Abdominal obesity: causal factor or simply a symptom of obesity-related health risk

Sechang Oh,1 Kiyoji Tanaka,2 Jin-won Noh,3 Rina So,2,4 Takehiko Tsujimoto,2 Hiroyuki Sasai,1,4 Mijung Kim,5 Junichi Shoda11Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan; 2Faculty of Health and Sports Science, University of Tsukuba, Tsukuba, Ibaraki, Japan; 3Department of Healthcare Management, Eulji University, Seongnam-si, Gyeonggi-do, Republic of Korea; 4Japan Society for the Promotion of Science, Tokyo, Japan; 5Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, JapanBackground: Abdominal fat (AF) reduction is advocated in the treatment of obesity-related diseases. Nonetheless, recent studies have shown additional beneficial effects against obesity-related health risks, independent of AF reduction. Therefore it is important to determine whether AF plays a causal role in promoting metabolic disorders or is simply a symptom of increased obesity-related health risk factors. Clarification of the primary role of AF in the pathogenesis of obesity-related disease is also important.Objective: This retrospective study was conducted with the objectives of 1) comparison between groups exhibiting equivalent amounts of AF loss that resulted from distinct treatments (exercise and dietary restriction) with respect to degrees of improvement in obesity-related health risk factors and 2) determination of definite differences in the outcomes of obesity-related health risk in subjects receiving identical treatment (exercise) but exhibiting a remarkable difference in AF reduction.Design: In 66 subjects who completed a 12-week exercise or dietary restriction program, 17 parameters (systolic blood pressure [SBP] and diastolic blood pressure [DBP]; high-sensitivity C-reactive protein [hs-CRP]; leptin, adiponectin, tumor necrosis factor [TNF]-α, interleukin [IL]-6; alanine aminotransferase [ALT], gamma glutamyl transpeptidase [γGT]; lipid profile: high-density lipoprotein cholesterol [HDLC], triglyceride [TG]; fasting plasma glucose [FPG], hemoglobin A1c [HbA1c], homeostasis model assessment of insulin resistance (HOMA-IR); creatinine, uric acid; and maximal aerobic capacity [VO2 max]) were examined as indicators of obesity-related health risk.Results: Despite equivalent magnitudes of AF reduction (-29.5% versus -30.1%) in subjects in the exercise and dietary restriction groups (objective 1), ten parameters (SBP, DBP, HDLC, HOMA-IR, uric acid, creatinine, hs-CRP, adiponectin, IL-6, and VO2 max) showed significant differences. However, for large AF reduction differences (-30.1% versus -2.8%) between groups of subjects in the same exercise program (objective 2), only creatinine and VO2 max were different.Conclusion: It is likely that AF reduction alone is not directly linked to improvement in obesity-related health risk factors, indicating the need for reexamination of the management for AF reduction (ie, lifestyle modification) rather than simply targeting reduction of AF.Keywords: exercise, dietary restriction, intervention study, lifestyle modification, metabolic syndrom