenotypes have better bone status at hip site than metabolically healthy obesity (MHO). Also, component metabolic can effect on BMD in different sites.

PURPOSE/INTRODUCTION

This cross-sectional study aimed to compare total BMD and L-L4 BMD in MHO and MUHO base on Karelis criteria.

METHODS

We enrolled 272 Iranian obese women and men (BMI ≥ 30). According to Karelis criteria, the participants were grouped base to MHO and MUHO. The body composition and BMD were assessed for all cases. Serum HDL-C, LDL-C, total cholesterol, triglyceride (TG), fasting blood glucose, homeostatic model assessment-insulin resistance (HOMA-IR), and hypersensitive C-reactive protein (hs-CRP) levels were quantified by ELISA method.

RESULTS

Our results demonstrate MUHO phenotype have high total BMD more than MHO (P = 0.01, CI = 0.12 to 0.21). Also, the results of logistic regression analysis showed MUHO have strongly associated with total BMD (β = -0.42, CI = - 0.31 to - 0.04, P = 0.009), but did not affected L2-L4 BMD (β = - 0.09, CI = - 0.14 to 0.08, P = 0.578); this represents that there was discordance in MUHO subjects. Our evidence implicated that HOMA-IR, high level serum TG, hs-CRP, and low level serum HDL had mediatory effect on relationship between obesity and high BMD at the hip region in MUHO subjects (P < 0.05).

CONCLUSION

Present evidence indicates that, could be a novel link between difference in MUH phenotype and MH phenotype with bone status. Also, component metabolic can effect on BMD in different sites.

Impact of dietary intake, lifestyle and biochemical factors on metabolic health in obese adolescents

BACKGROUND AND AIMS

Obesity devoid of metabolic abnormalities is known as metabolically healthy obesity (MHO). The aim of the study was to examine determinants of MHO during adolescence.

METHODS AND RESULTS

From among 710 obese adolescents, 43 girls and 57 boys were classified as metabolically unhealthy (abdominal obesity and ≥2 risk components of metabolic syndrome). MHO (absence of any cardiometabolic risk factor) was found in 211 girls and 131 boys (regardless of waist circumference) and in 33 girls and 27 boys (without abdominal obesity). Laboratory and anthropometric parameters, dietary records and various lifestyle factors were compared between MHO vs. those unhealthy. The prevalence of MHO regardless of waist circumference was higher in girls than in boys (53.1 vs. 41.9%) but comparable when abdominal obesity was excluded (8.3 vs. 8.6%). Anthropometric variables, levels of gamma-glutamyl transferase, total and low-density lipoprotein cholesterol in both genders, hs-C-reactive protein in girls and alanine aminotransferase in boys differentiated the two metabolic phenotypes. Uric acid was related to metabolic health only in the analysis of MHO without abdominal obesity. Total hours of sleep, bedtime, time of the last daily meal, regular meal consumption and protein intake in boys and screen time, the score of disinhibition and diet composition in girls were found to impact cardiometabolic health.

CONCLUSIONS

In obese adolescents, metabolic health was related to anthropometric and biochemical parameters and only weak associations were found with most of the lifestyle factors studied. Uric acid concentration associated with metabolic health when abdominal obesity was excluded.

Physical health-related quality of life in relation to metabolic health and obesity among men and women in Germany

Background

This study examined sex-specific differences in physical health-related quality of life (HRQoL) across subgroups of metabolic health and obesity. We specifically asked whether (1) obesity is related to lower HRQoL independent of metabolic health status and potential confounders, and (2) whether associations are similar in men and women.

Methods

We used cross-sectional data from the German Health Interview and Examination Survey 2008–11. Physical HRQoL was measured using the Short Form-36 version 2 physical component summary (PCS) score. Based on harmonized ATPIII criteria for the definition of the metabolic health and a body mass index ≥ 30 kg/m² to define obesity, individuals were classified as metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO). Sex-specific analyses including multivariable linear regression analyses were based on PCS as the dependent variable, metabolic health and obesity category as the independent variable with three categories and MHNO as the reference, and age, education, lifestyle and comorbidities as confounders.

