It depends on a lot of variables so unfortunately it's impossible to give u an accurate answer. It depends on if the person is exercising, how many calories a day they were eating before they developed anorexia, whether they have much muscle or if they're thin but flabby and not toned, etc. 130 for 5ft8 is already very skinny :l
sometimes in the first 2-3 weeks of only eating an apple a day the person can lose 15lbs, but most of it is water weight and the fact that nothing is in your stomach and by then your colon (ew sorry) would have been flushed out & there won't be much waste in there. But although the person could lose up to 15lbs, they will be very bloated, so honestly honestly you wouldn't be able to notice a difference (and I'm telling you from lots of first hand experience!) After 2-3 weeks the person will become bloated all over and everything swells up a bit, making it look asid thy have put on weight.. After about 4 weeks is when you'll start to notice the person looks skinnier, but they will also look unhealthy. Hair goes brittle and dry like straw and falls out, skin goes a yellowy pale colour and gets really dry in some places and really oily in others. Circulation reduces throughout the whole body so arms, legs, everyhinggg goes purpley/blue/white splotches.
Now u can say as much as you want that you're asking out of curiosity, or about a friend, whatever.. But I've been there! 'trying' to become anorexic :p and it's no fun.. You're metabolism really does slow down soo much.. So next time u want a soda, or some chocolate, or even a piece of pizza, expect to put on weight. I'm not gonna tell you to eat properly and exercise and blah blah blah cause I know, that feels like it just takes way too long! So I'm just gonna say, instead of eating 1 apple a day (cause that will shut down your metabolism) eat half an apple for breakfast, some carrot sticks for morning tea, half the apple for lunch, some cucumber for afternoon tea and salad for dinner, even better if u can add some chicken or tuna to it. An apple only has about 50 calories, a whole carrot 30, & some cucumber sticks about 15.. So if u add what u would eat in a day you would still only be having about 120 cals a day, with chicken or tuna in the salad it woul be about 180-240. That's still like nothing! Most anorexics eat about 200 cals. So I definately don't want u 2 be eating that little! But if you're serious about this, atleast b eating more often so it's not completely life damaging and it's easier on your organs.
Don't do it.