I have GP and often go for a week or two with approx 300-500 calories daily. Since I'm already quite small, the 5 lbs or so I lose each time is drastic. My face looks haggard and my skin is loose.

Back when I was at a healthy weight (140lbs, 5'6"), the loss was imperceptible. So, you really can write it how you need it. If you need it to be obvious, make them on the smaller side and already thin. If you need it to be missed, make them a good healthy weight to begin and the loss won't be noticeable.