You can generally use a bamboo lid bento box for both hot and cold food, although there are a few considerations to keep in mind:

Hot Food: Bamboo lid bento boxes are suitable for holding hot or warm food items, but they may not provide the same level of insulation as containers specifically designed for hot food. While bamboo has natural insulating properties, it may not keep hot food at optimal temperatures for an extended period. If you plan to pack hot food, it's advisable to consume it within a reasonable timeframe to ensure it remains at a safe and enjoyable temperature.

Cold Food: Bamboo lid bento boxes are suitable for storing cold or chilled food items. The bamboo lid helps to maintain the desired temperature to some extent. However, if you require longer-lasting insulation for perishable or highly temperature-sensitive foods, consider using additional cooling packs or insulated lunch bags to help preserve the coldness.

It's important to note that the overall temperature retention of the food in a bamboo lid bento box can also be influenced by factors such as the ambient temperature, duration of storage, and the specific insulation properties of the bento box materials.

If you have specific requirements for maintaining hot or cold temperatures for an extended period, consider using specialized food storage containers designed for thermal insulation.