An insulated bag reduces heat exchange between temperature-sensitive items and ambient surroundings. The insulated bag has a bag body which can be covered by a bag lid. The bag lid is provided with a first portion of a securing element. The insulated bag is suitable for insertion into an item space of a mobile delivery robot. The mobile robot has a robot lid provided with a complementary second portion of the securing element. After the insulated bag is inserted into the item space, the two portions of the securing element are connected. Thereafter, when the robot lid is opened, the bag lid is also opened, permitting access to its contents.