A THESIS Submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa in fulfillment of the requirements for the degree of Doctor of Philosophy,
2014 / Introduction: An increase in the prevalence of eating disorders, body image dissatisfaction, low self-esteem and unhealthy weight control behaviors have been reported among adolescents worldwide, and are a public health concern with physical and psychological consequences. Although underweight and stunting still persists in South Africa, overweight and obesity is increasing in all ages, gender, and ethnic groups. Obesity is a biological risk factor for body dissatisfaction, low self-esteem and eating disorders among adolescents, all of which have been found to be associated with various weight change behaviors and strategies. South Africa being a culturally diverse country is undergoing rapid political, socioeconomic, nutrition and epidemiological transitions, and therefore offers a unique opportunity to investigate this area of research.
Study design: There are two study components: (1) A cross-sectional study to determine gender and ethnic (black and white) differences in eating attitudes, self-esteem and body satisfaction in 13, 15 and 17 year-old boys (n=391) and girls (n=340) living in urban Johannesburg; (2) A longitudinal survey of the Birth-to-Twenty (Bt20) cohort at ages 13 and 17 years (n=1435) to compare eating attitudes, body-esteem and weight control behaviors between black and mixed ancestry adolescents, to examine the changes over time in these variables, and to investigate ethnic differences in the male and female perceptions of female body silhouettes at age 17 years. These ages were selected to provide a diverse sample of adolescents (early, mid and late adolescence).
Methods: Anthropometric measurements were performed on all participants. Overweight and obesity were determined using age-gender specific cut-offs for BMI for children aged up to 17
years. Eating attitudes test-26 (EAT-26) scores were used to determine an increased risk of developing an eating disorder. The total EAT-26 score is the sum of the 26 items and scores range from 0 to 78. Participants who score more than 20 are considered to be at greater risk of developing an eating disorder, and represent more unhealthy attitudes towards food, body weight and eating. Body-esteem was measured using a body esteem scale. It consists of a set of 21 questions which measure 1) global feelings about one’s body e.g. “I like what I see when I look in the mirror”, 2) satisfaction with one’s weight e.g. “I really like what I weigh” and 3) positive evaluations about one’s body and appearance e.g. “People my own age like my looks”. The body-esteem assessment uses a 5-point scale ranging from “never” (1) to “always” (5) and the higher the score the more satisfied the participant is with their body. Total scores are divided into three categories; low body esteem (score 1 to 21), average body-esteem (score 22 to 42), and high body esteem (score > 43). The Rosenberg self-esteem tool was used to measure general self-esteem of the participants. Body image satisfaction tool was used to rate participants satisfaction with different parts of their body whereas, the body esteem scale was used to assess participant’s attitudes and feelings about their body and appearance. A series of randomly placed female silhouettes were used to assess participants association with different attributes. They were also asked to associate a series of randomly placed female silhouettes, with specific words or phrases including clumsy, happy, worst, strong, happiest, best, less respect, more respect, unhappy.
All participants were asked a number of questions about their attempts to change their weight. Girls and boys were asked the following questions: “During the past year have you done anything to try to lose weight?”, “During the past year have you done anything to try to gain muscle?” If participants answered positively they were asked to give reasons, which included;
health and cosmetic reasons e.g. to look better, clothes too tight, too fat, unhappy with self, and want to be a model. They were further asked about the methods they used to lose weight, and their responses were categorized into three groups: (i) healthy weight control behaviors (e.g. to exercise, eat more fruits and vegetables, and to eat less high fat foods and less sweets) [20] unhealthy weight control behaviors (e.g. fasting, eating very little food, skipping meals, cigarette smoking and use of food substitutes (iii) extreme weight control behaviors (e.g. use of diet pills, self-induced vomiting, use of laxatives and diuretics).
Descriptive analyses were completed and stratified according to gender and ethnicity. For normally distributed data we used t-tests and ANOVAs, and for data that was not normally distributed Wilcoxon rank test was done to determine significant difference. Chi-square tests were used to determine differences between categorical data. Pearson correlation test was done to determine linear associations. A p-value of <0.05 was considered statistically significant.
Results: In the non-cohort sample, the prevalence of overweight and obesity was higher in the white girls and boys compared to their black peers, significantly more black than white adolescents of both genders reported an EAT-26 score ≥20 (predisposition to an eating disorder). Although the prevalence of low self-esteem was greater in the white compared to black girls, in the study of the male adolescents, the low self-esteem was more prevalent in the black compared to the white boys. Significantly more black than white girls had high body image dissatisfaction (38.8 vs. 16.7%). There were significant differences between the male and female ethnic groups in their perception of female silhouettes, and the majority of the white girls (65.4%) wanted to be thinner compared to only 38.8% of the black girls. BMI was positively associated with self-
esteem and negatively with dieting behavior in white boys , and with lower EAT-26 bulimic and oral control scores in black boys.
In the Birth to Twenty cohort, black African females had a higher BMI (p<0.001) and an increased risk of developing eating disorders as well as significant increase in the prevalence of weight loss practices between the ages 13 and 17 years. At age 17 years both mixed ancestry adolescents had lower body-esteem compared to black adolescents. The prevalence of possible eating disorders was 11% and 13.1% in early and late adolescents respectively. Males and females shared similar opinions on normal silhouettes being the 'best', 'getting respect' and being the 'happiest', while the obese silhouette was associated with the 'worst' and the 'unhappiest', and the underweight silhouette with the "weakest".
Conclusions: Black African urban teenagers seem to be embracing Western norms to fit in with the demands of Western culture, however there is still evidence of traditional influences in both boys and girls with regard to perceptions of female silhouettes. Our findings suggest ethnicity and gender play a major role in psychosocial disorders. Ethnicity and gender were found to be associated with an increased risk of future eating disorders, as well as weight loss and muscle gain practices. These findings are highly relevant for all African countries undergoing transition, and are important in planning the development of interventions to optimize adolescent health prior to adulthood.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/17460 |
| Date | 20 April 2015 |
| Creators | Gitau, Tabither Muthoni |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf, application/pdf, application/pdf, application/pdf |
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