Go the church and select the "Password" option, then activate the following cheats by entering the corresponding codes:

CHEAT FUNCTION - CHEAT CODE
Five loaves of B's-Log Bread - Enter RDNQWEAZ as a password. This item increases the maximum HP.
Five loaves of Famitsu Bread - Enter EQFFGMYP as a password. This item boosts all stats.
Five loaves of Christmas tree bread - Enter UDHJJMRT as a password.
Five Stamina Candies - Enter LQVMFVRR as a password. Note: This item increases the maximum HP.
Rainbow crystal egg - Enter NMKXBWSZ as a password.