How do you use 식사, 음식, and 밥?
I've heard the following interpretations for two of these words:
밥 = any daily meal, literally rice
음식 = general food and beverage, cuisine, dish (not a literal plate, but a meal like in the English sentence "This was a delicious dish.")

I've not heard a general interpretation other than "food" for 식사. Would you provide some examples of how to properly use all of these?

Question

How do you use 식사, 음식, and 밥?
I've heard the following interpretations for two of these words:
밥 = any daily meal, literally rice
음식 = general food and beverage, cuisine, dish (not a literal plate, but a meal like in the English sentence "This was a delicious dish.")

I've not heard a general interpretation other than "food" for 식사. Would you provide some examples of how to properly use all of these?

Answer

식사 means the action of having a meal (and more rarely for the food itself).   It is a more formal word than 밥 but is still widely used in daily life, usually used as a noun and as 식사하다 (have a meal, dine) when used as a verb.  Note that 식사를 먹다 is not used.  Because 사 means doing something, it doesn't sound right with 먹다.

밥 can mean both the meal itself (usually the traditional bowl of rice) or having a meal.  밥(을) 먹다 corresponds to 식사하다.  밥(을) 하다 means making a meal, not dining.

음식 corresponds to "food" in English.  it can mean any kind of food, and is more general and not used much for a daily meal.  For example, we never say 음식 먹으러 갑시다.  "Let's go have something to eat" would always be 밥 먹으러 갑시다, 아침/점심/저녁 먹으러 갑시다, or 식사하러 갑시다.

Answer

식사 means 'eating work' literally and it was originated from Japanese. So I don't like that word. But Korean people use that word many times. ex) 식사 하셨습니까?(Have you had meals?) 
I like the followings more.
아침 드셨어요?(Have you had breakfast?)
점심 드셨어요?(lunch)
저녁 드셨어요?(dinner)