Association of normal weight obesity with lifestyle and dietary habits in young Thai women: A cross-sectional study

Background

The risk of lifestyle-related diseases in normal weight obesity (NWO), a condition, in which the body mass index (BMI) is normal but the body fat mass is high, has attracted a lot of attention. However, there are no reports on the association between NWO and lifestyle, eating habits, and other health risks in Thai people. BMI alone cannot be used to identify individuals with NWO; thus, some students with NWO develop metabolic abnormalities without receiving any intervention. This study aimed to examine the differences in anthropometrics, lifestyle, and eating habits among young Thai women and their association with the BMI and the body fat ratio (BFR).

Methods

A total of 250 female Thai university students of normal body type (18.5 ≤ BMI<25.0 kg/m2) were classified as having non-normal weight obesity (NO-NWO) if their BFR was <30.0% or NWO if their BMI and BFR were >30.0%. The lifestyle and eating habits of the two groups were compared. We conducted logistic analysis with the presence or absence of NWO as the dependent variable, and the dietary habit items of "eating greasy foods," "eating ultra-processed foods (UPF)," and "drinking sweetened beverages" as the objective variables.

Results

Among the study participants who were of normal body type, 46.8% were NWO. The participants in the NWO group consumed UPF more frequently (odds ratio [OR], 2.04; p = 0.014) and sweetened beverages more regularly (OR, 1.92, p = 0.041) than those in the NO-NWO group.

Conclusion

UPF and sweetened beverage consumption was more common in individuals with NWO. Identifying the risk factors for NWO is essential to help individuals make lifestyle changes to prevent its progression and complications.

Knockout of TSC2 in Nav1.8+ neurons predisposes to the onset of normal weight obesity

OBJECTIVE

Obesity and nutrient oversupply increase mammalian target of rapamycin (mTOR) signaling in multiple cell types and organs, contributing to the onset of insulin resistance and complications of metabolic disease. However, it remains unclear when and where mTOR activation mediates these effects, limiting options for therapeutic intervention. The objective of this study was to isolate the role of constitutive mTOR activation in Nav1.8-expressing peripheral neurons in the onset of diet-induced obesity, bone loss, and metabolic disease.

METHODS

In humans, loss of function mutations in tuberous sclerosis complex 2 (TSC2) lead to maximal constitutive activation of mTOR. To mirror this in mice, we bred Nav1.8-Cre with TSC2fl/fl animals to conditionally delete TSC2 in Nav1.8-expressing neurons. Male and female mice were studied from 4- to 34-weeks of age and a subset of animals were fed a high-fat diet (HFD) for 24-weeks. Assays of metabolism, body composition, bone morphology, and behavior were performed.

RESULTS

By lineage tracing, Nav1.8-Cre targeted peripheral sensory neurons, a subpopulation of postganglionic sympathetics, and several regions of the brain. Conditional knockout of TSC2 in Nav1.8-expressing neurons (Nav1.8-TSC2KO) selectively upregulated neuronal mTORC1 signaling. Male, but not female, Nav1.8-TSC2KO mice had a 4-10% decrease in body size at baseline. When challenged with HFD, both male and female Nav1.8-TSC2KO mice resisted diet-induced gains in body mass. However, this did not protect against HFD-induced metabolic dysfunction and bone loss. In addition, despite not gaining weight, Nav1.8-TSC2KO mice fed HFD still developed high body fat, a unique phenotype previously referred to as 'normal weight obesity'. Nav1.8-TSC2KO mice also had signs of chronic itch, mild increases in anxiety-like behavior, and sex-specific alterations in HFD-induced fat distribution that led to enhanced visceral obesity in males and preferential deposition of subcutaneous fat in females.

CONCLUSIONS

Knockout of TSC2 in Nav1.8+ neurons increases itch- and anxiety-like behaviors and substantially modifies fat storage and metabolic responses to HFD. Though this prevents HFD-induced weight gain, it masks depot-specific fat expansion and persistent detrimental effects on metabolic health and peripheral organs such as bone, mimicking the 'normal weight obesity' phenotype that is of growing concern. This supports a mechanism by which increased neuronal mTOR signaling can predispose to altered adipose tissue distribution, adipose tissue expansion, impaired peripheral metabolism, and detrimental changes to skeletal health with HFD - despite resistance to weight gain.

