Question: What happens to my fat when i run?

Sonia Rodriguez answered on 11 Jul 2020:

Hi Jamie! We can think of fat as an energy storage that our body can use when needed.
When we start to run, our muscles use the carbohydrates from the food we eat or stored within the muscles because they are easier to get. If we keep running or doing moderate exercise for longer, then the carbohydrates are not enough and the muscles begin to use the fat reserves to get more energy. This is more difficult for our body and takes more time, because those fats need first to be transformed, then go to the blood and finally be transported to the muscles.
Let’s use some examples. If we are running a 100-meters sprint (that is short and fast) our muscles will be using only carbohydrates. However, when we run a marathon, our muscles use first the easily available carbohydrates and later large amounts of fats.
Doing regular exercise has also positive effects on your fat after you’ve finished. When we do exercise regularly, our muscles send signals to the fat to be prepared for the next exercising session. That way, our fat is more active and ready to send fats to the blood faster.