I lost about 25 pounds the week I had a baby. I don't think that is the answer you are looking for. I lost about 5-7 pounds when I was sick in the hospital with an infected gall bladder. I don't think that is the answer you are looking for either.
I don't monitor my weight ongoing but I tend to go up and down about 10 lbs either way from my "normal" weight.
Losing weight can be healthy but it also can be unhealthy. It is concerning that American society celebrates all weight loss- no matter how unhealthy. When I lost weight after being sick, I cannot count the amount of compliments I received. We should be trying to be healthy and stay healthy. We should avoid crash diets and other extreme methods to lose weight. If we need to lose weight to stay healthy, we need to change our lifestyle and eat better and increase our physical activity. It is plain and simple. I have read we should only lose 1.5-3 lbs a week.