Cardiometabolic index: a new tool for screening the metabolically obese normal weight phenotype

PURPOSE

People with the metabolically obese normal weight (MONW) phenotype are considered as an extremely high-risk group for unfavorable health consequences, but they are frequently undetected due to deceptive body mass index (BMI) and complex assessment. This study aimed to explore the clinical usefulness of cardiometabolic index (CMI) in identifying MONW individuals.

METHODS

This cross-sectional study involved a total of 47,683 normal-weight subjects aged ≥ 18 years. Participants underwent anthropometrics, routine biochemical tests, and questionnaires for a full evaluation of the metabolic profile. The odds ratio (OR) of CMI and MONW phenotype was determined by the Logistic regression models and the diagnostic accuracy of CMI was evaluated by the receiver operating characteristic (ROC) curve analysis.

RESULTS

The prevalence of MONW phenotype was 11.0%. After multivariate adjustment, the ORs for MONW in the highest compared with the lowest quartile of CMI was 71.20 (95% CI 55.19-91.86), and 1-SD increment of CMI brought a 54% additional risk. In ROC analysis, compared with BMI and waist circumference, CMI showed superior performance for identifying MONW individuals with an AUC of 0.853 (95% CI 0.847-0.860) in men and 0.912 (95% CI 0.906-0.918) in women, respectively. Moreover, CMI exhibited the highest diagnostic accuracy in younger age groups (aged 18-34 for men; aged 18-34 and 35-44 for women), in which AUCs surpassed 0.9 in both sexes.

CONCLUSIONS

CMI could be served as a valuable indicator to identify MONW phenotype of Chinese adults, particularly for young people.

Metabolically healthy obesity and metabolically obese normal weight: a review

Despite the general relationship between obesity and its co-morbidities, there are both obese individuals who scarcely present the associated pathologies (metabolically healthy obese; MHO) and individuals who present obesity alterations despite having normal weight (metabolically obese normal weight; MONW). It is still difficult to define metabolically MHO and MONW individuals because different classifications have been used in the studies reported. Indeed, different inclusion criteria have been used to discriminate between metabolically healthy and metabolically unhealthy subjects. Due to this and other reasons, such as differences in ethnicity, genetics, and lifestyle of the populations, data concerning the prevalence of MHO and MONW are very variable. The main determinants of MHO are type of growth (hypertrophy or hyperplasia), anatomical location, inflammation of adipose tissue, ectopic fat accumulation, genetic factors, and lifestyles factors. In the case of MONW, the main determinants are genetic background and lifestyle factors. With regard to treatment, it is not clear whether MHO subjects would benefit from traditional lifestyle interventions, based on diet energy restriction and increased physical activity. For MONW subjects, there is still no specialized treatment, and the therapies are the same as those used in obese subjects.

Physiological and Lifestyle Traits of Metabolic Dysfunction in the Absence of Obesity

PURPOSE OF REVIEW

Individuals with metabolically unhealthy normal weight (MUNW) have an adverse cardiometabolic risk factor profile in the absence of excess body weight, and increased risk for diabetes and heart disease. We critically review some physiological traits and lifestyle characteristics of the MUNW phenotype.

RECENT FINDINGS

The prevalence of MUNW varies considerably around the world and among ethnicities, partly because of different definitions; on average, this phenotype affects about ~ 30% of normal weight persons globally. Most studies have recruited MUNW subjects who, although within the normal weight range, are significantly "more obese" than their metabolically healthy lean peers (greater body mass index or total body fat); hence one cannot ascertain whether observed differences are true traits of the MUNW phenotype of simply secondary to greater relative adiposity within the normal range. Carefully matched studies have indicated that MUNW can exist in the absence of excess total body fat. These subjects have a preferential accumulation of fat in the upper body (abdominal subcutaneous and visceral adipose tissues) and the liver, but not skeletal muscle; perhaps surprisingly, this predominantly "android" fat distribution does not translate into increased waist circumference. The MUNW phenotype is associated with lower aerobic fitness and muscle mass and strength, but whether this is simply due to inadequate regular physical activity is not entirely clear. Likewise, no consistent associations have been found between any dietary factors and the development of MUNW phenotype, but diet-induced modest weight loss facilitates its resolution. Delineating the mechanisms leading to metabolic dysfunction in the absence of increased body weight and body fat will likely reveal important targets for improving metabolic health and eventually for reducing the burden of cardiometabolic disease, not only in individuals with normal body weight but also in people with obesity.

