I would just say something by like… “The last time I ate at (restaurant name) I got really bad food poisoning and had horrible diarrhea for days, so I will pass on eating there tonight thank you…. But I will be doing dinner on my own.”
I would just slide your 8 hour eating window for that particular day (keep carbs low that day to mitigate hunger pangs that might result from the change) so that it overlaps with the work event dinner. Then, the next day move your eating window back to your regular schedule and resume. I’ve done it that way under similar circumstances when I’m doing OMAD or 2MAD which I’m doing currently. I don’t see any downsides to that approach. Working in flexibility is a good way to keep things sustainable.
I always just tell people the truth because I do not like lying if I can help it. I’m intermittent fasting, so I can’t eat past x time. Either that, or if you really do want to eat, you could slide your schedule for one night, but I prefer just being honest. Yeah I’m fat…most Americans are. It’s not a bad thing to try and be healthier, so if people judge you for just trying to be healthier, screw them.
I’d definitely go with the truth and do some internal work to deal with the stares if it happens.
However, my #1 recommendation is actually to just switch your eating window for events. Or not fast and eat something very light whenever you need to break the fast, then hold off until the event and you can have a substantial meal that fits your caloric goals then.
Fasting doesn’t have to be 7 days a week and 100% the same every day. I find that being flexible makes it a lot easier to sustain it in the long term. It also avoids stressing about situations like this.
I go with “I have already eaten and I am not hungry” then proceed to have diet coke or sparkling water.
However, if you want to join them for dinner, moving an eating window (by means of a longer fast or OMAD) is also an option. I found that switching my eating window works well for my body.