Carbohydrates vs fat as fuel?

Carbohydrates and fats serve as crucial fuel sources for the body, each with distinct roles, especially during exercise.

1. Carbohydrates:

   • They are the body's preferred fuel source during high-intensity exercise because they can be quickly accessed and utilized for energy.
   • Carbohydrates begin their energy contribution anaerobically and finish aerobically in the mitochondria, allowing for immediate energy release, which is essential for intense activities 1.

2. Fats:

   • Fats provide a more sustained and abundant energy source but are metabolized slower than carbohydrates.
   • To utilize fat, the body undertakes a longer process called beta-oxidation, which requires oxygen. This makes fats a primary fuel during lower intensity, longer-duration activities where immediate energy is not critical 2.
   • Importantly, almost all the energy from fat is mobilized systemically (i.e., from all over the body) rather than locally from the exercising muscles, which means accessing this energy source is slower compared to carbohydrates 1.

In practical terms, for short, intense bursts of activity, carbohydrates are more effective. For long-duration, low to moderate intensity activities, fats are more beneficial. However, the ability to efficiently switch between these fuel sources, known as metabolic flexibility, is crucial for optimal performance and health 3.