成年女性肥胖的影響因素：呼吸交換率、心率變異性、身體意象

Abstract

研究背景與目的：世界各國的肥胖盛行率逐年增加，因此積極推動肥胖防治工作已是刻不容緩的健康議題。造成肥胖的原因很多，例如飲食不均衡、缺乏體能活動、心理因素、基因等各種可改變和難以改變的因素。目前世界肥胖相關學會已經建議肥胖分級防治策略指引，基本上是採取飲食控制結合運動的生活型態介入來改善肥胖，但實證資料顯示介入成效不一。由於肥胖是多重危險因子造成的，探討肥胖的危險因子有助於提供更多減肥介入計畫的選擇。先前的研究顯示，交感神經活動降低可能會造成肥胖；另外肥胖男性的呼吸交換率較高，代表他們較傾向於利用碳水化合物作為能量來源，故油脂無法被有效消耗並囤積於體內。此外，相較於其他種族，亞裔對於自己的身體意象較不滿意，其中女性不滿意程度更高。不良的身體意象會帶來許多的影響，可能造成肥胖的惡性循環。過去研究多以居住在美洲等地的亞裔移民者為研究對象，少有針對居住在亞洲的亞裔作調查。因此本研究的目的為探討在不同肥胖程度的成年女性間，呼吸交換率、心率變異性及身體意象等因素是否有差異，同時探討影響肥胖指標（身體質量指數、腰圍、體脂肪百分比）的因素。研究方法：本研究設計採橫斷面式設計，在台北招募符合條件且有意願的女性參與。受試者的納入條件為20至50歲，排除條件為：一、服用影響體重或內分泌的藥物；二、參與研究前3個月內體重變化超過2公斤；三、受試者無法完成評估流程，如：認知問題；四、有精神疾病診斷者；五、懷孕或停經者。評估項目包括：身高、體重、腰圍、體脂肪百分比、呼吸交換率、心率變異性、身體意象（多向度自我身體關係問卷（multi-directional self-body relationship questionnaire, MBSRQ）、圖像評量表（figure rating scale, FRS））、七日回憶活動量問卷（Seven-days Physical Activity Recall, 7-d PAR）、三因子飲食量表-18題版本（Three-Factor Eating Questionnaire, revised 18-item, TFEQ-18）、蒙哥馬利憂鬱量表（Mongomery-Asberg Depression Rating Scale, MADRS）。統計分析使用SPSS第18版（SPSS Inc, Version 18.0. Chicago: SPSS Inc.），採用獨立樣本t檢定（independent sample t-test）、皮爾森卡方檢定（Pearson’s chi-square test）及費雪精確檢定（Fisher’s exact test）檢測不同肥胖程度受試者間的變項是否有差異，並以斯皮爾曼排序相關係數（Spearman rank-order correlation）分析肥胖指標與呼吸交換率、心率變異性、身體意象的相關性。另外，以逐步多元線性迴歸分析（stepwise multiple linear regression）來分析影響肥胖的參數。結果：本研究共納入106位受試者，以身體質量指數24.0公斤/公尺2為切點，分為正常組（57人）和過重/肥胖組（49人），兩組的體重、身體質量指數、腰圍及、體脂肪百分比出生體重均有顯著差異（p < 0.05）。此外，過重/肥胖組的身體意象顯著較正常組差，如自覺實際身形、理想身形、理想與自覺實際身形之差別、多向度自我身體關係問卷總分、“外表評價”、“健康評價”、“身體各部位滿意度”及“體重自我分類”（p < 0.05）。體脂肪百分比與高頻功率（ρ = -0.247）呈顯著負相關，肥胖指標與理想與自覺實際身形之差別（ρ = 0.599~0.693）、多向度自我身體關係問卷總分（ρ = -0.318~-0.423）、“外表評價”（ρ = -0.410~-0.532）、“健康評價”（ρ= -0.289~-0.363）“身體各部位滿意度”（ρ = -0.419~-0.552）、“體重自我分類”（ρ = 0.484~0.611）均有顯著相關（p < 0.05）。多元線性迴歸分析結果顯示，理想與自覺實際身形之差別是三項肥胖指標的影響因素。其他影響因素包括出生體重、生育次數、呼吸交換率及高頻功率。結論：身體意象是影響肥胖指標的重要因素。未來的肥胖防治計畫介入可加入改善身體意象，建立正確的健康體型概念，避免過重或肥胖者盲目追尋不健康的美學，使身體意象更差，陷入肥胖的惡性循環。

