We have gotten this question a lot lately. Specifically as people are increasing the duration and consistency of workouts, looking for any possible edge in losing body fat.
There are two camps as it relates to fasted exercise, and I happen to ride the fence on this topic. For years, I have trained fasted. I workout first thing in the morning, usually at 5:30am or earlier, I am rarely hungry when I wake up. In addition, if I have much more than a small piece of toast, or a rice cake I cramp mid workout, especially if I am doing a cardio session. Before the Country Music Half Marathon two years in a row, and all through my training process I rarely ate more than a half a bagel or a banana with a little Peanut Butter. I have successfully maintained my muscle mass, have not become “skinny fat”, and my performance rarely suffered. Now…do I know how much better I would have performed with loaded glycogen stores from a full breakfast or a night before “carb load”…No, because I have not tried it. But I ran a sub 8 minute mile for 13.1 miles and I refueled only once with a couple orange segments. I was happy with this, and I have never considered myself some physical phenom.
What I am noticing more and more with my clients, especially those who are training for, or engaging in weekend endurance activities have adopted the same practices as elite athletes who are training 3-4 hours a day at very high output levels. GUs, Jellies, Electrolyte tablets have become mainstream. I am just not sure that “weekend warriors” really need to refuel and load up the glycogen tanks like elite competitors on a 90 minute bike ride.
My advice and suggestions are all individualized, of course and I would never make a broad statement that will work for everyone. It is trial and error, where performance output is priority. If you feel like you are hitting the wall, or you feel weak/light headed during a training session, by all means use some simple carbs to refuel the system and avoid “bonking”, but I would urge you to put off this carb load, and see if you really need it! The more you can deplete stored glycogen, the more potential you have to burn fat, and teach your body to shift into fat utilization rather than reloading glycogen and making it readily available as an energy source.
If you are going to train fasted on a consistent basis, what I will strongly urge is that you look into a Branched Chain Amino Acid supplement (BCAAs), that will help to save muscle tissue, aid recovery, delay fatigue and repair muscle once it is broken down through training. Test your body, and test your energy levels. Be smart about the duration of exercise, and when you really need to consider “refueling”. On a 45-60 minute run do you really need to be downing a serving of Electrolyte jellies or can you push through and burn some fat!