Does a person start using fat as an energy source after 20 minutes of exercise?
• The main source of energy used during an activity depends on the level of effort, not the time of the effort. At rest, the body primarily uses fat as an energy source. As the level of effort increases, there is a greater reliance on carbohydrates to provide the needed energy. So, an individual does not have to exercise for 20 minutes before using fat as a source of energy. In fact, as you read this, your body is primarily using fat for energy. Besides, it’s ridiculous to think that the body has a timer set to automatically switch to fat for energy at the 20- minute mark!
