MH: can one become too thin with fasting?

dear MH

i was also wondering if one can become "too thin" from cleansing and fasting...
i'm normally a very small person -- before i got sick i was 100lb and 5 4... i have very small bones, so i didn't need much flesh to cover them, and still looked within "normal".... but i didn'thave much room for error either..

since getting sick, however, i've dropped like 5 pounds... and have not been able to gain anything back... and each time i do a cleanse or some kind of a fast, i start flirting dangerously with the low 90's :( and my BMI becomes totally in the "anorexic" territory, not that BMIs mean anythign much :(

so i was hoping that u might be able to reassure me on this subject....
when u do your 40 day oj fast, does your bmi become totally off the charts too...?

thank you,
wabbitte