Mediterranean diet, Dietary Approaches to Stop Hypertension (DASH) style diet, and metabolic health in U.S. adults

BACKGROUND & AIMS

There is sparse evidence on the relationship between the Mediterranean diet, Dietary Approaches to Stop Hypertension (DASH) style diet, and metabolic health, especially comparing cardiometabolic phenotypes among in normal weight and obese populations. We aimed to investigate the association of the Mediterranean diet scores (MDS) and DASH index with metabolically healthy obese (MHO) and metabolically obese normal weight (MONW) phenotypes in a representative U.S.

POPULATION

METHODS

MDS and DASH index were calculated using dietary data from 2767 adults aged 20-90 years without any prior diagnosis of cancer or cardiovascular disease from the National Health and Nutrition Examination Survey III, 1988-1994. MHO and MONW individuals were identified using fasting glucose, insulin resistance, blood pressure, triglycerides, C-reactive protein, and high-density lipoprotein-cholesterol.

RESULTS

Higher MDS was associated with higher odds of MHO phenotype (odds ratio (OR)_{T3 vs T1}, 2.57 [95% confidence interval (CI), 1.04-6.35]; P trend = 0.04), and higher DASH index was associated with lower odds of MONW phenotype (OR_{T3 vs T1,} 0.59 [95% CI, 0.38-0.93]; P trend = 0.03) only in the younger age group (<45 years for men or premenopausal women). No significant associations of MDS and DASH index with MHO and MONW phenotypes were observed in the older age group (≥45 years for men or postmenopausal women).

CONCLUSIONS

Adherence to Mediterranean diet or DASH style diet was favorably associated with MHO and MONW phenotypes only in the younger age group, suggesting that potential dietary intervention to prevent cardiometabolic disease differ by age group.

Obesity or obesities? Controversies on the association between body mass index and premature mortality

Obesity is still defined on the basis of body mass index (BMI) and BMI in itself is generally accepted as a strong predictor of overall early mortality. However, an inverse association between BMI and mortality has been reported in patients with many disease states and in several clinical settings: hemodialysis, cardiovascular diseases, hypertension, stroke, diabetes, chronic obstructive pulmonary disease, surgery, etc. This unexpected phenomenon is usually called obesity-survival paradox (OP). The contiguous concepts of metabolically healthy obesity (MHO, a phenotype having BMI ≥ 30 but not having any metabolic syndrome component and having a homeostasis model assessment of insulin resistance, HOMA, <2.5) and metabolically obese normal weight (MONW, normal-weight individuals displaying obesity-related phenotypic characteristics) have received a great deal of attention in recent years. The interactions that link MHO, MONW and OP with body composition, fat distribution, aging and cardiorespiratory fitness are other crucial areas of research. The article is an introductory narrative overview of the origin and current use of the concepts of MHO, MONW and OP. These phenomena are very controversial and appear as a consequence of the frail current diagnostic definition of obesity based only on BMI. A new commonly established characterization and classification of obesities based on a number of variables is needed urgently.

New obesity classification criteria as a tool for bariatric surgery indication

Obesity plays relevant pathophysiological role in the development of health problems, arising as result of complex interaction of genetic, nutritional, and metabolic factors. Due to the role of adipose tissue in lipid and glucose metabolism, and low grade inflammation, it is necessary to classify obesity on the basis of body fat composition and distribution, rather than the simply increase of body weight, and the Body Mass Index. The new term of adiposopathy (‘‘sick fat’’) clearly defines the pathogenic role of adipose tissue. Four phenotypes of obese individuals have been described: (1) normal weight obese (NWO); (2) metabolically obese normal weight; (3) metabolically healthy obese; and (4) metabolically unhealthy obese or “at risk” obese. Moreover, sarcopenic obesity has been related to all the phenotypes. The category of normal weight lean, represented by metabolically healthy normal weight has been classified to distinguish from NWO. It is crucial to recommend a bariatric surgery taking into account adiposopathy and sick fat that occurs with the expansion of fat mass, changing the inflammatory and metabolic profile of the patient. Body fat percentage and genetic polymorphism have to be evaluated to personalize the best bariatric surgery intervention.

