A quasi-experimental study design was adopted, with an
intervention group and a control group with pre- and post-tests using
the Chinese versions of the following scales: Weight Efficacy Lifestyle
Scale, Nutritional Self-efficacy Scale, Exercise Self-efficacy Scales,
Psychosocial Functional Domain, Adolescent Lifestyle Questionnaire
and Body Shape Scale. Figure 2 shows the data collection procedure
from the four primary schools in a suburban area of Hong Kong from
which students were recruited and assigned to intervention and control
groups.
Anthropometric measurements included height (m), weight (kg)
and blood pressure (mmHg). Questionnaires were distributed to all
adolescents (N=120) who attended the school in Primary 4-6. There
were 119 questionnaires that were completed and returned, as one
participant dropped out of the intervention group. As a result, 119
(response rate 99.1%) questionnaires were analysed for this study.
Altogether we recruited 119 overweight (BMI ≥ 85th to 94th percentile
of age) and obese adolescents (BMI ≥ 95th percentile of age) studying
in Primary 4-6 and aged 10-13, with BMI at or above the 85th percentile.
They were recruited equally from the four participating primary schools,
with 30 from each school. Thus 59 overweight and obese adolescents
from two of the primary schools were assigned to attend the 6-month
efficacy-enhancing weight loss intervention. The 60 overweight and
obese adolescents in the other two primary schools were assigned as the control group and received a leaflet on weight management. Baseline
measurements including weight, height, body mass index and blood
pressure were collected from eachadolescent. Data were computed with
descriptive statistics, chi-squared and t-test based on their responses to
the scales.