Background and purpose: The prevalence of obesity has been increasing for the past decades around the world. In fact, the effectiveness of preventing and treating obesity has always been an important health care issue. Many adjustable and non-adjustable causes of obesity had been proposed, such as an imbalance of eating habits, lack of physical activities, psychological factors and genes. The practice guidelines recommended lifestyle modification interventions, which included diet control along with regular exercise, as the core treatment of obesity. However, the effects were not ideal for different ethnic groups. In order to provide alternative interventions for future weight loss plan, additional studies of risk factors for obesity were required. Previous studies had shown that lower sympathetic activity assessed by heart rate variability (HRV) was related to obesity. In addition, obese men that had higher respiratory exchange rates (RER) were more likely to use carbohydrates as a source of energy, which caused fat to not be effectively consumed and led to an accumulation in the body. Furthermore, other studies also showed that Asians were less satisfied with their body image than other races, and women were more dissatisfied than men. Poor body image could lead to a series of outcomes, such as changes in eating habits, hormonal changes, and depression, eventually forming a vicious circle of obesity. However, little was known about the body image of Taiwanese women. Therefore, the purposes of this study were to (1) investigate the difference of RER, HRV and body image between female adults with and without obesity, and (2) examine the factors associated with obesity indicators. Methods: This was a cross-sectional design study. Women aged between 20 and 50 years old were recruited from Taipei City. Subjects would be excluded if: (1) they were taking medications that affect body weight or endocrine; (2) they had weight fluctuation for more than 2 kg, three months prior to the enrollment of the study; (3) they were unable to complete the questionnaires due to various conditions, such as cognitive problems; (4) they were diagnosed with mental illness; (5) they were pregnant or menopausal. The assessments included: height, body weight, body mass index (BMI), waist circumference (WC), body fat percentage, RER, HRV, body image (multi-directional self-body relationship questionnaire (MBSRQ), figure rating scale (FRS)), physical activity (Seven-days Physical Activity Recall, 7-d PAR), eating behavior (Three-Factor Eating Questionnaire, revised 18-item, TFEQ-18), and depression (Mongomery-Asberg Depression Rating Scale, MADRS). Statistical analysis was performed by using SPSS version 18 (SPSS Inc, Chicago: SPSS Inc.), with statistical significant level set at < 0.05. Independent sample t-test would be used to examine the differences of all measured variables between different degrees of obesity groups. In addition, Spearman rank-order correlation and multiple linear regression analysis were used to analyse whether obesity indicators were significantly associated to RER, HRV and body image. Results: A total of 106 subjects were included in this study, where all subjects were classified into normal group (n = 57) or overweight/obesity group (n = 49) according to BMI. Significant differences were found between two groups in body weight, BMI, WC, body fat percentage (BF%) and birth body weight (p < 0.05). In fact, the body image, which includes the perceived actual body image, ideal body image, difference between ideal and perceived actual body image, total score of the MBSRQ, 'appearance evaluation (AE)', 'health evaluation (HE)', 'body area satisfaction (BAS)' and 'self-classified weight (SCW)' (p < 0.05), of the overweight/obese group were significantly worse than the normal group. BF% correlated significantly with high frequency (HF) in HRV (ρ = -0.247), while all obesity indicators correlated with MBSRQ (ρ = -0.318~-0.423), difference between ideal and perceived actual body image (ρ = 0.599~0.693), “AE” (ρ = -0.410~-0.532), “HE” (ρ = -0.289~-0.363), “BAS” (ρ = -0.419~-0.552) and “SCW” (ρ = 0.567~0.675) (p < 0.05). Multiple linear regression analysis showed that three obesity indicators were greatly coupled with the difference between ideal and perceived actual body image. In addition, birth body weight, frequency of childbirth, RER, and HF were also important factors of obesity. Conclusion: Body image dissatisfaction is an important factor associated with obesity. As a result, body image intervention could be considered in future obesity prevention and treatment by establishing the proper concept of healthy body image. This intervention could also help those who are overweight or obese to avoid pursuing unhealthy aesthetics and over-comparing themselves with other people, in order to prevent them from developing poorer body image, thus falling into a vicious cycle of obesity.