Abstract : A study to assess the knowledge and attitude on eating regarding prevention of  obesity among college students who attending in  psychiatric hospital at Chennai. The research approach used for this study was quantitative approach. The research design for this study is non experimental descriptive research design . Sample size was 100 college students.  Convenient  sampling technique was used for the study. The collected data was analyzed by using both descriptive & inferential statistics. The study result found that out of 100 samples the majority of students  64 (64 %) had inadequate knowledge, 24    ( 24%) had moderately adequate knowledge and 12 (12%) of students   had inadequate  level of knowledge regarding prevention of obesity. Based on the  attitude on eating majority of students 57 (57%) had poor attitude, 31 (31%) had good attitude, 10 (10%) had very good attitude and 2 (2%) had excellent attitude. The overall knowledge mean score 12.63. The overall attitude mean score 46.2. There was a significant association found between the knowledge and age, education of mother, dietary pattern, hobbies. There was a significant association found between the   attitude and  education of mother, place of living, dietary pattern.  The main conclusion drawn from this study was majority of students had inadequate & moderately adequate   knowledge regarding prevention of obesity and majority of students had poor and good attitude on eating regarding prevention of obesity.