Well, it wasn't the fasting month during BMT for me, but I did
fast while at my unit.
From what I remember they gave tons and tons of food for sahur. I
think they pretty much combined breakfast and lunch for sahur.
Personally, though, I find it extremely difficult to eat so much
solid food at 4am in the morning. A normal breakfast would have
sufficed for me.
Do try your best to fast as much as you can, for I'm sure you don't
want to make up all the days that you missed. At the same time,
though, if you really have to break your fast, then use your own
discretion. It won't do to have you fainting under the hot sun for
lack for food and water.
I personally had to forgo two days of fasting when I was starting
to black out while doing strenous training out in the jungle. I'm
the freakin' company medic, and surely the last thing anyone wants
is for the medic to pengsan. Just be sure to make up for whatever
days you've missed.
Here's a tip: during water parades, instead of drinking the water,
pour it all over your head.