...
training on an empty stomach is bad because your body takes the energy it needs from protein...actually destroying your own muscles...
I've heard that too. But this study seems to refute that idea. Not only does muscle protein increase if you exercise before breakfast, but you transport and burn glucose better too:
...
the fasting group showed increased levels of a muscle protein that is responsible for insulin-stimulated glucose transport in muscle and thus plays a pivotal role in regulation of insulin sensitivity...In other words, working out before breakfast directly combated the two most detrimental effects of eating a high-fat, high-calorie [American] diet. It also helped the men avoid gaining weight...
I'm an older athlete. Glucose intolerance and diabetes are dangers we all confront as women enter menopause, and men begin andropause (testosterone decline). So regulating insulin and glucose suddenly become subjects of interest.
Many doctors recommend
The Zone diet promoted by the biochemist Dr Barry Sears as being on the right track. The biggest change you'll notice if you try to get into Dr Sears' "Zone" will be a sharp reduction in the amount of carbs you're allowed to consume. So get used to a carb-restricted diet as you age: more salads and fish; less pizza and pasta.