Dietary Habits and Metabolic Response in Obese Children Whose Mothers Received an Intervention to Promote Healthy Eating

The aim of this study is evaluate the change in eating behaviors, metabolic condition, and nutritional status measured by anthropometry, in children with obesity who were prescribed a diet to reduce their body weight in the usual nutritional consultation, in comparison to children whose mothers participated in an intervention of six group sessions to acquire healthy dietary habits.

Methods. Design. The Obesity Clinic at Federico Gómez Children's Hospital of Mexico conducted a randomized clinical trial between January 2011 and December 2014 with approval from the hospital's Research, Ethics and Biosecurity Committee. After providing written consent, 177 children with obesity (BMI ≥ 95 pc) of age 5-11 years and their mothers were randomly assigned to participate in the intervention group (IG) or the control group (CG). None of the participating children were receiving pharmacological treatment for obesity, were morbidly obese or were associated with a genetic syndrome. Intervention group mothers (n = 90) attended six weekly group sessions, which were led by nutritionists and lasted 90 minutes.

The key message was that healthy dietary habits and health risks are acquired at home and that opportunities for change can be identified in the processes that surround meal times. It begins with selecting and purchasing food, followed by preparation and consumption behaviors. Mothers were encouraged to participate in the sessions which involved the use of food models, videos, slides, and, in some cases, real food. Upon completing each session, mothers were given printed material to add to a home consultation manual. Children in this group were not prescribed diets to reduce their body weight. Control group mothers and children (n = 87) were given the usual nutritional consultation and were prescribed diets that covered their energy requirements according to their age and sex. Similarly, CG mother/child pairs received information regarding food groups and portion sizes, were trained in the use of the food equivalence system to encourage variation, and were instructed on how to prepare the diet at home. Neither group of children received physical activity programs. Upon concluding consultations and group sessions, mother/child pairs from both groups were asked to return for monthly follow-ups over the next three months.

The assignment to intervention or control groups was made using a block randomization with 8 mother/child pairs in each block to assure equal allocation to groups. One of coworkers not involved in data collection produced a computer-generated randomization list using the Stata 11.0 program. Children were randomized at the end of the baseline examination. Taking experiences from the published studies the sample size calculation was based on to expect differences of at less 20% in eating habits between the mothers/children dyad of the intervention or control groups, to detect differences with significant level of 5% and 80% power; the size of sample required was 72 mother/children pairs per group and to allow for 20% drop-out during the follow-up, the investigators aimed at recruiting 86 mother/children dyad per group.

Measurements at the beginning and end of the study. Anthropometry. The weight, height and waist circumference of children in both groups were measured according to international procedures. Weight was measured on a mechanical scale (Seca model-700, SECA Corp., Hamburg, Germany) with 50 g precision. Height was measured on a stadiometer (SECA model-225, SECA Corp., Hamburg, Germany) 0.1 cm precision. Meanwhile, waist circumference was measured at the end of an exhalation with non-elastic flexible tape (Seca model-200, SECA Corp., Hamburg, Germany) in a standing position at the midpoint between the lower costal border and the iliac crest. Body Mass Index (BMI) and percentile value were calculated using CDC data for reference, children with a BMI ≥ 95 pc were categorized with obesity.

Blood pressure. Blood pressure was measured on children's right arm with a mercury sphygmomanometer (ALPK2, Tokyo, Japan) using a cuff that suited arm length and perimeter and following 2004 National High Blood Pressure Education Program guidelines.

Questionnaires. A questionnaire of socio demographic data was applied to the mothers at baseline. In addition, a survey of family feeding habits at home at baseline and three months was applied, the mother was asked about the child's breakfast habit and bring lunch to consume at school, family feeding habits at the time of sitting at the table (place the salt shaker, sugar and sweetened soft drinks on the table, fill the plate, repeat saucer, force the child to finish the meal, accept the exchange of food to what the child wants), frequency of consumption of food (fried, roasted, fruits and vegetables) and drinks (simple water, sugary drinks prepared at home, natural juice, industrialized juice and soft drinks). The amounts of food consumption were not evaluated. A survey of physical activity and sedentary activities was applied; no physical activity intervention was performed during this study.

Blood sample. 5 mL venous blood samples after 12 h fasting periods were drawn to determine glucose (mg/dL)(hexokinase method Dimension RxL Max, Siemens Euro, DPC, Llanberis, UK), insulin (mIU/mL) (chemiluminescence IMMULITE 1000, Siemens), HDL cholesterol (mg/dl) (enzymatic reaction/catalase, using ADVIA ® 1800 equipment), and triglycerides (mg/dl) (ILAB 300, Instrumentation Laboratory, Barcelona Spain). Participating children's HOMA-IR index was obtained through glucose and insulin data (If xGf/22.5).

Statistical analysis. Central tendency measures were used to describe the study population's baseline characteristics. Student's t-test for independent samples was used to compare continuous variables, such as socio-demographic data, dietary habits, feeding behaviors, and biochemical and anthropometric data. Pearson X2 test was used to compare proportions between groups. Continuous data without normal distribution was managed using logarithmic transformation or square root. Student's t-test for related samples was used to identify differences before and after the intervention in each group or its non-parametric Wilcoxon equivalent. The equal proportions test was used to assess the difference in proportions in dietary habits and behaviors between groups. Statistical significance was considered at P < 0.05. Analyses were carried out with STATA SE v.12.0 (Stata Corp, CollegeStation, TX, USA).