Microwaves are designed to efficiently transfer energy to the food they heat up. However, the exact amount of energy that goes into the food can vary depending on various factors, such as the type of food, its composition, and the microwave's efficiency.
Generally, microwaves work by emitting electromagnetic waves, which are absorbed by the food's water molecules. This absorption causes the water molecules to vibrate rapidly, generating heat and effectively heating the food.
While microwaves are designed to minimize energy losses, some energy can still escape from the system. Energy losses can occur due to factors such as heat dissipation in the microwave's components, reflection of microwaves from the food's surface, and inefficient energy transfer to certain types of food.
It's challenging to determine an exact percentage of energy that goes into the food because it depends on various factors and can vary from one microwave model to another. However, microwaves are generally considered to be relatively efficient in terms of energy transfer, especially when compared to other cooking methods like stovetop cooking or conventional ovens.