What is fasted cardio?
The idea of ​​fasted cardio is to perform a cardio workout without having a meal or snack first. Most of the time, fasted cardio occurs in the morning with a "fast" of 6-10 hours. Here is the evidence for and against fasted cardio, which will allow you to decide if it's a strategy worth trying.
Why does fasted cardio burn fat?
When you exercise, your body's first fuel choice is carbohydrates: After you eat carbohydrates, your body has glucose (the building blocks of carbohydrates) available in the bloodstream and muscles for energy. Long, intense cardio sessions burn through available glucose and then begin to burn stored energy (muscle glycogen).
Weight loss occurs when you burn more calories than you consume - which is why most of us do cardio. However, targeting fat to burn instead of carbohydrates (the body's preferred energy source) can be tricky.
The theory behind fasted cardio is to work at a less intense level, so when glucose is not readily available, the body instead begins to break down stored fat for energy.1 It can be a difficult balance to get the stored body burned. fat for fuel instead of breaking down stored glycogen or muscle.
What are the benefits?
1. Burn stored energy - fat
Normally, people want to try fasted cardio because they think that working out without eating ahead of time forces the metabolism to adapt. However, the type and intensity of exercise performed also have an impact on how your body chooses to fuel your workouts.
Ideal conditions for fat burning include no recently ingested glucose (no food in the last 4-8 hours) and failure to function at an intensity high enough to damage / break down muscle tissue.2
2. Works with intermittent fasting
Intermittent fasting, or eating only during a short period of time during the day, means that a morning workout would most likely occur during a fasting period.
There are many different types of intermittent fasting and research is being conducted on all of its potential benefits and side effects, fasting cardio would easily fit into many of these plans.
3. Can be done immediately upon awakening
There is no better advantage of fasting cardio than eliminating the time it takes to consider training fuel. Typically, you want to wait about 30 minutes after eating to start your workout, which means that if your goal is a 6am workout, you need to finish your morning meal before 5am.
With fasted cardio, you don't have to wake up earlier to have a pre-workout meal or snack, you don't even have to choke on a protein shake - go straight to your workout and worry about nutrition later.
Fasted Cardio for Fat Loss / Weight Loss
So, does fasting cardio really work for fat and weight loss? As with most bodybuilding and exercise strategies, it depends.
Research supports the idea that the more fat we burn without carbs in our digestive system, it may be difficult to get enough energy for your run, bike, or gym session.1
If you like to push hard or do long bouts of intense cardio exercise, your body probably won't perform as well when it needs to focus on reducing body fat for energy.
If your workout is low to moderate intensity cardio, fasted cardio is a small change to your regular routine. You may still be able to adjust to fasted cardio if you find it difficult to wake up early in the morning. That's because you could even do this type of workout 6 hours after your last meal - between lunch and a late dinner, for example.
Studies have shown that regular fasting training makes your body even more efficient at burning fat for fuel over time.2 Without glucose readily available for energy, your cells are forced to adapt for energy. That they need. This means that fat is used when you train at the right cardio intensity.