Association between relative fat mass, uric acid, and insulin resistance in children with chronic kidney disease

INTRODUCTION

This cross-sectional study investigates the association between insulin resistance (IR) and serum uric acid (sUA) and relative fat (RFM) and lean mass (RLM) profiles in children with chronic kidney disease (CKD).

MATERIAL AND METHODS

RLM and RFM were assessed by bioimpedance spectroscopy in 41 children and adolescents. Normal weight obesity (NWO) was defined as normal height-age body mass index and RFM >85th percentile, according to age and sex. Homeostatic model assessment of insulin resistance (HOMA-IR) level >95th percentile, according to sex and pubertal stage, and sUA >7 mg/dl were used to define IR and hyperuricemia, respectively.

RESULTS

High RFM (15 patients) and NWO (7 patients) were associated with higher HOMA-IR in total (p < 0.001) and normal-weight patients (p = 0.004), respectively. RFM was positively and RLM negatively correlated to HOMA-IR (rs = 0.500, p = 0.001 and rs = -0.539, p < 0.001, respectively) and sUA (rs = 0.370, p = 0.017 and rs = -0.325, p = 0.038, respectively), while sUA was positively correlated to HOMA-IR (rs = 0.337, p = 0.031). Hyperuricemia (16 patients) was positively associated with higher RFM and HOMA-IR (p = 0.001 and p = 0.010, respectively). The correlation between sUA and HOMA-IR lost significance after adjustment for RFM. In logistic regression analysis, a 5% increase in RFM was associated with IR (11 patients) independently of the age, sex, sUA, and CKD stage in both total (OR 2.174, 95% CI 1.115-4.225) and normal-weight (OR 3.504, 95% CI 1.110-11.123) patients.

CONCLUSION

Children with high RFM, including those presenting NWO, are at risk for IR regardless of CKD stage. RFM is probably the mediator of the link between sUA and IR.

Association of adipocytokines with lipid and glycemic profiles in women with normal weight obesity

BACKGROUND

Individuals with normal weight obesity (NWO) are predisposed to having cardiometabolic disorders. This study aims to investigate the circulating levels of vaspin, leptin and their association with glycemic and lipid profiles in women with NWO.

METHODS

Forty women with body mass index (BMI) = 18.5-24.9 kg/m2 and fat mass (FM) ≥ 30% were assigned in the NWO group. Thirty age-matched women with identical BMI range, and FM < 30% (normal weight non-obese; NWNO) were considered as a control group. In addition to anthropometric measurements, glycemic and lipid profiles and circulating levels of leptin and vaspin were measured.

RESULTS

The mean ± standard deviation (SD) age of participants was 28.76 ± 4.76 years in the NWO group and 29.23 ± 4.50 years in the control group. The NWO group had the higher mean serum levels of insulin (9.02 ± 4.75 vs. 6.24 ± 2.51, P = 0.009), leptin (17.31 ± 8.10 vs. 9.94 ± 4.30, P < 0.001) and homeostatic model assessment of insulin resistance (HOMA-IR) (33.77 ± 20.71 vs. 23.48 ± 10.03, P = 0.009) compared to the NWNO group. The serum level of vaspin was higher in the NWO group compared to the control group (34.82 pg/ml vs. 27.72 pg/ml, respectively, P = 0.12). In NWO group, the serum levels of leptin had positive correlation with FBS (r = 0.45, P = 0.02), insulin (r = 0.51, P = 0.008), and HOMA-IR (r = 0.46, P = 0.02) and vaspin concentration was associated with insulin (r = 0.36, P = 0.02) and HOMA-IR (r = 0.30, P = 0.06), positively.

CONCLUSION

It is concluded that the concentration of insulin and HOMA-IR index were significantly higher in women with NWO compared to NWNO. Higher concentrations of leptin and vaspin in the NWO group were associated with glycemic profile.

Conjugated linoleic acid supplements preserve muscle in high-body-fat adults: A double-blind, randomized, placebo trial

BACKGROUND AND AIMS

Conjugated linoleic acid (CLA) has been used to improve body composition in weight management. However, clinical trial results are inconsistent and limited among Asians. We aimed to investigate the effect of CLA on body composition of Chinese adults with elevated body fat percentage.

