Throwing Food

If throwing food is forbidden then why do we throw candies at a Bar Mitzva?

Shalom!

Thank you for your question.

Indeed, one should never throw food, as doing so is considered to be disrespectful. This is especially true if the food will become ruined, unappealing, or otherwise unfit to eat. So too, one may not sit on food, or even on a container containing food, if doing so will squash the food. It is permitted, however, to sit on a container containing food if the food will not be affected by doing so.

Nevertheless, common custom is to throw candies, and in some communities, nuts, at a groom and bar mitzvah boy, because such things are hard or wrapped well and do not become ruined if thrown. Nevertheless, even when throwing food is permitted, one should be sure that the floor is clean. Throwing food at a groom or bar mitzva boy is considered to be acceptable use of food, since throwing such things serves to gladden the one being honored. Indeed, it is even permitted to ruin food if doing so is needed for some type of human benefit. This includes using food for cleaning, as is common with vinegar, lemon juice, and other such things to clean clothing or remove stains. One may also wash one’s hands as is required before eating bread with a beverage, except wine or oil, if water is not available. 

Bread, however, should never be thrown, even if it will not be ruined by doing so though there is a custom in some families to toss the pieces of the challa on Friday night to all those present. The practice is justified by the Ketav Sofer, who explains that the pieces of challa are comparable to the limbs of the offerings in the Beit Hamikdash, which were tossed into the fire on the altar. 

OC 160, 168 and 171 with Mishna Berura