Lee S, Deldin AR, White D, Kim Y, Libman I, Rivera-Vega M, Kuk JL, Sandoval S, Boesch C, Arslanian S. Aerobic exercise but not resistance exercise reduces intrahepatic lipid content and visceral fat and improves insulin sensitivity in obese adolescent girls: a randomized controlled trial. Am J Physiol Endocrinol Metab 305: E1222-E1229, 2013. First published September 17, 2013; doi:10.1152/ajpendo.00285.2013.-It is unclear whether regular exercise alone (no caloric restriction) is a useful strategy to reduce adiposity and obesity-related metabolic risk factors in obese girls. We examined the effects of aerobic (AE) vs. resistance exercise (RE) alone on visceral adipose tissue (VAT), intrahepatic lipid, and insulin sensitivity in obese girls. Forty-four obese adolescent girls (BMI Ն95th percentile, 12-18 yr) with abdominal obesity (waist circumference 106.5 Ϯ 11.1 cm) were randomized to 3 mo of 180 min/wk AE (n ϭ 16) or RE (n ϭ 16) or a nonexercising control group (n ϭ 12). Total fat and VAT were assessed by MRI and intrahepatic lipid by proton magnetic resonance spectroscopy. Intermuscular AT (IMAT) was measured by CT. Insulin sensitivity was evaluated by a 3-h hyperinsulinemic (80 mU·m 2 ·min Ϫ1 ) euglycemic clamp. Compared with controls (0.13 Ϯ 1.10 kg), body weight did not change (P Ͼ 0.1) in the AE (Ϫ1.31 Ϯ 1.43 kg) and RE (Ϫ0.31 Ϯ 1.38 kg) groups. Despite the absence of weight loss, total body fat (%) and IMAT decreased (P Ͻ 0.05) in both exercise groups compared with control. Compared with control, significant (P Ͻ 0.05) reductions in VAT (⌬Ϫ15.68 Ϯ 7.64 cm 2 ) and intrahepatic lipid (⌬Ϫ1.70 Ϯ 0.74%) and improvement in insulin sensitivity (⌬0.92 Ϯ 0.27 mg·kg Ϫ1 ·min Ϫ1 per U/ml) were observed in the AE group but not the RE group. Improvements in insulin sensitivity in the AE group were associated with the reductions in total AT mass (r ϭ Ϫ0.65, P ϭ 0.02). In obese adolescent girls, AE but not RE is effective in reducing liver fat and visceral adiposity and improving insulin sensitivity independent of weight loss or calorie restriction. insulin sensitivity; intrahepatic lipid; visceral fat; exercise; adolescents THE EPIDEMIC RATE OF CHILDHOOD OBESITY is a major health concern in the US, as overweight and obese youth are at increased risk of developing comorbidities such as nonalcoholic fatty liver disease (35), type 2 diabetes (33), and metabolic syndrome (21, 41), once considered diseases of adulthood. Although both diet and physical activity are considered to be the first lines of approach to treat obese youth (9), we recently reported that, in obese adolescent boys, increasing physical activity alone, independent of calorie restriction, is beneficial to reduce total fat, visceral adiposity, and intrahepatic lipid and improves cardiorespiratory fitness (CRF) (22). In obese adolescent girls, the utility of exercise alone as a strategy for reducing obesity-related metabolic risk factors is currently unclear. Given the lower physical activity levels in girls than in boys (14) and the fact that physical activi...

This study aimed to validate body composition analysis using bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) in children with obesity and to compare agreement between BIA and DXA according to their degree of obesity. Three hundred and sixteen children aged 6-17 years participated in the Intervention for Childhood and Adolescents Obesity via Activity and Nutrition study. We divided participants by body mass index (BMI) percentile (group 1: mild to moderate obesity; group 2: severe obesity) and compared body composition variables, eg, percentage of body fat (%BF), fat mass (FM), and fat-free mass (FFM) using BIA and DXA. The %BF and FM of BIA were significantly lower (-1.8% and -0.8 kg, respectively), and the FFM of BIA was significantly higher (1.4 kg) than those of DXA. There were significant negative relationships between the absolute value of differences from BIA and DXA and BMI z-scores in %BF, FM, and FFM (regression coefficient [β]: -1.39, 95% confidence interval [CI]: -1.81 to -0.97; β: -0.34, 95%CI: -0.61 to -0.06; β: -0.73, 95%CI: -1.03 to -0.44, respectively). The gap of body compositions between BIA and DXA decreased as participants became more obese, and the differences of FM in boys with severe obesity and the differences of %BF and FFM in girls with severe obesity were much less than those in children with mild to moderate obesity. In conclusion, the agreement between DXA and BIA was better for children with severe obesity than for children with mild to moderate obesity.

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As with the dramatic increases in childhood obesity over the past decades, the incidence of type 2 diabetes has increased among children and adolescents in the United States. Insulin resistance is a common feature of childhood obesity and increases the risk of type 2 diabetes, metabolic syndrome, and atherogenic lipoprotein profile in obese youth. Although cross-sectional studies report beneficial effects of physical activity or cardiorespiratory fitness on insulin sensitivity, the role of regular exercise alone (e.g., no calorie restriction) as a strategy to reduce the risk of type 2 diabetes is unclear in obese children and adolescents. In this mini review, we examined the independent effects of various exercise on glucose tolerance and insulin sensitivity in obese youth.

BackgroundLow levels of physical activity (PA) are strongly associated with the development of metabolic syndrome (MetS) and chronic diseases. However, few studies have examined this association in Koreans. The primary purpose of this study was to examine the associations between PA and MetS risks in Korean adults.MethodsA total of 1,016 Korean adults (494 males and 522 females) participated in this study. PA levels were assessed using the International PA Questionnaire. MetS risk factors were determined using clinically established diagnostic criteria.ResultsCompared with the highest PA group, the group with the lowest level of PA was at greater risk of high triglyceride (TG) in males (odds ratio [OR], 1.87; 95% confidence interval [CI], 1.07 to 3.24) and of hemoglobin A1c ≥5.5% in females (OR, 1.75; 95% CI, 1.00 to 3.04) after adjusting for age and body mass index. Compared with subjects who met the PA guidelines, those who did not meet the guidelines were more likely to have low high density lipoprotein cholesterol in both males (OR, 1.69; 95% CI, 1.11 to 2.58), and females (OR, 1.82; 95% CI, 1.20 to 2.77). Furthermore, those who did not meet the PA guidelines were at increased risk of high TG levels in males (OR, 1.69; 95% CI, 1.23 to 2.86) and abnormal fasting glucose (OR, 1.93; 95% CI, 1.17 to 3.20) and MetS (OR, 2.10; 95% CI, 1.15 to 3.84) in females.ConclusionIncreased levels of PA are significantly associated with a decreased risk of abnormal MetS components.