Introduction: Habits formed during childhood will have a long term impact on health and wellbeing. Good dietary pattern is essential for building of bones. Infants and children obviously need extra nutrition and proper physical activity and exercise for their growth and development. Objectives: to assess the dietary habits of underweight children and normal weight children. To compare the dietary habits of underweight children and normal weight children. To compare the lifestyle of underweight children and normal weight children. Methodology: quantitative research approach with descriptive comparative research design was adopted to assess the lifestyle of school children. 60 children were selected by non-probability purposive sampling method in Government Higher Secondary School at Kirumampakkam, Puducherry. Results: Life style of both underweight and normal weight children were assessed under two areas, dietary habits and physical activity/exercise. It was noted that normal weight children were having good eating pattern and physical activity when compared to underweight children which was significant at p<0.05 level. Conclusion: Dietary habits of each individual and eating pattern are interlinked. This study results shows that majority of normal weight children followed a good dietary habits and physical activity compared to underweight children. And most of the underweight children had poor dietary habits and physical activity. It is highly essential that the under five children should be identified and proper awareness regarding dietary habits and physical habits should be imparted at the earliest.