A new study has compared the fat burning potential of working-out before breakfast to working-out after breakfast and to not exercising at all. It was thought that exercising would result in an increased appetite later in the day to compensate for the energy used, however this was not the case.
All groups consumed similar amounts of food. Furthermore, those who exercised before breakfast burned 20% more fat than those who exercised after breakfast (and they did the same workout!). So why does this happen? To exercise we need energy. If we exercise before breakfast the only energy we have is from stored fat, whereas if we exercise after breakfast, energy is more readily available from food, therefore, little fat burning.
Breakfast is still the most important meal of the day however, and it is not recommended that you skip it as skipping breakfast has been linked with weight gain.