BACKGROUND The rapid physical growth and development in adolescence are associated with increased nutritional needs and this depends on the dietary pattern and eating habits of the adolescents. Adolescence is also a period of increased vulnerability to obesity which is not only linked to food intake but also due to a lack of physical activity in the growing years. Dietary habits that are established during adolescence are often sustained till adulthood. Hence the purpose of the study was to understand the prevalence of unhealthy dietary practices among adolescents that could enable schools to create a health-promoting culture by teaching healthy food choices and creating awareness of the ill effects of unhealthy dietary practices. METHODS A cross-sectional study was conducted using a semi-structured questionnaire among adolescents in the age group 15 to 17 years in a panchayat in Kerala. The socio-demographic characteristics, the family details and dietary practices were recorded, height and weight were measured, and BMI was calculated and ELIZ health pathway for adolescents (EPHA) was used for categorising the study participants. A diet score was also calculated to estimate the prevalence of unhealthy dietary practices among adolescents. RESULTS The prevalence of inadequate consumption of fruits was 60.9 % and inadequate consumption of vegetables was 36.9 %. Based on the dietary score, 36.7 % had poor dietary habits and 36.6 % had good dietary habits. A significant association was found between the type of school, occupation of mother, educational status of parents, type of family and inadequate consumption of fruits and vegetables. CONCLUSIONS An unhealthy lifestyle does not just appear in adulthood, it stems from practices children develop during their childhood and adolescence. Awareness regarding the risk factors of non-communicable diseases should be provided to children to enable primordial and primary prevention as powerful tools to prevent these diseases in future.