METHODS AND RESULTS

In this double-blind, randomized, placebo-controlled trial, 66 Chinese adults (aged 18-45 years old, 37.9% male) with elevated body fat percentage were provided with 3.2 g/day CLA (n = 33) or 3.2 g/day placebo (sunflower oil; n = 33) for 12 weeks. Both groups received lifestyle counseling, featured with low fat and low sugar diet, and moderate physical activity. Body composition was measured using dual-energy X-ray absorptiometry at the baseline and end of the trial. Sixty-four participants finished this study. Compared with the placebo group, the CLA group showed increased trunk muscle mass (MM) (0.6 ± 1.7 vs. -0.3 ± 1.2 kg, P = 0.019). Among those with an adherence score higher than 0.80 (n = 56, 87.5%), a greater increase in both total and trunk MM was observed in the CLA group (both P < 0.05). Moreover, the effect on MM appeared to be more evident in men, those with a body mass index <25 kg/m², or those with higher self-rated physical activity.

CONCLUSIONS

In Chinese adults with elevated body fat percentage, 3.2 g/day CLA supplementation may be effective in preserving MM, especially in the trunk region.

REGISTRATION

This study was registered at ClinicalTrials.gov as NCT03915808 on April 9, 2019.

Early life high-fat diet exposure evokes normal weight obesity

Obesity is becoming one of the most severe global health problems. However, risk of developing normal weight obesity, where an individual has a high percentage of body fat despite a normal body mass index, is gaining attention since such individuals also develop systemic inflammation and metabolic dysregulation.

In this study, juvenile (3-week-old) and adult (8-week-old) rats were fed a high fat diet (HFD) for 9 weeks and compared them with normal chow diet (NCD) fed rats. The HFD fed adult group showed increase in energy intake, body weight (BW), total fat, visceral fat and subcutaneous fat compared with an age-matched NCD group. In addition, the percentage of muscle mass to BW in the adult HFD group was significantly lower compared with the NCD group. When HFD feeding was started from the juvenile stage, there were almost no differences in energy intake and BW between the HFD and NCD groups. However, the juvenile HFD group showed a 1.7-fold increase in total fat, visceral fat and subcutaneous fat compared with their age-matched NCD group. The percentage of muscle mass to BW was significantly lower in the juvenile HFD group compared with the NCD group. In addition, increased plasma insulin levels and decreased insulin sensitivity was observed only in juvenile HFD group, but not in adult HFD group. These results suggest that HFD feeding in growth period induces insulin resistance and normal weight obesity.

Here we show a method for generating a normal weight obesity model, as well as raising the alarm for developing normal weight obesity when children are exposed to high-fat meals.

Normal Weight Obesity: An Underrecognized Problem in Individuals of South Asian Descent

PURPOSE

Obesity has attained pandemic proportions across the world, and its prevalence in developing countries is also on the rise. Nevertheless, there is still a large gap in understanding the reasons behind a disproportionately high prevalence of diabetes as opposed to a lesser degree of obesity seen in individuals of South Asian origin. This research letter highlights the importance of identifying individuals with normal weight obesity, which may partially bridge this knowledge gap.

METHODS

We reviewed recently published evidence on normal weight obesity.

FINDINGS

Normal weight obesity is a common public health problem and may be prevalent in up to one-third of individuals of certain Asian ethnicities. Literature is emerging on its pathophysiology and association with metabolic diseases, such as type 2 diabetes mellitus, hypertension, and dyslipidemia. More recently, normal weight obesity was also identified as an independent strong predictor of cardiovascular mortality. However, evidence is particularly lacking on its appropriate management.

IMPLICATIONS

Normal weight obesity is an underrecognized yet widely prevalent problem in individuals of Asian descent. Further research on pathogenic mechanisms, diagnostic modalities, and therapeutic options in individuals with normal weight obesity is needed to appropriately manage this condition.

Prevalence and cardiometabolic risks of normal weight obesity in Chinese population: A nationwide study

BACKGROUND AND AIMS

Several studies have reported increased cardiovascular risks in normal weight obesity (NWO) populations. We aimed to investigate the prevalence of NWO and its relationships with cardiometabolic risks in Chinese patients.

METHODS AND RESULTS

The data were from the 2007-2008 China National Diabetes and Metabolic Disorders Study. The body fat (BF) was measured using the biological impedance method. NWO was defined as a normal BMI (18.5-23.9 kg/m²) but with excess BF% (BF% ≥ 24% for men and ≥33% for women). 23,748 people (9633 males and 14,115 females) were enrolled and the prevalence of NWO was 9.5% for men, 6.06% for women. The prevalence risks of diabetes (odds ratio [OR]1.519, 95% confidence interval [CI] 1.262-1.828), Framingham risk score (FRS) ≥10% (OR 1.973, 95% CI 1.596-2.439), hypertension (OR 1.525, 95% CI 1.333-1.745), and metabolic syndrome Mets (OR 2.175, 95% CI 1.920-2.463) significantly increased in the NWO group compared with the normal group. Subgroup analyses showed that, after ruling out participants with abnormal waist circumference, the male group had similar findings to the overall population; but in the female group, the prevalence risks of FRS ≥10%, hypertension, and Mets increased, although the risk of diabetes did not.

