Our GSD (also extremely intelligent breed) has never eaten well when he left her. Whether being boarded at a kennel (familiar kennel) or whether we have left her home with a pet sitter (in the house, staying, not just dropping in). She is rather picky to begin with, but will go days without eating when we are gone on vacations or traveling and she is left behind.
Eventually, she does eat some. Typically, throughout her life, she would lose up to 5 lbs during a week trip. (she's almost 14 years old now) These days, the longest we have left her with a pet sitter is about 3-4 days, and we no longer board her at all.
The only time she has truly refused to eat for any *significant* period of time, was after battling "old dog syndrome" (vestibular syndrome, where something in their inner ear shifts and they are dizzy and vomit, can't walk due to dizziness, etc. Eventually, it resolves, and some are left with a permanent head tilt.) She refused every food offered (from deli meats, to rotisserie chicken, to raw steak) for about a week, even after she had begun recovering and was able to stand without falling over. It took some cajoling, but eventually, she did eat a nibble, and that seemed to re-activitate her hunger pains, which seemed to have turned off during her illness. she had NO food desire whatsoever... until she managed to eat a bite of stir fry steak. Then an hour later she was willing to eat a handful of raw steak and she was done. Then, slowly, she began to have more interest and ate more.
I don't think your dog will purposefully starve. She's just making a statement.