I know that feeling you are describing about almost feeling like you gained it all back. I had a really hungry day last month where I ate way over my calories, I felt an out of control feeling, and almost a panicky feeling, like I KNEW I didn't gain 80+ pounds back, but I still felt like I had derailed my whole plan. It scared me that after several months of being totally in control, I just wasn't there for a few. I was worried that my whole new lifestyle was just a dream and that I was well on my way to my old ways.
The next day I felt back to my new normal, no harm done, and lost a good chunk at my weigh in a few days later! Use it as a learning experience, that a lot of us are never "in the clear" with food, and just need to stay vigilant, and always just go right back to plan!
BTW, a coworker luncheon, especially if you are very hungry, is a binge waiting to happen. It's VERY hard to resist all that food unless you make a firm plan about it ahead of time (and I usually bring my own food to such things). Now you know!