CONCLUSION

NWO is in a relatively high prevalence in Chinese population, and the prevalence of NWO is higher in Chinese men compared to Chinese women. Cardiometabolic risks significantly increase in an NWO population, and such risks persist after excluding the effect of abdominal obesity.

Heterogeneity of gestational diabetes (GDM) and long-term risk of diabetes and metabolic syndrome: findings from the RADIEL study follow-up

AIMS

To assess the metabolic health of obese and non-obese women at high GDM risk 5 years postpartum.

METHODS

This is a secondary analysis of the 5-year follow-up of the RADIEL GDM prevention study including 333 women at high GDM risk (BMI ≥ 30 kg/m² and/or previous GDM). Five years postpartum metabolic health was assessed including anthropometric measurements, oral glucose tolerance test, lipid metabolism, and body composition as well as medical history questionnaires. For the analysis, we divided the women into four groups based on parity, BMI, and previous history of GDM.

RESULTS

Five years postpartum impaired glucose regulation (IFG, IGT, or diabetes) was diagnosed in 15% of the women; 3.6% had type 2 diabetes. The highest prevalence was observed among obese women with a history of GDM (26%), and the lowest prevalence (8%) among primiparous obese women (p = 0.021). At follow-up 25-39% of the obese women fulfilled the diagnostic criteria for the metabolic syndrome, in the non-obese group 11% (p < 0.001). This was associated with body fat percentage. The non-obese group, however, faced metabolic disturbances (IFG, IGT, diabetes, or metabolic syndrome) at a significantly lower BMI (p < 0.001). Among women who were non-obese before pregnancy, 5 years postpartum, the obesity prevalence based on BMI was 14% and based on body fat percentage 58%.

CONCLUSIONS

The prevalence of impaired glucose regulation and metabolic syndrome is high 5 years postpartum among women at high risk of GDM. There are high-risk women also among the non-obese, who develop metabolic derangements already at a lower BMI.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.com , NCT01698385.

Association of serum complement C3 with metabolic syndrome components in normal weight obese women

BACKGROUND

Increased serum complement C3 has been related to body fat mass, metabolic syndrome and chronic diseases. The purpose of this study was to evaluate the levels of C3 in the subjects of normal weight obese (hereafter NWO) as well as their possible relationships with metabolic syndrome and inflammation.

METHODS

In this case-control study, 40 obese women with normal weight (body mass index (BMI) = 18.5-24.9 kg/m2) and body fat percentage above 30% (fat mass (FM) > 30%) and 30 non-obese women (BMI = 18.5-24.9 kg/m2) and fat percentage less than 25% (FM < 25%) were selected as the study sample. Body composition was analyzed using Bio Impedance analyzer. Blood samples were then collected and analyzed for fasting serum concentration of lipid components of metabolic syndrome, insulin, serum complement C3 and High sensitivity C reactive protein (hsCRP).

RESULTS

Mean waist and hip circumferences in NWO was higher than non-NWO (74.78 ± 4.81 versus 70.76 ± 2.91 and 99.12 ± 4.32 versus 93.16 ± 2/91, respectively, P-value < 0.001). However, the mean waist-to-hip ratio did not differ significantly (p = 0.448). The mean fasting serum concentration of complement C3, hsCRP and insulin was higher in NWO compared to that in non-NWO (P-value < 0.05). Moreover, insulin sensitivity in NWO was lower than that in non-NWO (0.357 versus 0.374, p-value = 0.043). Moreover, a significant correlation was found between body fat percentage and fasting serum complement C3 and insulin concentration (r = 0.417 and r = 0.254, p-value < 0.005, respectively).

CONCLUSION

Obese women with normal body mass index but high body fat percentage have higher serum C3 and are at a higher risk for metabolic dysregulation and metabolic syndrome than the healthy non-obese subjects.

Association of circulating irisin levels with normal weight obesity, glycemic and lipid profile

Background

Irisin, a recently identified myokine/adipokine, has potential role in type 2 diabetes and obesity. Normal weight obesity (NWO) is associated with a significantly higher risk of developing metabolic syndrome and cardiometabolic dysfunction. The aim of this study was to investigate association of irisin level with NWO, glycemicand lipid profile in women.

