The prevalence of overweight and obesity in children aged
from four to twelve years in Gibraltar

Melanie Mcleod 1 and Sara F.L. Kirk 2

1. Dietetic Department, St. Bernard’s Hospital, Gibraltar and
2. Faculty of Health and Environment, Leeds Metropolitan University,
Calverley Street, Leeds, LS1 3HE.

Introduction
There is evidence to suggest that overweight and obesity in adults is increasing rapidly in both developed and developing countries (WHO, 1997). Data on prevalence of obesity in children and adolescents are more limited. The increasing prevalence of childhood obesity poses a significant problem for authorities to address. The multiple health consequences that arise from childhood obesity are a major concern especially on the health of future generations of adults. Several countries have devised their own growth charts and BMI-for-age charts using their own reference populations. Gibraltar has never devised its own growth charts and currently uses Tanner & Whitehouse charts (Tanner et al.,1976) to monitor growth and define obesity.

Gibraltar is a rocky promontory situated at the southern-most tip of the Iberian Peninsula. A British colony since 1704, it has historically been a garrison of obvious military importance to Great Britain. The numerous sieges laid by the Spanish kingdom during Gibraltar's history resulted in a population consisting of mixed Mediterranean stock (Genoese, Maltese, Portuguese and Jews originally expelled
from Spain during the Spanish Inquisition). With time Gibraltar's civil population, currently approximately 30,000, became even more racially mixed to include British civilians and Spanish nationals, especially women, who came to settle in Gibraltar during the more peaceful periods of the rock's history. As a result, the dietary characteristics of the typical Gibraltarian today is a mixture of Mediterranean and British foods. Clinical experience has demonstrated an affinity to the Mediterranean-style diet of fresh fruit and vegetables, nuts, seeds, fish, olive oil, etc. but the British
influence is also apparent. There are British style pubs in Gibraltar with British beer and typical pub food. British supermarket chains operate in Gibraltar and many of the products available in the UK are also widely marketed in Gibraltar. Fast food outlets are also a growing phenomenon in Gibraltar and this has led to an increase in the
amount of fried food consumed.
This study aimed to determine the prevalence of overweight and obesity in school-age children in Gibraltar. This was the first study of its kind to be undertaken in Gibraltar
and therefore has provided a valuable insight into childhood weight levels for comparison elsewhere.

Subjects and methods
There are 16 schools in Gibraltar. All schools are government run and centrally administered from the Department of Education with the exception of two that are privately run. Population sizes range from approximately 25-900. Only the first, middle and primary schools were included in the study. Pre-schools and nursery schools were excluded because not all children of this age (1-4yrs) in Gibraltar attended them. The two secondary schools were excluded for the same reason. The school attended by children of parents who are posted in Gibraltar working for the Military of Defence was also excluded due to the transient nature of the school population. Children with learning disabilities or who were wheelchair-bound were excluded. There is extensive literature that suggests that disabled children are more
likely to have 'abnormal' weights and heights due to their disability (Rubin et al 1998, Webb, 1980). Pupils who were also absent on the second visit to the school and pupils for whom no date of birth was available were also excluded from the study.

Permission to undertake this study was granted by the Director of Education in Gibraltar. All schools on the island were contacted by letter and informed about the study. Data collection took place over three months from January to April 1998, with absentees measured during May 1998. The same height stand and scales were used throughout the study. Weight was measured using SECA battery operated, self-calibrating scales. The children removed their shoes to be weighed and weight was recorded to the nearest 0.1kg. The height stand was calibrated using a measuring tape to measure a length from the foot platform to the ruler. Children were measured without shoes, their heels together and standing with their heels, buttocks and shoulder blades in contact with the vertical rod. Heights were recorded to the nearest 0.5cm.

Results
Out of a possible total of 3034 children, 2994 were included, a participation rate of 98.7%. Forty children were excluded from the study, either due to absence at the time of data collection, through disability or because of missing data.

Prevalence of obesity and overweight
Approximately 20% of children aged 4-12 years in Gibraltar were obese. A pattern of increasing prevalence of obesity with increasing age in both boys and girls was observed, along with a corresponding decrease in the prevalence of normal weight children. The overall prevalence of obesity was similar for boys and girls. The highest
prevalence of obesity was observed in 11-year-old boys at 33.5%. The highest prevalence of obesity in girls, 29.3%, was also observed at age 11. At age 4 and 5 years the prevalence of obesity in girls was more than twice that in boys. However, because of the small numbers involved, the difference was more apparent than real.

The characteristic pattern of increasing prevalence of obesity with age stopped at age 12 where a decrease in the prevalence of obesity was observed at this age in both girls and boys. The number of obese children was approximately halved in both sexes. However, the number of 12-year-olds in the study was only a sample and does not
reflect the total population of 12-year-olds in Gibraltar. A follow-up study would be very useful in determining prevalence rates for children in the secondary schools to determine whether this decrease continues from 12 to 18 years of age or is just a one-off drop.

Overweight was less prevalent than obesity for both sexes. Overall 14.6% of children aged from 4 to 12 years were overweight. The highest prevalence of 22.7% occurred in 12-year-old boys. Overweight prevalence was generally higher in boys than in girls except for in the 4 and 6-year old age groups. There were no similarities in the patterns for either overweight boys or girls with increasing age as there were for obesity. In girls there was a decreasing prevalence in overweight from 10 to 12 years. The drop between 11 and 12 years may correspond to
the fall in obesity at this age. For boys, however, overweight prevalence reached its peak at age 12.

Conclusions
In conclusion, the prevalence of overweight and obesity in children aged 4 to 12 years in Gibraltar was high in comparison to other countries. Although the reasons for this have not been explored it is hypothesised that a combination of factors has contributes to the development of childhood obesity in this population. More specifically these may include an increase in the consumption of fast foods and convenience foods, a decrease in the adherence to a Mediterranean style diet and an increase in sedentary lifestyles of children and adults. To determine the trends and causes of both adult and childhood obesity in Gibraltar, longitudinal studies are needed together with health and lifestyle surveys. This can only serve to widen the knowledge on this prevalent nutritional disease.