There have been on-going debates whether to do cardio in the morning before breakfast – or to do cardio in the afternoon/night. There have been claims made by people that doing cardio in the morning before breakfast targets the fat storage in your body and maximizes fat loss which is completely false. Here’s why…
When you wake up, your body is in a state of Catabolism (Muscle – wasting) mode, your body is constantly burning fuel throughout the day and even at rest. Cardio after waking up, before breakfast is extremely dangerous as your Cortisol levels are high in the morning and you run into the risk of losing lean body mass really quickly.
If you must do cardio in the morning due to tight schedules and such, I would suggest that you have at least a proper meal or a pre-workout shake, both rich in Carbohydrates and protein to prevent/slow down Muscle Catabolism.
The truth about Fat / Weight Loss
Research has shown time and time again that it is not what kind of fuel that you burn while doing cardio that’s important but rather, the number of total calories you burn and the rise in baseline metabolism you get from that cardio. The key to fat loss is a calorie deficit, the higher your baseline metabolism rate is, the more calories you burn, the more calories you burn, the more weight you will lose.
Whether you lose fats or lean body mass depends solely on your nutrition and training routine. Putting unnecessary stress on your body such as cardio on an empty stomach will definitely slow down the fat loss process and hinder your progress.
Fat Burning Zone, Myth or Fact?
Another misconception is this «Fat Burning» zone where it is only active on an empty stomach or after a workout.
The «Fat Burning» zone simply does not exist, doing cardio will raise your metabolism and burn more calories thus, creating a greater calorie deficit that will result in both «weight / fat» loss depending on your diet and training. Different types of cardio may raise metabolism rate higher and create a greater deficit but the important key point to take note of is to never do any strenuous exercise with an empty stomach.
Any type of good cardio requires quite a bit of Anaerobic Metabolism (Glycolysis to produce ATP). If there is not enough ample glycogen in the cell or Carbohydrates in the bloodstream, the body will oxidize Amino Acids and turn them into Carbohydrates for energy.
This means your body will break down your muscles for energy as it has no other energy sources left.
The average human sleeps for 6 to 8 hours since your metabolism (BMR) is constantly burning calories even when you’re asleep, your body is on the verge of burning your muscles for energy sources as you’ve not eaten anything for 6-8 hours and it has no energy sources left.