Methods

In this matchedcase-control study, 38 subjects with NWO (body mass index (BMI) <25 kg/m2 and BF % > 30) as case and 26 controls (BMI <25 kg/m2 and BF % < 30) were selected randomly from sport clubs in the East area of Tehran, Iran. In addition to anthropometric variables, including BMI and body composition, fasting blood sugar (FBS), fasting levels of irisin andinsulin, triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol were measured. All statistical analyses were performed with SPSS 18.0.

Results

In univariate analysis, levels of irisin were significantly higher in subjects with NWO compared to controls (0.81 ± 0.41vs. 0.58 ± 0.26 ng/ml, P = 0.009). This association remained significant after adjusting for confounders (adjusted for energy intake, physical activity, waist circumference and BMI) (P = 0.049). In NWO, irisin level was not significantly correlated with all glycemic and lipid profile. In control group, only correlation ofirisin with insulin was statistically significant (P = 0.03).

Conclusion

Serum irisin levels were higher in NWO subjects than controls. In control group, only the negative association between irisin and insulin levels was statistically significant. Further studies with larger sample size are clearly needed to evaluate the potential role of irisin in NWO subject and other disturbed metabolic conditions.

Normal weight adiposity in a Swedish population: how well is cardiovascular risk associated with excess body fat captured by BMI?

OBJECTIVE

The aim of this study was to examine how well body mass index (BMI) reflects cardiovascular risk associated with excess adiposity in a Swedish population by examining the association between body fat, BMI and cardiovascular risk factors.

METHODS

A total of 3,010 adults participated. Normal weight adiposity was defined as the combination of BMI < 25 kg/m2 and percentage body fat ≥35% for women and ≥25% for men. Associations with blood pressure, blood lipids, apolipoproteins and C-reactive protein were analysed in age-adjusted regression models.

RESULTS

The majority of the individuals with overweight and obesity were correctly classified to adiposity, while a wide range of body fat was observed among the normal weight subjects. In total, 9% of the participants were categorised as normal weight with adiposity. Compared with the normal weight leanness group, participants with normal weight adiposity had higher levels of serum triglycerides, low-density lipoprotein cholesterol, C-reactive protein, apolipoptotein B and the apolipoprotein B/A-I ratio. In normal weight men, adiposity was also associated with higher blood pressure and lower high-density lipoprotein cholesterol.

CONCLUSIONS

Higher percentage of body fat was associated with less favourable risk factor profile even in subjects who were normal weight. Thus, it might be relevant to screen for metabolic risk factors in the upper end of the normal weight category.

Cardiometabolic risks profile of normal weight obese and multi-ethnic women in a developing country

OBJECTIVES

To determine the prevalence of normal weight obesity among multi-ethnic women in Peninsular Malaysia and examine its associations with cardiometabolic risks and lifestyle behaviours.

METHODS

This was a cross-sectional study involving women recruited via multi-stage sampling from six states in Malaysia. Anthropometric and body composition analysis were performed. Normal weight obese (NWO) was defined as normal body mass index for Asians and the highest tertile of % body fat (BF). Biochemical measurements included fasting lipid and blood glucose levels. Metabolic syndrome was diagnosed based on the Harmonization criteria. Participants completed self-reported questionnaires that included physical activity, smoking, alcohol consumption, fruit and vegetable intake and sleep duration.

MAIN OUTCOME MEASURE

Body mass index, %BF, cardiometabolic risk factors, lifestyle behaviours.

RESULTS

A total of 6854 women were recruited and the prevalence of NWO was 19.8% (95% CI: 17.3-22.5). NWO was more prevalent among the Indians and older women. NWO women had higher odds for abdominal obesity (OR: 2.64, 95% CI: 1.73-4.04), hypertriglyceridemia (2.51, 1.47-4.29) and hypertension (1.63, 1.15-2.31) compared to women with lower % body fat after adjusted for age and ethnicity. The prevalence of metabolic syndrome among NWO women was 5.4% (95% CI: 3.0-9.8). None of the lifestyle behaviours were significantly associated with NWO.

CONCLUSIONS

Women with NWO had cardiometabolic abnormalities including abdominal obesity, dyslipidaemia and increased blood pressure. Health promotion efforts should include NWO women who may be oblivious of their deleterious health risks.

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.