The answer is both.

Eating bananas properly before fitness can ensure the adequate supply of blood sugar on the one hand, and promote the burning of fat on the other hand. In other words, this is an efficient way to exercise, which can mobilize the sleeping fat in your body and make them burn efficiently, thus achieving the goal of losing weight.

During exercise, the body excretes a lot of sweat, and many minerals in the body are also excreted with sweat, mainly potassium and sodium. The "stock" of sodium in the body is relatively large, and it is easy to supplement sodium from food. However, the content of potassium in the body is relatively small, so we should pay more attention to choosing foods rich in potassium and replenish them in time after fitness. Bananas are the best choice to supplement potassium, because bananas are rich in potassium.