I skipped a single meal my first week of IP because I just felt too ill/nauseous to consume anything (from withdrawal symptoms on 2nd day). I still lost 5lbs and a total of 6inches (1% body
This last week (my 2nd week) I accidentally skipped my evening snack because I fell asleep early and hadn't turned on a snack alarm. For my 2nd WI, I lost 4lbs and total of 3.5 more inches.
Definitely stay On Progress and do all your vitamins and meals and veggies - but if you've only skipped one meal, I think you'll be ok (especially since you forced the rest of the IP packet).
I'm still new (starting my 3rd week), but from my understanding, it's just really important not to skip meals because 1. we're already consuming a very low number of calories and 2. we don't want our bodies to think it's going into starvation/mess with our metabolism.