Underweight, overweight and obesity among South African adolescents: results of the 2002 National Youth Risk Behaviour Survey

OBJECTIVE: The present paper reports the prevalence of underweight, overweight and obesity by gender, ethnicity and grade, among participants in a 2002 national survey among South African school-going youth that included height and weight measurements. DESIGN: A stratified two-stage sample was used. Nationally representative rates of underweight, overweight and obesity were calculated using weighted survey data and compared using chi2 analysis. SETTING: In all, 9224 grade 8 to grade 11 students, present at school in selected classes within selected South African government-funded schools in all nine provinces, participated in this study. Most of the students were between 13 and 19 years of age. RESULTS: Higher rates of underweight were observed for males than females as well as for black and 'coloured' than white students. Within each gender group, black and 'coloured' students had significantly higher rates of underweight than their white counterparts. Higher percentages of females than males were overweight and obese, overall and among black students. Furthermore, white male students had significantly higher rates of overweight than their black and 'coloured' counterparts. Among females, black and white students had significantly higher rates than 'coloured' students. Students in higher grades showed significantly lower rates of underweight and higher rates of overweight. DISCUSSION: These data confirm that South Africa, a developing nation in socio-economic transition, is experiencing both undernutrition and overnutrition. However, these problems are disproportionately distributed by gender, socio-economics and ethnicity. Continued surveillance of nutritional status may be one important component of a national strategy to prevent and control malnutrition.     

Overweight and obesity among Iranian female adolescents in Rasht: more overweight in the lower social group

OBJECTIVE: This study aimed to investigate the frequency of overweight and obesity among Iranian adolescent girls aged 14-17 years and its possible association with maternal education in Rasht city in 2005. DESIGN: A cross-sectional survey on 1054 schoolgirls. SETTING: High schools in Rasht city, Iran. METHODS: A multistage sampling method was used and 1054 randomly selected schoolgirls were studied. Data on age and mother's years of schooling were collected by questionnaire and body weight and height were measured. Overweight and obesity were defined using age- and sex-specific body mass index (BMI) cut-off points proposed by the International Obesity Task Force (IOTF), and compared with 85th and 95th BMI percentile curves of the IOTF reference population, respectively. Data analyses included two groups based on mother's years of schooling: less educated ( < 12 years) and more educated ( > or = 12 years). RESULTS: The overall prevalence of overweight and obesity in this population was 21.9 and 5.3%, respectively. Results of logistic regression analysis showed that the risk of overweight was higher for lower age group (odds ratio = 2.0, 95% confidence interval 0.18-3.09). Overweight was more common in girls with less educated mothers than in girls with more educated mothers (26.0 vs. 19.8%, P = 0.03). CONCLUSION: These data indicate that overweight is highly prevalent among adolescent girls, especially in lower social groups in Rasht, and the rate is exceeding those reported in other parts of the country. Preventive strategies need to be adopted to combat the epidemic of overweight and obesity in this population.     

Both food habit change in the past and obesity status may influence the association between dietary factors and postmenopausal breast cancer

OBJECTIVE: Valid dietary data are essential when trying to identify whether or not one or more dietary exposures are responsible for disease. We examined diet composition in women who reported dietary change in the past compared with non-changers, and how the associations between dietary factors and postmenopausal breast cancer are influenced by dietary change, obesity status and misreporting of energy. DESIGN: A population-based prospective cohort study. Data were obtained by a diet history method, anthropometrical measurements and an extensive lifestyle questionnaire including items on past food habit change. SETTING: The Malm? Diet and Cancer (MDC) study, conducted in Malm?, Sweden. SUBJECTS: A subsample of 12,781 women from the MDC cohort recruited from 1991 to 1996. A total of 428 postmenopausal women were diagnosed with incident breast cancer, during 9.2 years of follow-up. RESULTS: Past food habit changers reported healthier food habits and lower energy intake compared with non-changers, a finding that raises issues regarding possible reporting biases. When excluding diet changers, the trend of increased breast cancer risk across omega-6 fatty acid quintiles was stronger, and a tendency of decreased risk emerged for 'fruit, berries and vegetables'. When excluding individuals with non-adequate reports of energy intake, risk estimates were similar to that of the whole sample. In women with body mass index < 27 kg m- 2, significant trends of increased breast cancer risk were seen for total fat and omega-6 fatty acids, and of decreased risk for 'fruit, berries and vegetables'. CONCLUSIONS: This study indicates that both obesity and self-reported past food habit change may be important confounders of diet-breast cancer relationships. The study demonstrates that sensitivity analysis, through stratification, may facilitate interpretation of risk relationships and study results.     

