In situations where one is not returning food to a heat source in keeping with the conditions outlined above (see: Returning Food to a Heat Source, p. 421), it is still permitted to heat food on Shabbat itself under certain conditions, which ensure that one does not violate the prohibited labor of cooking and one does not heat the food in a manner reminiscent to cooking.

First, an important note: Every time it is stated below that it is permitted to place a certain food on a warming tray on Shabbat itself, there is a difference between the practice of Ashkenazim and Sephardim: In the opinion of many Ashkenazic authorities, even when it is permitted to place a food item on a warming tray on Shabbat, it must be placed on top of an object that separates the food from the warming tray, for example, an inverted pot or roasting pan that is on the warming tray, with the food that one wishes to heat placed only on top of it. By contrast, many Sephardic authorities maintain that one may place the dish directly on the warming tray.

A dry food that has already been fully cooked: Dry foods, such as frozen halla (that does not have small pieces of ice on it) or roasted nuts, may be placed on a warming tray on Shabbat in order to defrost and get warm, even if they will get warmer than the temperature known as yad soledet bo (45° C, 113° F). As stated above, according to the ruling accepted by Ashkenazim, one must place them on something such as an inverted tin pan that will interpose between them and the warming tray, whereas according to Sephardim, one may place them directly on the warming tray.

Likewise, any food that is dry and cooked, such as a breaded cutlet or a casserole, even if it is entirely cold, may be placed on a warming tray on Shabbat. Some are stringent not to do so even when the food is fully cooked.

Liquids: Liquid foods that have cooled may not be heated on Shabbat. One also may not put them in a place where they can warm up above the temperature of yad soledet bo. However, according to Ashkenazim, even if they have cooled below the temperature of yad soledet bo, if they are still noticeably warm and would be eaten even though they are not generally eaten cold, then one may heat them up.

According to Sephardim, there is a distinction between a dish that is entirely liquid, such as soup, and a solid dish that contains a small amount of liquid, such as fish cooked in a sauce. In the case of fish, it is permitted to place it on a source of heat and warm it even more than yad soledet bo. The reason is that the dish is considered to be a dry food because the majority of the food is dry, notwithstanding the small amount of liquid.