Without caring about his health, he self-indulgently ate large amounts of sweets every day.

self-indulgently 是由 self-indulgent 加副词后缀 -ly 构成的副词。self-indulgent 由 self（自己）和 indulgent（放纵的）组成，indulgent 来自动词 indulge（放纵、沉溺）。self-indulgently 表示"自我放纵地"，形容不顾后果地满足自己的欲望。