It really does depend on the helper. Ours don't cook (but loves food) and she seems to really appreciate eating what I cook for our family. (She does all the food prep and washing up, so I don't mind doing the actual cooking.)
I asked her if she would prefer a food allowance and offered her HK$1000 with access to all our condiments (she eats quite a lot so I would still spend less thru the money I save from not needing to buy her share) but she told me she still preferred for us to provide food instead. What I do is have her buy additional supplies from the Philippines stores and put it on our household account in order to supplement her breakfast/lunches and on the weekend when my husband and I eat out. (It usually only amounts to about HK$200 a month.)
On a separate note, what does everyone do for their helper's toiletries and other daily-use items (shampoo, toothpaste, soap, body lotion, face cream etc.)? I've been buying them for our helper but my colleagues at work tell me that their helpers buy their own. What's the normal practice?