Congratulations on losing 55 pounds. That is a huge accomplishment!
And congrats on getting the job, too. It's a big adjustment to go back to work. You have less time, and more temptation, and probably more fatigue.
1. Plan to avoid the unhealthy choices at work. Learn what healthy options are available and find ones that you like. Or bring a healthy snack with you.
2. Make sure you get enough sleep. Fatigue makes you crave high fat, high sugar food.
If you are maintaining instead of gaining as you make your transition to work, you are doing great. Give yourself some time to figure it out.