Smita Nambiar

Developing waist-to-height ratio cut-offs to define overweight and obesity in children and adolescents.

OBJECTIVE The waist-to-height ratio (WHtR) assesses abdominal adiposity and has been proposed to be of greater value in predicting obesity-related cardiovascular health risks in children than BMI. The present study aims to develop WHtR cut-offs for overweight and obesity based on the 85th and 95th percentiles for the percentage body fat (%BF) in a cohort of children and adolescents. DESIGN Waist circumference (WC), height, triceps and subscapular skinfolds were used to calculate WHtR and %BF. Correlations between WHtR and %BF and WHtR/mid-abdominal skinfold were made. Receiver-operating characteristic (ROC) curve analysis was used to select WHtR cut-offs to define overweight and obesity. Subjects were grouped by WHtR cut-offs, and mean values for anthropometry, blood lipids and blood pressure (BP) variables were compared. SETTING Australian primary and secondary schools. SUBJECTS A total of 2773 male (M) and female (F) subjects of the 1985 Australian Health and Fitness Survey, aged 8-16 years. RESULTS Correlation coefficients between WHtR and %BF were M: r = 0.73, F: r = 0.60, P < 0.01 and WHtR/mid-abdominal skinfold were M: r = 0.78, F: r = 0.65, P < 0.01. WHtR of 0.46(M) and 0.45(F) best identified subjects with > or = 85th percentile for %BF and 0.48(M) and 0.47(F) identified subjects with > or = 95th percentile for %BF. When comparing the highest WHtR group to the lowest, both sexes had significantly higher means for weight, WC, %BF, TG (male subjects only), systolic BP (female subjects only) and lower means for HDL cholesterol (P < 0.05). CONCLUSIONS WHtR is useful in clinical and population health as it identifies children with higher %BF at greater risk of developing weight-related CVD at an earlier age.

Validating the waist‐height ratio and developing centiles for use amongst children and adolescents

Aim: To assess the statistical validity of the waist‐height ratio (WHtR) as an appropriate method of adjusting waist circumference (WC) for height in children and adolescents.

Use of the waist–height ratio to predict metabolic syndrome in obese children and adolescents

To demonstrate that the waist–height ratio (WHtR) is a simple and effective screening tool that could be used to identify obese children with the metabolic syndrome.

A comparison of two screening methods to determine the validity of 24-h food and drink records in children and adolescents

Background/Objectives:Dietary assessment in humans is hampered by the phenomena of under and overreporting of energy intake, when food records are used to evaluate habitual dietary intake. Different methods to evaluate mis-reporting have been proposed using cut-offs derived from estimates of reported energy intake and basal metabolic rate, or, from predictions of total energy expenditure. This study compares the effect of using two different cut-off approaches to screen food records for validity, completed by a large cohort of Australian children (n=2460), from Grades 1, 5 and 10 (aged 5–17 years).Subjects/Methods:Energy intake was calculated from 24-h food and drink records for each child. These data were screened using the Goldberg and McCrory cut-offs. The effect of using these two cut-offs on the collected dataset was explored by considering the mean and standard deviation of energy intake in each year level before and after the cut-offs were applied.Results:The use of the Goldberg cut-off resulted in 9% of the total cohort being classified as underreporters, with 60% of these subjects being in Grade 10. The McCrory cut-offs revealed that overall, 22% of the total cohort underreported EI. 33.3% of Grade 1 children were classified as overreporters with this value falling to about 20% of Grade 10 children, while 10–15% of Grade 1 children underreported, with this figure rising to about 30% in Grade 10.Conclusions:Both the Goldberg and McCrory approaches have their advantages and disadvantages, and we suggest that consideration should be given to the reason for screening data before a particular approach is used, with recognition that these methods do differ in their aims and outcomes. The McCrory method consistently classified a greater number of children as underreporters.

Development of food lists as a first step to develop a food frequency questionnaire for toddlers in a multi-ethnic population

AIM Toddlerhood is an important stage of growth, thus understanding the food intake of children in this age group is important. In Singapore, there is currently no simple tool, such as Food Frequency Questionnaire (FFQ), to collect dietary information from this ethnically diverse age group. Generating an appropriate food list is a crucial step in the development of a FFQ and this step is not clearly documented in the literature. The purpose of this study is to generate food lists and portion sizes for toddlers from three major ethnic groups in Singapore and document the processes involved in this first stage. METHODS A total of 30 mothers (equal number of Malays, Indians and Chinese) of 11-24-month-old children completed three-day food records and participated in the focus group discussion. The reported food items were then categorised into food groups. RESULTS The food lists varied by ethnic groups with the longest list obtained from Chinese toddlers. There were also other foods that were then classified as common foods for all ethnicities. Commonly used utensils among the three ethnic groups were small-sized bowls, plates, cups and spoons. For portion sizes, these utensils were typically half-filled for the toddlers. CONCLUSIONS As all Singaporeans have access to the same foods, the ethnic-specific food lists generated in this study could be combined into one list. Together with portion sizes, this information can be used for developing a semi-quantitative FFQ.

