The question of whether or not you should do cardio on an empty stomach is ultimately decided by your fitness goals. Eating protein, caffeine or nothing at all before a cardio routine will have widely varying effects on your body. Get educated about the results of cardio on an empty stomach -- also referred to as fasted cardio -- to ensure you are doing the right thing for your goals.
If you engage in moderately intense cardio sessions first thing in the morning before eating, you may be able to target stubborn areas of fat more effectively, says Bodybuilding.com. For women, this includes the hips and thighs, which can sometimes be more resistant to giving up their fat stores. Because you have less readily available energy in a fasted state -- meaning not as much glycogen to use for energy -- your body will be forced to dig into those fat stores for energy.
A New Zealand study, published in 2010 in the "Journal of Science and Medicine in Sport," found that both male and female athletes saw improvement in their VO2 max when they performed fasted cardio. VO2 max refers to the amount of oxygen that your body can take in and process. The more oxygen your lungs are able to process, the more effective your body is at processing fat. This means that fasted cardio can be linked to improving your ability to use fat during your workout.
In a 2008 study published by the "Journal of Applied Physiology," cardio training in a fasted state can possibly lead to improvements in your endurance. The study found that participants who did cardio exercise before eating forced their bodies to rise to the challenge of a harsh workout situation and adapt. If you are interested in improving your marathon running, cardio workouts done before eating for the day can improve your endurance and athleticism.
Consuming caffeine before a fasted-cardio session can increase levels of catecholamines in your body, which stimulates fat-burning enzymes to make fatty acids more accessible to burn, according to Bodybuilding.com. If you are going to do fasted cardio, consider drinking a cup of coffee before you start, as the caffeine may help you burn fat. You should also eat before doing high-intensity interval training. HIIT involves including short bursts of vigorous activity into your routine, alternated with periods of less-intense activity to recover. This ramps up your metabolism to burn calories all day. But, if you're hungry, then you won't be able to run, cycle or swim as hard as if you had food energy. If you can't work out as hard, then you won't burn as many calories.
- Bodybuilding: The Best Cardio Tips To Help You Burn Stubborn Fat!
- Bodybuilding: 4 Key Factors for an Empty Stomach Cardio Program
- The New York Times: Really? The Claim: Doing Cardiovascular Exercise on an Empty Stomach Burns More Fat.
- MayoClinic.com: Rev Up Your Workout with Interval Training
- Journal of Applied Physiology: Effect of Training in the Fasted State on Metabolic Responses During Exercise with Carbohydrate Intake
- Journal of Science in Medicine and Sport: Adaptations to Skeletal Muscle with Endurance Exercise Training in the Acutely Fed Versus Overnight-Fasted State