Should you eat before exercising? Long story short, it depends on your goals and the type of exercising you plan on doing. If your goal is to burn the most amount of fat during exercise then yes, create a program that incorporates fasted, low intensity cardio. However, if your goal is performance or you plan on doing higher intensity exercises like CrossFit, then the science says it’s better to have a balanced meal with an emphasis on carbohydrates a few hours before training (PMID 27609363).
ATP, or more affectionately known as Adenosine Triphosphate, is a molecule within the body that provides cells in the body with energy through the conversion of protein, fats, and carbohydrates. Which macro is used during this conversion depends largely on the type and duration of exercise and energy expenditure. From an energy standpoint, the human body is broken up into 3 different systems: