Impact of BMI on the incidence of metabolic abnormalities in metabolically healthy men

Abstract

OBJECTIVES: Although the existence of metabolically healthy obese (MHO) individuals has been recognized, little is known regarding metabolic health status in these subjects over time. Thus, we evaluated longitudinal changes in metabolic parameters among MHO subjects compared with metabolically healthy, normal-weight (MHNW) subjects. METHODS: A cohort study was performed on 2599 Korean men, 30 --59 years of age, with no evidence of fatty liver disease on ultrasound and no traits of metabolic syndrome at baseline. BMI was categorized based on criteria for Asian population. Study participants were followed annually or biennially between 2002 and 2009. At each visit, the fatty liver on ultrasound was assessed and metabolic abnormalities were measured. Parametric Cox models and a pooled logistic regression models were used to evaluate the relationships of BMI with incident metabolic abnormalities. RESULTS: During 9647.1 person-years of follow-up, 1673 participants developed metabolic abnormalities. After adjusting for age, smoking, alcohol intake and exercise, higher baseline BMI categories predicted increased incidences of metabolic abnormalities in a dose-response manner. The hazard ratios (95% confidence intervals) for hypertriglyceridemia, prediabetes, pre-hypertension, low high-density lipoprotein-cholesterol, fatty liver, elevated high sensitivity-C reactive protein, elevated homeostasis model assessment of insulin resistance, any metabolic abnormality and metabolic syndrome among the MHO subjects compared with the MHNW subjects were 1.51 (1. Keywords: body mass index; risk factors; insulin resistance; metabolic syndrome X; follow-up studies INTRODUCTIONObesity is a risk factor for cardiometabolic disorders such as type 2 diabetes mellitus and cardiovascular disease. 1,2 However, the incidence of obesity-related metabolic disturbances varies widely among obese individuals. 3,4 A unique subset of obese individuals that appears to be protected from obesity-related metabolic abnormalities has been identified. 3,5 These individuals, referred to as metabolically healthy but obese (MHO), are relatively insulin sensitive and have a favorable cardiovascular risk profile despite excessive body fat. 6 Previous studies indicate that MHO individuals, regardless of body mass index, are not at increased risk for cardiovascular diseases compared with normal-weight subjects without insulin resistance. 7,8 Therefore, weight loss may not be deemed necessary among these individuals.Recent longitudinal studies have observed that obese men without metabolic syndrome were at an increased risk for cardiovascular events or death compared with normal-weight individuals without metabolic syndrome. 9,10 Other studies observed that the MHO subset had an intermediate cardiovascular risk between healthy non-obese subjects and insulin resistant subjects. 11,12 Furthermore, recent intervention studies showed that lifestyle-induced weight loss among MHO individuals was associated with improved insulin sensitivity. 13,14

Metabolically Healthy Obesity and the Development of Nonalcoholic Fatty Liver Disease

“…Indeed, the expression of infl ammatory genes was similarly altered in both MHO and metabolically unhealthy obese subjects, highlighting that MHO individuals may exhibit an adverse profi le comparable with that of metabolically unhealthy obese patients and that the MHO concept should be applied with caution ( 35 ). Finally, recent studies suggest that the MHO phenotype is transient and progresses to overt metabolic abnormalities in a signifi cant proportion of individuals ( 36,37 ), although the association between BMI and incident NAFLD in our study was evident across all BMI levels and was not restricted to MHO participants. Further mechanistic studies, however, are needed to further understand why the MHO phenotype is associated with an increased incidence of NAFLD.…”

Increased Cardiometabolic Risk Factors and Inflammation in Adipose Tissue in Obese Subjects Classified as Metabolically Healthy

“…Some authors consider the appearance of metabolic abnormalities and other comorbidities associated with obesity to be only a matter of time; i.e., it is merely a question of evolution of the disease as evidenced by studies showing that MHO subjects exhibit increased risk of developing diabetes, hypertension, or metabolic syndrome in the long term (41,42). In this sense, a growing number of studies have questioned the apparently healthy metabolic condition of MHO, showing that these obese patients have increased morbidity and mortality as compared whiskers showing from minimum to maximum.…”

Trends in Cardiovascular Health Metrics in Obese Adults: National Health and Nutrition Examination Survey (NHANES), 1988–2014

“…Obese participants who are free from cardiometabolic disease risk factors are termed “metabolically healthy obese.”9, 26 The existence of the metabolically healthy obese condition has been controversial27, 28, 29, 30; however, we have recently added some clarification to this issue by pointing out that conclusions rest heavily on the definition of metabolically healthy obese 31. We4, 5, 10 and others12, 13, 14 have shown that 1 or 2 metabolic syndrome traits confer increased risk of diabetes mellitus and CVD outcomes and that such persons are relatively insulin resistant.…”