Exploring the influence of breastfeeding on abdominal adiposity in young children using the waist to height ratio

Aim: The aim of the present study was to investigate the association between the duration of predominant breastfeeding and the waist to height ratio-a validated index of abdominal adiposity. Methods: Waist to height ratio (waist circumference/height, both in centimetres) and body mass index (weight (kg)/height (m)) were collected from 896 children aged 5.00-7.99 years. Mothers of these children reported on early feeding behaviour and indicated their highest level of education attained. The 75th and 95th percentiles were used to define high and very high waist to height ratio. Overweight and obesity defined by body mass index were also included in the analyses. Results: There were a higher proportion of children ≥75th percentile for waist to height ratio among the never breastfed group compared to breastfed children. This was statistically significant only in females (P = 0.002). Females predominantly breastfed for 4-6 months (P = 0.003) and >12 months (P = 0.006) had significantly lower mean waist to height ratio than those never breastfed. A similar pattern emerged with body mass index. Among males, delaying solids for ≥6 months was associated with significant decreases in waist to height ratio and body mass index. Females were six times more likely to have waist to height ratio ≥95th percentile than children predominantly breastfed for 4-6 months. This was statistically significant. Increasing maternal education was related to breastfeeding duration. Conclusion: Prevalence of overweight and high abdominal adiposity was significantly greater among females who were never breastfed. Females who were predominantly breastfed for at least 4-6 months had the lowest mean waist to height ratio and body mass index and also the greatest reduction in the risk of very high waist to height ratios.

Validating the waist circumference to height ratio for use amongst children and adolescents

Background: normal weight obesity (NWO) is defined as an excessive body fat associated with a normal body mass index (BMI<25 kg/m2), but its prevalence in the general population is unknown. Objective: to assess the prevalence of NWO in Switzerland according to different cut points used to define excess body fat. Design: cross-sectional study including 3,213 women and 2,912 men aged 35-75 years. Body fat was assessed by bioimpedance and prevalence of NWO was assessed using four previously published definitions for excess body fat. Results: % body fat increased with age: in men, the values (mean SD) were 20.2 5.4, 23.0 5.4, 26.3 5.2 and 28.2 4.6 for age groups [35 - 44], [45 - 54], [55 - 64] and [65 - 75] years, respectively; the corresponding values for women were 29.9 7.8, 33.1 7.4, 36.7 7.5 and 39.6 6.9. In men, prevalence of NWO was <1% irrespective of the definition used. Conversely, in women, a one to twenty fold difference (from 1.4% to 27.8%) in NWO prevalence was found. The prevalence of NWO increased with age when age-independent cut points were used in women, but not in men. Conclusions: prevalence of NWO is low in the general population and higher in women than in men. The prevalence is highly dependent on the criteria used to define excess body fat, namely in women. The use of gender- and age-specific cut points to define excess body fat is better than fixed or gender-specific only cut points.Background and Aims: normal weight obesity (NWO) has been defined as an excessive body fat (BF) associated with a normal body mass index (BMI). Little is known regarding its prevalence in the general population or which cut-offs for BF should be used. Methods: convenience sample of 1,523 Portuguese adults. BF was measured by validated hand-held bioimpedance. NWO was defined as a BMI 30%, along other published criteria. Results: prevalence of NWO was 10.1% in women and 3.2% in men. In women, prevalence of NWO increased considerably with age, and virtually all women aged over 55 with a BMI<25 kg/m2 were actually considered as NWO. Using gender specific cut-offs for BF (29.1% in men and 37.2% in women) led to moderately lower of NWO in women. Using gender- and age-specific cut-points for %BF considerably decreased the prevalence of NWO in women (0.5 to 2.5% depending on the criterion) but not in men (1.9 to 3.4%). Conclusions: gender- and age- specific or at least gender-specific, instead of single cut-offs for %BF, should be used to characterize and study NWO.