Like you, I've read a lot of different stuff on the subject. Much of it is anecdotal, leaving me to think that what works for your body is the best choice for you. Medically/scientifically, you will not damage your muscles by exercising on a fasting day. It would take a lot more severe/longer term calorie deficit to deteriorate muscle - as long as you are eating enough protein on your non-fasting days.
Some of the 'facts' that seem consistent despite the source are things like:
You will get best performance, as Creaky Pete says, when you are well hydrated with full glycogen reserves, for something like a race or trying to see what your 'maximum' is. But you will definitely 'train' your body to burn fat-instead-of-glycogen if you do some of your workouts in a fasting state. Both the glycogen-burning and the fat-burning states of metabolism are important in long-distance races and so on.
Muscle-building is a little different. Heavier lifting in shorter/more intense sets with plenty of protein before and after seems to be the accepted wisdom. 'Plenty' of protein isn't as much as we tend to think. Not more than 2gm protein per kg of your body weight as a rough guideline.
Those of us who suffer greatly when we exercise in a fasting state have problems because our glycogen and fat burning mechanisms are still a bit inefficient. I have found over time that it has become easier and easier to exercise in a fasting state. My endurance is slowly increasing and my recovery/feeling of well-being afterward is improving as well. But it's definitely something that ought to be worked on slowly and carefully.
Some of the 'facts' that seem consistent despite the source are things like:
You will get best performance, as Creaky Pete says, when you are well hydrated with full glycogen reserves, for something like a race or trying to see what your 'maximum' is. But you will definitely 'train' your body to burn fat-instead-of-glycogen if you do some of your workouts in a fasting state. Both the glycogen-burning and the fat-burning states of metabolism are important in long-distance races and so on.
Muscle-building is a little different. Heavier lifting in shorter/more intense sets with plenty of protein before and after seems to be the accepted wisdom. 'Plenty' of protein isn't as much as we tend to think. Not more than 2gm protein per kg of your body weight as a rough guideline.
Those of us who suffer greatly when we exercise in a fasting state have problems because our glycogen and fat burning mechanisms are still a bit inefficient. I have found over time that it has become easier and easier to exercise in a fasting state. My endurance is slowly increasing and my recovery/feeling of well-being afterward is improving as well. But it's definitely something that ought to be worked on slowly and carefully.