Results

This study included 6860 participants (3298 men, 3562 women). Compared to MHNO, all other metabolic health and obesity categories had significantly lower PCS in both sexes. As reflected by the beta coefficients [95% confidence interval] from bivariable linear regression models, a significant inverse association with PCS was strongest for MUO (men: −7.0 [−8.2; −5.8]; women: −9.0 [−10.2; −7.9]), intermediate for MUNO (men: −4.2 [−5.3; −3.1]; women: −5.6 [−6.8; −4.4]) and least pronounced for MHO (men: −2.2 [−3.6; −0.8]; women −3.9 [−5.4; −2.5]). Differences in relation to MHNO remained statistically significant for all groups after adjusting for confounders, but decreased in particular for MUNO (men:–1.3 [−2.3; −0.3]; women: −1.5 [−2.7; −0.3].

Conclusions

Obesity was significantly related to lower physical HRQoL, independent of metabolic health status. Potential confounders including age, educational status, health-related behaviors, and comorbidities explained parts of the inverse relationship. Associations were evident in both sexes and consistently more pronounced among women than men.

Electronic supplementary material

The online version of this article (doi:10.1186/s12955-017-0688-7) contains supplementary material, which is available to authorized users.

Predictors of incident obesity phenotype in nonobese healthy adults

BACKGROUND

Despite their different cardiovascular consequences, little is known about predictors of metabolically healthy (MHO) and metabolically unhealthy obesity (MUHO). This cohort study was designed to address this question in participants of the Tehran Lipid and Glucose Study.

MATERIALS AND METHODS

Employing the Joint Interim Statement (JIS) metabolic syndrome criteria to define MHO/MUHO phenotypes, nonobese, otherwise healthy individuals, aged > 20 years (n = 3489) were recruited and followed up for a median of 13·4 years.

RESULTS

At the follow-up, MHO incidence rate in obese individuals was 36·6%. Comparing MHO vs. MUHO, female gender [odds ratio (OR) = 3·28, 95% confidence interval (CI) 1·27, 8·46)], increased body mass index (BMI; OR = 1·32, 95% CI: 1·12, 1·60) and elevated high-density lipoprotein cholesterol (HDL-C) levels (OR = 1·04, 95% CI: 1·02, 1·07) were related to higher odds of incident MHO, while older age (OR = 0·95, 95% CI: 0·92, 0·98), increased waist circumference (WC; OR = 0·86, 95% CI: 0·81, 0·91), higher WC gain (OR = 0·91, 95% CI: 0·87, 0·95) and increased diastolic blood pressure (DBP; OR = 0·94, 95% CI: 0·91, 0·98) prevented progression towards MHO.

CONCLUSIONS

While baseline BMI and WC were detrimental for developing MHO vs. MUHO, gender was the strongest predictor of incident obesity phenotype in healthy nonobese individuals.

Atrial fibrillation risk in metabolically healthy obesity: A nationwide population-based study

BACKGROUND

Metabolically healthy obese (MHO) individuals are reported to have a marginal increase in cardiovascular risk; however, their atrial fibrillation (AF) risk is unclear. We aimed to assess AF risk in MHO individuals and identify whether AF development is associated with obesity or influenced by metabolic comorbidities.

METHODS

A retrospective cohort of 389,321 individuals (age, 45.6±14.5years; male, 52.1%) was extracted from the Korean National Health Insurance sample database between 2004 and 2006 and followed-up for new-onset AF until 2013. Subjects with diabetes mellitus, hypertension, and/or dyslipidemia were classified as "metabolically unhealthy." The cohort was stratified into four groups according to obesity and metabolic healthiness: metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), MHO, and metabolically unhealthy obese (MUO).

RESULTS

AF was newly diagnosed in 5106 (1.3%) individuals during a mean follow-up of 7.5±1.5years. The AF incidence rates for the MHNO, MUNO, MHO, and MUO groups were 0.76, 2.66, 1.10, and 2.88 per 1000 person-years, respectively. Compared with the MHNO group, the MHO group had increased AF risk (adjusted hazard ratio, 1.30; 95% CI, 1.14-1.48) on multivariate analysis. One fourth of the MHO cohort became metabolically unhealthy, contributing to increased AF risk. Obesity was an independent risk factor for AF, and increased AF risk by 20%. Metabolic unhealthiness increased AF risk by around 40%, and of its components, hypertension contributed the most.

CONCLUSIONS

MHO individuals are at increased risk for AF development, and obesity was independently associated with elevated AF risk.