Factors Associated With Obesity in Adult Women: Respiratory Exchange Ratio, Heart Rate Variation and Body Image

Overview

The prevalence of obesity all over the world has increased year by year, and how to effectively prevent and treat obesity has become an important health care issue. Many adjustable and nonadjustable causes of obesity have been proposed, such as unbalanced eating habits, lack of physical activity, psychological factors, and genes. The practice guidelines recommended lifestyle modification interventions which include diet control combined with regular exercise as the core treatment for obesity, but the effects on different ethnic groups are not ideal. In order to provide more choices for future weight loss intervention, it would be important to find out more risk factors for obesity. Previous studies have shown that lower sympathetic activity assessed by heart rate variability was related to obesity; obese men have higher respiratory exchange rates which might indicate they are more likely to use carbohydrates as a source of energy, and therefore, fat cannot be effectively consumed and led to an accumulation in the body. Furthermore, previous studies showed that Asians are less satisfied with their body image than other races, and women are more dissatisfied than men. Poor body image will lead to a series of effects, such as changes in eating habits, hormonal changes, depression, etc., eventually forming a vicious circle of obesity. However, most aforementioned Asians in these studies are immigrants living in overseas areas such as the Americas, and cannot fully represent the ethnic groups in Asia. Therefore, the purpose of this study are (1) to investigate the physiological and psychological factors influence obesity in adult women, including respiratory exchange rate, heart rate variability, and body image, and (2) to examine the correlations among these risk factors and different degree of obesity.

Methods: This is a cross-sectional design study. Subjects were recruited from Taipei city. Inclusion criteria are women aged between 20 and 50 years old and have willing to participate to this study. Subjects will be excluded as follows: (1) taking medications that affect weight or hormones; (2) fluctuation of weight exceeds 2 kg within 3 months before the enrolled in study; (3) any condition that causes the subject fail to complete the test paper, such as: cognitive problems; (4) diagnosed with mental illness; (5) pregnancy or menopause. The assessments include: obesity-related indicators (height, weight, waist and hip circumference, percentage of body fat), respiratory exchange ratio, heart rate variability, 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 will be performed by using SPSS version 18 (SPSS Inc, Chicago: SPSS Inc.), and significant level would be set at 0.05. Analysis of variance (ANOVA) will be used to examine the differences of all measured variables among different degrees of obesity groups. In addition, we will use multiple linear regression analysis to examine whether overweight and obesity are significantly related to respiratory exchange rate, heart rate variability and body image.