You may have heard from personal trainers and fitness magazines that "fasted cardio" helps you lose fat
The theory is that doing fasted cardio at a low intensity in the morning (after an overnight fast) means that you'll be exercise in your "fat burning zone", and as a result you'll be "burning fat".
If you've been a follower if this page for a while, you would know that I'm not a fan of "fasted cardio" for fat loss. The reason is that the vast majority of studies have demonstrated that high intensity interval training (HIIT) is far superior to "low intensity cardio" for overall fat loss.
Low intensity cardio will burn more fat "during" the workout when compared to HIIT (only because for "fasted cardio" to work, you need to spend at least an hour exercising, compared to 20-30min for HIIT).
But HIIT results in much higher fat burning in the 24 hours AFTER the workout, so you end up burning more fat over the course of the day (while fat burning almost completely stops after you finish your "low intensity cardio" session.
HOWEVER: there is hack you can use to get the best of both worlds!
A new study (link below) compared the effects of 3 different scenarios on fat burning after a "fasted low intensity cardio session".
- Eating "nothing" before the cardio session.
- Eating 25g (100Kcal) of protein before the cardio session.
- Eating 25g (100Kcal) of carbs before the cardio session.
What they discovered is this:
- Compared to "Eating Nothing", Eating Carbs before the session resulted in LOWER "Resting Energy Expenditure" (REE), the amount of calories you're burning in the hours AFTER your workout.
- Compared to "Eating Carbs", Eating Protein before the session resulted in almost DOUBLE "Resting Energy Expenditure" (REE). Compared to "Eating Nothing", Eating Protein resulted in 70% higher REE.
Bottom line: if you want to boost the fat burning effects of your "Fasted cardio workout", have 25g of pure protein prior to the workout. This can be done by taking 25g of whey protein, or 12g of full spectrum amino acids (which would be my preference).