Things have changed over the years, but for the last 10 or so, everybody gets BAS.
BAS has two distinct but essentially equal forms:
First is Subsistence In Kind (SIK). This means that they give you food instead of money. Your pay account is credited the same $348.44 as everyone else, and then the fixed daily cost of meals provided is deducted from your pay account on a daily basis. You don't see the money. Since the $348.44 is based on the cost of meals, it is basically a wash. If you don't eat the meal, you get nothing.
Second is Commuted Rations (ComRats). This is where they give you money instead of food. They credit the $348.44 and don't take anything back. You buy your own meals. If you eat at a government facility, you pay for the meals you eat. Again, the cost of meals and your BAS are directly correlated so a meal at the dining hall is only going to cost a couple of bucks.
On a ship you will always get SIK and never get ComRats as your BAS. On a ship, your CO is prohibited from authorizing you to be paid Commuted Rations unless the ship is in extended overhaul and the galley is unavailable. It is very rare to get Sea Pay and Commuted Rations both for the same day.
Normally, married members who live off base are not required to use the dining facility at a shore command. You may have to request this from your command.
Bottom line (intending as I am to answer the OP's question) is that you will get fed every day or you will get paid the cash equivalent of a Navy diet. No more, no less, for every day you are on active duty, including days when you are on leave.
The Navy is required to feed or pay the cost of feeding the servicemember only. So, BAS won't cover the cost of feeding your dependents. If you brownbag pb&j sandwiches every day, you might have a few bucks left to help with the family groceries, but it won't come close to feeding them. If you are depending on BAS to get by, you're cutting too close to the bone.