Risk factors for overweight among Brazilian adolescents of low-income families: a case-control study

OBJECTIVE: To study risk factors for overweight among Brazilian adolescents of low-income families. DESIGN: Case-control study of obese and non-obese adolescents. SETTING: Anthropometric survey including 1420 students (aged 14-19 years) attending a public high school in S?o Paulo, Brazil. METHODS: Selection of 83 overweight (body mass index (BMI) >85th percentile) and 89 non-overweight (BMI >5th percentile and <85th percentile) subjects, frequency-matched by age, gender, pubertal development and socio-economic status. Among the nutritional, familial and behavioural data available, five covariates (parents' obesity, adolescents' past obesity, to have a best friend, dietary restriction and habit of napping) were included in the fitted hierarchical conditional logistic regression models. MEASUREMENTS: Parents or guardians and adolescents were weighed, measured and answered a pre-tested questionnaire applied by trained nutritionists and paediatricians. RESULTS: The prevalence of overweight was 15.2%. As previous risks, obese parents and obesity during infancy presented odds ratios (OR) and 95% confidence intervals (CI) of 2.23 (1.15-4.35) and 3.60 (1.47-8.80), respectively. As concurrent factors, the habit of napping, to have a best friend and reported dietary restriction presented OR (95% CI) of 3.43 (1.32-8.92), 5.15 (1.76-15.07) and 7.26 (2.95-17.88), respectively. Dietary patterns, frequency of obesogenic foods and other physical activity indicators presented no statistical significance. CONCLUSION: In case-control studies, OR may overestimate the true risks. Parents' obesity and previous childhood obesity were identified as risk factors; therefore these factors should be the target for preventive programmes and policies in order to prevent the burden of obesity in the near future.     

Food insecurity among homeless and runaway adolescents

OBJECTIVE: The purpose of this study was to investigate the prevalence of food insecurity and factors related to it among homeless and runaway adolescents. DESIGN: Computer-assisted personal interviews were conducted with homeless and runaway adolescents directly on the streets and in shelters. SETTING: Interviews were conducted in eight Midwest cities: Des Moines, Cedar Rapids, Iowa City, Kansas City, Lincoln, Omaha, St. Louis and Wichita. SUBJECTS: The subjects were 428 (187 males; 241 females) homeless and runaway adolescents aged 16-19 years. Average age of the adolescents was 17.4 (standard deviation 1.05) years. RESULTS: About one-third of the adolescents had experienced food insecurity in the past 30 days. Factors associated with food insecurity were age of adolescent, a history of caretaker neglect and abuse, having ever spent time directly on the street, a small post-runaway social network, and engaging in deviant and non-deviant street food-acquisition strategies. CONCLUSIONS: Based on these findings, our conservative estimate is that nationally more than 165,000 homeless and runaway adolescents experienced food insecurity in the past 30 days. These adolescents are largely hidden from public notice and they are usually missed in studies that address national hunger.     

