RESUMEN
To determine the average weight and height and the prevalence of overweight or obesity and thinness in preschool children of the Southwestern highlands of the Kingdom of Saudi Arabia and compare them with their counterparts living at lower altitudes. A cross-sectional study of 559 preschool children aged 12-71 months born and living permanently at high altitude, and 463 preschool children of comparable age born and living permanently at low altitude. For each child at high and low altitude, age was recorded and weight and height were measured. Weight for height Z-score with WHO standards was used for an assessment of normal weight, overweight or obesity and thinness. The highland preschool children were found to be significantly heavier and taller than their counterparts living at low altitude, 92.1% of all highland preschool children and 67.6% of lowland preschool children were found to have normal weight [p < 0.0001], Overweight or obesity was insignificantly greater among preschool children of the highlands [2.3%] compared to the preschool children of the low lying areas [0.9%] [p<0.7]. Thinness was significantly more prevalent among preschool children of the lowlands [31.5%] than preschool children of the highlands [5.5%] [p< 0.0001]. At both high and low altitude, there were no significant differences in the prevalence of overweight or obesity and thinness between boys and girls. The findings of this study indicate that thinness is a major nutritional problem among lowland preschool children. This may be attributed to the prevailing tropical environmental conditions on the health of children at low altitude