I’m not a nurse, but I’ve noticed the same issue when I work long days while traveling for work. Honestly not sure I have a great answer, just that you’re not alone!
You probably can crush out the entire day though. Would be about a 20 hour fast. Which the first couple times do suck. Maybe try it on a day off first, so you know you have a time you can pull the rip cord if the hunger gets too much? Then if you’ve done it you’ll know you can do it at work as well.