The present invention provides a method of preparing an orange peel fermentation product, an orange peel fermentation product obtained therefrom, and uses therefor for manufacture of composition for reducing fat, improving sleep disturbance, and lowering risk of cancers. The orange peel fermentation product not only assists slimming through multiple mechanisms including reducing fat content and increasing triacylglycerol lysis in adipocytes, and enhancing expression of genes associated with lipid metabolism, but also reduces sleep disturbance by achieving normal control of circadian rhythms and lowering risk of cancers by suppressing expression of cancer risk genes.本發明提供一種橘皮發酵物的製備方法、一種由該製備方法製得之橘皮發酵物、及一種橘皮發酵物用於製備減少脂肪累積、改善睡眠障礙、及降低癌症發生風險之組合物之用途。該橘皮發酵物不僅能透過減少脂肪細胞的脂肪含量、促進脂肪細胞分解三酸甘油脂、以及提升脂肪代謝相關基因之表現等多種機制協助肥胖者瘦身，亦可使晝夜節律控制正常化以改善睡眠障礙，並且抑制癌症風險基因表現以降低癌症發生風險。
