This study was conducted among overweight and obese Iranian women between the ages of 18–50 years, with a BMI ≥ 25 kg/m2. The metabolic risk was assessed according to Karelis criteria and subjects classified as either MHO or MUO. Of the 241 subjects, 73.03% were classified as MUO with 7.88% as SO. We found that individuals with high FFM and high SMM to have a significantly low risk of MUO phenotype. We also found a significant positive correlation between sarcopenic obesity and MUO phenotype after all potential covariates were controlled.
This study’s MUO phenotypes showed a significantly higher BFM, VFM, FFM, SMM, and FMI than the MHO group. Previous studies have found that MUO women had significantly higher BFM, VFM, and muscle mass than MHO women [21] and healthy obese people [29].
Despite the fact that some studies [6, 22, 23] have observed a non-significant difference in the measures of adiposity in “healthy” and “unhealthy” phenotypes, in line with other previous studies [7, 24], we observed a significant increase in BFM in the MUO phenotype even after all potential confounders were controlled for. BFM has been reported as an independent predictor of insulin resistance and dyslipidemia [25] among postmenopausal women. Higher BFM has also been reported as an increased risk factor for type 2 diabetes [26, 27], as well as increase metabolic risk and the risk of cardiovascular disease [28, 29] in both gender. Furthermore, researches have shown increasing BFM to be correlated with an increase in FBG, triglyceride, LDL, and total cholesterol, and a decrease in HDL cholesterol [30, 31].
There have also been conflicting results regarding SMM accumulation among the metabolic phenotypes. While in some studies no significant differences in SMM indices between metabolic phenotypes of either obese or non-obese postmenopausal women [23] were found, some studies have reported SMM to significantly increase in the MUO phenotype of postmenopausal women [8, 32], and significantly decrease in the metabolic non-obese phenotype of young women (5). Estrella et al., [33] among Hispanic/Latino women found higher SMM to be independently associated with a lower prevalence of the MHO phenotype. In our study, each increase of 1-SD in skeletal muscle mass was associated with a lower prevalence of the MUO phenotype. Our result is in line with the fourth and fifth Korean National Health and Nutrition Examination Survey which reported a protective association of muscle mass with metabolic syndrome [34]. Additionally, in a 7-year retrospective cohort study, Kim and colleagues [35] found that an increase in relative skeletal muscle mass over time has a potential preventive effect on developing metabolic syndrome, independently of baseline skeletal muscle mass and glycometabolic parameters. In a nationally representative sample of 4,449 US adults aged 50 years and older from the NHANES surveys, Li and associates [36] found that only participants with low muscle mass but without metabolic syndrome had a significantly increased risk of all-cause mortality.
After we adjusted for all potential confounders, each increase of 1-SD in sarcopenic obesity was observed to be associated with a higher prevalence of MUO phenotype in the current study. In line with previous epidemiological studies, reports have shown that the odds of metabolic syndrome was 6 to 8 times higher in postmenopausal Korean women, elderly Korean men and women, and adult Caucasian subjects with sarcopenic obesity (SO) compared to those without sarcopenic obesity [14, 37–39]. Furthermore, Kim et al., [40] reported an increased risk of metabolic syndrome in subjects with sarcopenic obesity. In their study, compared with normal subjects, they found that SO subjects had significantly higher values for a number of metabolic syndrome components. Furthermore, they found SO to be independently associated with metabolic syndrome among women after adjustment for age.