Have you lost weight?
減量してるの?
Have you lost weight?
Have you lost weight?
Were you fat?
Haven't you lost some weight? Are you eating properly?
You've lost some weight, haven't you? Are you eating properly?
Are you trying to lose weight?
まだダイエットしてるの?
You lost weight.
Did you go on any special diets or anything?
You have lost quite a bit of weight.