The real beauty of a good workout is not the mechanical consumption of calories that occurs during the workout itself. It’s that your ability to oxidize fat for fuel is upregulated and enhanced. Your mitochondria become more adept at burning fuel, your muscles become more sensitive to the effect of insulin (thus requiring less of it), and the food you do consume gets partitioned as lean, rather than fat, mass. And, with regular workouts, that ability to oxidize body fat and preferentially store energy substrates stays elevated (or rather normalized).
The problem with insisting on fasted training is exactly what you’re experiencing – lack of energy is common. I recall one of our worker bees here who got really into fasted training and ended up feeling like working out with food in his stomach was a waste. Problem was he often ran out of energy – just like you – for workouts and his workout consistency and progress dropped off a cliff because he didn’t want to train with food in him. It wasn’t until he divested himself from the “fed training = wasted training” mindset that he was able to resume progress and get stronger and fitter.
It’s a tricky balance, because workouts on an empty stomach are effective in their own way, and fat oxidation is generally favored over glycogen oxidation since there’s not as much of the latter to go around, but you have to do the workouts. If you don’t have the energy to do them, you don’t get the benefit. Ironically, I bet if you made sure to fuel up before your workouts for the next month or so, your fat-burning machinery would be humming along enough that you could then do workouts in a fasted state without feeling depleted. Even though I don’t make it a point to work out in a fasted state, I can do it without much of an issue if I have to because my fat burning ability is optimized.
In my experience, the best activities to do in a fasted state are really low level movement type stuff, like walking, hiking, cycling, maybe some yoga or real short, real simple body weight exercise routines. The folks who try to consistently lift heavy, run intervals, or go for distance on an empty stomach every single workout tend to crash and burn in the long run, at least from what I’ve seen and heard (in emails and messages from readers). There are outliers, vocal ones, but you might not be one of them.
In short, eat whatever you have to eat to initiate and complete the workout! Try the fasted training again later when you’ve got more of your ducks in a row.
Read more: http://www.marksdailyapple.com/wheat-germ-agglutinin-leptin-early-allergen-introduction-fasted-training-green-bananas-sunchokes/#ixzz2tdRWg5DE