Lipid accumulation product and visceral adiposity index are effective markers for identifying the metabolically obese normal-weight phenotype

AIM

Studies have identified the metabolically obese normal-weight (MONW) phenotype, which carries increased risk of diabetes and cardiovascular disease. We aimed to investigate the ability of lipid accumulation product (LAP) and visceral adiposity index (VAI), two markers of visceral obesity, to identify the MONW phenotype.

METHODS

Normal-weight participants [body mass index (BMI) being of 18.5-23 kg/m(2)] (n = 3,552; 46.9 % men) in the 2009 nationwide China Health and Nutrition Survey were included in our analysis. Four different criteria that have been published were used to define the MONW phenotype. LAP and VAI were calculated according to published formula.

RESULTS

Receiver operating characteristic (ROC) curve analysis revealed that, regardless of the definition used to define MONW phenotype, both LAP [area under the ROC curve (AUC) ranging from 0.606 to 0.807 depending on the criteria used for MONW phenotype] and VAI (AUC ranging from 0.611 to 0.835 depending on the criteria used for MONW phenotype) outperformed anthropometric parameters including BMI, waist circumference, waist-to-hip ratio, and waist-to-height ratio for identifying MONW phenotype. Both LAP and VAI were strongly related to the MONW phenotype, irrespective of the criteria used to define the MONW phenotype. The associations between the 4th quartile of LAP and the MONW phenotype or between the 4th quartile of VAI and the MONW phenotype were consistently seen in various subgroups.

CONCLUSION

Our study demonstrates that both LAP and VAI are effective markers for identifying the Chinese adults with MONW phenotype.

The concept of normal weight obesity

Individuals with normal body weight by body mass index (BMI) and high body fat percentage show a high degree of metabolic dysregulation. This phenomenon, defined as normal weight obesity, is associated with a significantly higher risk of developing metabolic syndrome, cardiometabolic dysfunction and with higher mortality. Recently, we have also shown that coronary artery disease patients with normal BMI and central obesity have the highest mortality risk as compared to other adiposity patterns. Therefore, it is important to recognize these high-risk groups for better adiposity-based risk stratification. There is a need for an updated definition of obesity based on adiposity, not on body weight.

Serum magnesium in the metabolically-obese normal-weight and healthy-obese subjects

BACKGROUND

Given that hypomagnesemia is related with hyperglycemia, hypertension, hypertriglyceridemia, and insulin resistance, the objective of this study was to determine whether serum magnesium levels are associated with the metabolically obese normal weight (MONW) and the metabolically healthy obese (MHO) phenotypes.

METHODS

Population-based cross-sectional study that enrolled 427 subjects, men and non-pregnant women aged 20 to 65years, to participate in the study. Subjects were allocated into groups with and without obesity; among non-obese individuals, the subgroup of MONW subjects was compared with a control group of healthy normal-weight individuals. Among obese individuals, the subgroup of MHO subjects was compared with a control group of obese subjects who exhibited at least one metabolic abnormality. In the absence of obesity, the presence of fasting hyperglycemia, insulin resistance, hypertriglyceridemia, and/or hypertension defined the presence of MONW phenotype. In the absence of hypertension, insulin resistance and metabolic abnormalities of fasting glucose and triglycerides levels, the phenotypically obese subjects were defined as MHO individuals.

RESULTS

The sex-adjusted prevalence of MONW and MHO phenotypes was 40.8% and 27.9%. The multivariate logistic regression model adjusted by family history of diabetes, age, body mass index, and waist-circumference, showed a positive association between hypomagnesemia and the MONW phenotype (OR 6.4; 95%CI 2.3-20.4) and negative relationship between serum magnesium and the MHO phenotype (OR 0.32; 95%CI 0.17-0.61).

CONCLUSIONS

Our results show that hypomagnesemia is positively associated with the presence of MONW phenotype, and the normomagnesemia negatively with the MHO phenotype.