Pesticide safety training among farmworker adolescents from Starr County, Texas

This study of adolescent farmworkers describes employer compliance with pesticide safety training, a requirement of the EPA-mandated Worker Protection Standard (WPS), and identifies variables associated with having received training within the prior five years. Data are from "A Study of Work Injuries in Farmworker Children, " a three-year cohort study of high school students living along the Texas-Mexico border in Starr County. Data were collected using a web-based, self-administered, confidential survey. Of 324 students who participated in field work between January 1 and September 30, 2003, 68 (21.0%) reported ever receiving pesticide safety training. Overall, the 61 (18.8%) students who reported training within the prior five years also reported that their most recent instruction covered at least three key WPS areas (i.e., entry into a recently treated field, pesticide-related injuries/illnesses, and emergency care for pesticide exposure). Based on a multiple logistic regression, students who were male (OR = 1.97), worked only outside of Texas (OR = 2.73), worked only for commercial growers/owners (OR = 4.35), worked only for contractors (OR = 3.18), worked corn crops (OR = 2.93), and worked potato crops (OR = 3.11) were more likely to report receipt of training within the prior five years. Results suggest that increased enforcement may be needed, especially in Texas, and special educational efforts may be needed to reach female farmworker youth.     

Perceptions of weight and associated factors of adolescents in Jiangsu Province, China

OBJECTIVE: To describe perceptions of weight of adolescents and associated factors. DESIGN: Cross-sectional survey in 2002. SETTING: Eight public middle schools in two distinct socio-economic areas of Jiangsu Province, China. SUBJECTS: Eight hundred and twenty-four adolescents (aged 12-14 years) and 628 of their parents. METHODS: Self-administered questionnaires for students and their parents were used to collect the data. Height and weight of the students were measured. RESULTS: One-third of the girls perceived themselves as overweight, while only 8.9% were actually overweight or obese according to the World Health Organization definition. On the other hand, 15.0% of the girls considered themselves underweight, while 5.6% were underweight according to the definition. Among the boys, one-fifth of those defined as overweight perceived their weight as normal. Furthermore, 23.9% perceived themselves as underweight when in fact only 4.9% were classified as underweight according to the definition. About one-quarter of the students dieted in the past year. Adolescents who perceived themselves to be overweight dieted and skipped breakfast more often. They also had lower intake frequencies of animal foods, Western foods and milk/yoghurt. No disparity was observed in the intake frequency of fruits and vegetables between the groups of different weight perception. Parents' weight norms seemed to favour overweight in both genders, but especially among boys. CONCLUSIONS: Both overweight and underweight concerns were common among girls, while a higher body weight was favoured by normal-weight boys and their parents. Distorted weight perceptions in adolescents, as well as dieting, are problems that need appropriate intervention.     

Gender and occupational health and safety requirements among Saskatchewan farm adolescents

Children on farms perform hazardous work that exposes them to risks for injury. Hazards include operation of heavy machinery, working with limited supervision, working at heights, and performing work prohibited by law in other industries. Incidence rates and patterns of injury are known to differ between boys and girls on farms. Farm adherence to occupational health and safety practices, and whether such practices vary by gender, has received limited study in this occupational setting. The objective of this study was to evaluate associations between gender and work practices, and required occupational health and safety practices, within a sample of adolescent children age 12 to 18 years living on Saskatchewan farms. A cross-sectional study was performed. Measures were obtained by self-report. We compared requirements for boys and girls on the following: (1) use of personal protective equipment (PPE), (2) conduct of specific hazardous jobs, (3) training and supervision for equipment work, and (4) training and supervision for large animal work. A total of 434 children were identified, and 297 (68%) met the eligibility criteria. Of these, 170 were boys (57%) with a mean age of 14.5 years (SD 1.9). Occupational health and safety requirements varied by gender; girls were less likely to be required to use PPE (adjusted OR 2.39; 95% CI: 1.16, 4.94). There was no evidence of an association between gender and the conduct of hazardous work. Gender patterns in required training and supervision for work suggested disadvantages for girls, but were not significant. Adolescent girls and boys both performed hazardous jobs on the farm. Girls were as likely to conduct hazardous jobs but not to be required to use PPE. This gender disparity may indicate a need for a public health approach that recognizes gender as a determinant of work assignment and of health and safety practices on farms.