>There is so much debate on whether training in a fasted state increases fat loss and with good reason – there are a lot of conflicting theories and protocols out there.
Fasting, Cardio and Weight LossThere are so many studies showing that low to moderate intensity cardio in a fasted state (on an empty stomach) increases fat loss, but more recent research just may surprise you.
One study out of the University of Padua, Italy, shows that when moderate levels of endurance exercise are done to lose body fat, fasting before exercise does not enhance lipid utilization; rather, physical activity after a light meal is advisable.
This research was done comparing substrate utilization (the use of carbs, fats and protein for energy) and the respiratory exchange ratio or RER (this is important as this number can dictate how much of a particular substrate is being used) on two separate groups, both performing the same duration and intensity of cardio work. The interesting thing is that while both groups consumed the same diets for a 24-hour period, the tests showed that twelve hours after the training session, VO2 was still higher in those who had breakfast prior to the test and the RER was significantly lower, indicating greater lipid (fat) utilization. This continued on for 24 hours after the exercise. This study shows that eating a small meal prior to a workout created better overall fat loss when performing low intensity cardio work and is contrary to the popular belief that cardio in a fasted state leads to greater fat burning.
I would have to say that the key to fat loss is more of an overall greater caloric expenditure and this comes from resistance training and high intensity metabolic work that revs up your metabolism for many hours after working out. You may burn more calories in the cardio session, but what about afterwards? The key is in keeping your body burning fuel outside of the possible hour you may spend doing light to moderate cardio work. Research not only confirms this particular theory of resistance training with HIIT being key, but if you add a supplement containing caffeine to the mix like you will have a greater amount of fat utilization due to its ability to spare carb/glycogen usage. You will be able to push harder and longer, resulting in an even greater caloric expenditure.
The key to any good fat loss program is not the hour you spend at the gym, but it is what you and your metabolism do for the other 23 hours of the day. If you build some solid fat-burning muscle tissue, you will boost your overall metabolic rate and if you perform short, high intensity workouts, you will not only burn some butter during the actual workout, but you will be burning it for many hours afterwards. Just work hard and eat clean foods from Mother Nature and if you need a helping hand with upping the intensity, try adding some caffeine to the mix before you workout in a fasted or non-fasted state!
Paoli,A., Marcolin,G., Zonin, F., Neri,M., Sivieri,A.,Pacelli,Q.F. “Exercising fasting or fed to enhance fat loss? Influence of food intake on respiratory ratio and excess postexercise oxygen consumption after a bout of endurance training.” Department of Human Anatomy and Physiology, University of Padua, Italy. International Journal of Sport Nutrition and Exercise Metabolism. 2011 Feb; 21(1):48-54.
Antonio, J.,Smith, A.E., Spano, M., et al. International society of sports nutrition position stand: caffeine and performance. Journal of the International Society of Sports Nutrition 2010, 7:5doi:10.1186/1550-2783-7-5.Fasting, Cardio and Weight Loss