This concept is flawed, said sports dietitian Kejendran Mangaikarasu of National University Hospital (NUH) and NUH Sports Centre.
Different factors, such as the type and intensity of exercise, affects our bodies’ source of energy.
During low- to moderate-intensity exercise, such as walking or cycling, our body tends to use up more fat stores.
But for high-intensity activity like running or vigorous swimming, our body uses less fat and more of its carbohydrate stores.
The time of the last meal prior to the workout, and the type of food eaten, also matters, he said.
For instance, carbs would slow down the rate of fat being used to provide energy during exercise later.
Eat before you exercise, as the benefits of doing this may outweigh that of exercising on an empty stomach, said Mr Kejendran.
A pre-exercise meal can help you to get the most of your workout.
Text by Mind & Body, Straits Times.