Why are primary school children overweight and obese? A cross sectional study undertaken in Kinondoni district, Dar-es-salaam.

Background: The world is experiencing an alarming increase in prevalence of childhood obesity. Despite this trend little is known about determinants of childhood obesity in Tanzania. A cross sectional study determined the prevalence and factors associated with overweight and obesity in 1722 children aged 7-14 years (10.9 ± 1.74) attending primary schools in Dar es Salaam.

Methods: Six public and four private schools were systemically selected from a total of 227 primary schools. Anthropometric measurements (weight and height) were collected using a standard protocol and Body Mass Index (BMI) was calculated. Interviews collected demographic characteristics and lifestyle factors. Multiple logistic regression test was used to assess the influence of independent variables on overweight and obesity while controlling for confounding factors. The level of significance was set at α = 5 %.

Results: Of 1, 722 children 10.2 % were overweight and 4.5 % were obese. Overweight and obesity was higher in boys (14.9 %) than girls (14.5 %), higher in children attending private schools (27.7 %) than public schools (5.9 %). Children who walked to and from school were less likely to be overweight or obese than those who used vehicles (AOR = 0.5; 95%CI: 0.3-0.6; p < 0.001). Those who used private cars or school buses were more likely to be overweight or obese than those who used public transport (AOR = 2.9; 95%CI: 0.2-0.7; p < 0.05). Computer/video game use were associated with increased risk of overweight and obesity (AOR = 1.6; 95%CI: 1.1-2.3; p = 0.03). Lunch provided by schools was associated with increased risk of overweight or obese (AOR = 6.4, 95 % CI = 4.2-9.6, p < 0.001).

Conclusions: The findings of this study identified a number of behavioural and dietary factors that are related to overweight and obesity. Parents and teachers should encourage children to be physically active by limiting screen time and promoting active transport to and from school to promote health and reduce obesity. Ministry of education needs to formulate/enforce policies that encourage physical activities for school children and regulate quality of foods provided to children at schools.