Why can’t you eat during the exam? And 1 bathroom break

I started my professional exams with a different board and we were allowed small snacks. I didn’t always eat it but I usually brought a banana/ similar in with me, water and real coke. I get that they don’t want someone at the centre with a picnic but a small snack and a ‘nice’ drink get the though. Also sitting from home you only get one bathroom break! That’s a lot of pressure to make sure you don’t need to go a 2nd time.