Matthew 6:16-18 (KJV)
16 Moreover when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward. 17 But thou, when thou fastest, anoint thine head, and wash thy face; 18 That thou appear not unto men to fast, but unto thy Father which is in secret: and thy Father, which seeth in secret, shall reward thee openly.
In Matthew Christ teaches that you should not appear to people as fasting, but this should be done in secret. Does this text also cover not disclosing to those who will query one about his/her fasting status?