for some ppl, they get different reactions to foods in the morning before exercising. I suppose it depends on what type of a person you are, and it depends on what you eat. I absolutely cannot have eggs, or bread in the morning before a workout, i just feel eww. But i do like to maybe have an orange, or an apple. I suggest though, not eating a huge meal, since you don't want to be in digestion mode while you're running.
But if u can eat oatmeal, eggwhites n such right before a workout n be fine with it, sure, go ahead.
about the metabolism thing, i heard that what you eat yesterday, effects your metabolism today. I usually have a scoop of whey protein before going to bed.also keep in mind, if the last meal you eat is at 7pm...n u wake up at 6-7am, you havent eaten since 12hrs ago, so, its important to have somethin healthy in the morning.