Had you been under a great deal of stress lately? Have U. been struggling with her finances? Job? Relationships? School?
The elevated cortisol causes a cascade effect raising your insulin levels. Insulin will remain effectively elevated in the blood stream for 4-12 hours. Insulin is the primary hormone driving and stimulating weight gain. If you've had 2 or 3 stressful events throughout the day, and you have not had the opportunity to burn off these stress response hormones, your body will store and/or continue to gain weight throughout the entire day.
How do you prevent this from happening? A simple 15-20 minute walk is enough to decrease the stress hormone surge that occurs from a "fight or flight" response. Any regular exercise program will decrease these stress hormones. Adequate sleep also decreases these hormones.
So, if your job is stressful, incorporating an exercise program as simple as a daily walk for 15-20 minutes will notably improve your waistline.