Objective: To evaluate prevalence of overweight and obesity in second-year medical cadets and to determine risk behaviors before and after 6 months studying at Phramongkutklao College of Medicine (PCM).
Material and Method: Data on self-report behavioral questionnaires was collected from 92 medical cadets before and after 6 months studying at PCM in 2008. Body weight, height, waist circumference, blood pressure and body fat were measured according to standard protocols.
Results: Overall, prevalence of overweight and obese medical cadets before studying at PCM was 16.30% and 15.22% according to BMI and 27.17% and 15.22% by percent body fat. After 6 months of study, overall mean of body fat and systolic blood pressure were significantly reduced. For males, the mean of weight, BMI and waist circumference were reduced significantly. In contrast, the mean of body weight and BMI of females were significantly increased. The prevalence of overweight in total participants determined by body fat was significantly reduced from 27.17% to 15.22 %. Determination by BMI, obesity was significantly reduced from 34.29% to 14.29% only in males. Behaviors that were found to be significantly increased (p < 0.001) were regular physical activity, night eating, sugar-sweet beverage consumption, amount and frequency of coffee or tea consumption. Significant decrease in time of watching TV or using a computer, and duration of sleep was also determined.
Conclusion: The present study indicated that overweight, obesity, waist circumference and body fat of medical cadets were decreased after study at PCM which is possibly due to increasing exercise. Nevertheless, behavioral risks for obesity were also increasing, therefore, it might result in increased the prevalence of obesity in the future.

Keywords: Overweight, Obesity, Behaviors, Medical cadets