reply to post by SkepticalSteve
First, get a check up and, hopefully, post what the outcome was. A checkup would include blood workup with smear, thyroid, chemistry and maybe even
hormones and PSA.
Assuming everything is normal, then the next best thing to do is get some accurate readings.
What was your pre-weight and how often do you weigh. Maybe you made a math error. What was your post weight and what is your weight now.
What were you eating late-night? How many calories?
How much activity do you sustain per day, and per week?
Was this weight loss intentional or unintentional? Do you feel you've lost fat weight, or (mostly) muscle weight? Do you feel weak (or strong?).
In essence, more information is needed.
Unless you're actively trying to cut weight and cut water (as in preparing for a wrestling meet), then losing 7lbs/week is very high.
Since a pound of weight/fat is equal to 3500 Kcals, that means you had a 24,500 calorie deficit. Considering that a plain hamburger is about 245-250
calories, that's equivalent to eating 100 less hamburgers per week than usual.
Even total fasting, and wasting syndrome would be unable to sustain a 7lb/week, unless you were going without substantial fluid replacement. (Though
sometimes the first week of the fast up to 15lbs could be lost since most of food is evacuated from the intestines).
Anyway, get back to us with more info and good luck on your checkup.