Aims: This study aimed to assess possible alterations in adiposity and dietary intake during holiday periods in healthy subjects.
 Study Design: 452 students of medicine faculty of Mashhad University of Medical Sciences were participated in this study and announced via internet and campus announcement in Feb 2014.
 Methodology: Anthropometric parameters and body composition were measured using standard protocols. Individual nutritional intakes were assessed using the Dietplan6 software. SPSS software version 11.5 was used for statistical analysis. 
 Results: Of the 452 students who attended the pre-holiday visit, 433 returned for the post-holiday appointments. Of these participants, 82 (18.1%) were men. The mean age was 24.4 years for men and 23.8 years for women (p=0.171). All the adiposity and body composition variables significantly changed over the follow-up except for fat free mass (p=0.074) and truck fat free mass (p=0.935). Mean weight of participants increased from 63.5 kg to 63.9 kg at the end of holiday (absolute change 0.37 kg, p<0.001). Total energy intake increased by 16.4%, carbohydrate by 15.9% and total fat by 25.4%, and significant association were observed between changes in some dietary variables and change in adiposity during follow-up (15 days).
 Conclusion: In conclusion, holidays like Nowruz play a significant role in periodical weight gain and obesity in the college students of Mashhad University. Moreover we have found that dietary intake of carbohydrate and total fat increased through Nowruz holiday. Understanding times when people are more likely to gain weight including holidays is important for the development of prevention strategies.