Objective: The observational study was intended to explore the weight changes and risk factors of weight gain during the self-quarantine and find available methods to lose weight.Method: This was an online retrospective observational study investigating the weight changes before and after home confinement. A total of 530 participants completed the online questionnaire. diet, sleep, self-reported depression, disease history and exercise information possibly relating to weight changes were incorporated into the questionnaire. The differences among four groups (underweight, normal weight, overweight and obesity) in BMI change and weight change were compared, and the risk factors of weight gain was also analyzed by multiple linear regression analysis. Result: Participants were mostly between 21-50 years old, getting an average weight change of 0.82±3.31kg, and an average BMI change of 0.35 [-0.37, 1.00]. 43.77% of them gained weight by 2.99±2.29kg averagely. People with normal weight were easier to gain weight than obese group (p=0.001). There were differences in food intake (p<0.001), eating habits(p<0.001), taste preference (p=0.047), daily exercise step change(p=0.007), exercise (p=0.02) between non-weight gain group and weight gain group. The multiple linear regression revealed that weight gains were associated with sex (p=0.002), food intake (p=0.004), current daily exercise step (p=0.009) and self-reported depression (p=0.002) and weight loss was related to food intake (p=0.004) and pre-BMI (p=0.001).Conclusion: Eating irregularly, increasing food intake, self-reported depression and decreased daily steps were risk factors of weight gain, yet weight loss was related to decreased food intake and pre-BMI.

In this paper, a theoretical algorithm using united Lagrangian-Eulerian method was presented to study the fluid-structure interaction (FSI) problems. This method was used to solve the large deformation of the elastic plate in a continuous cross-flow of ideal fluid. In this approach, material was described by relatively form (e.g., Lagrangian for structures, Eulerian for fluids, Lagrangian and Eulerian for the interfaces of them). The coupling between the fluid and elastic plate domains were kinematic and dynamic conditions at the interface. For the elastic plate in a continuous flow of ideal fluid, the kinematic equation and dynamic equation of fluid-structure contact surfaces were established using united Lagrangian-Eulerian method. The knowledge of the large deformation is given by using the Fourier series expansions method. It is shown that the united Lagrangian -Eulerian method is an effectively method for the problem of elastic plate in an ideal cross-flow.