This study was proposed to investigate the possibility of utilization of some food processing wastes (i.e. whey protein concentrate and orange peels) as a fat replacers in cakes and there effects on the physical, chemical, sensory quality and nutritional characteristics. Results indicated that the use of mentioned fat replacers could  be increase and sensory quality characteristics in low-fat cakes. Butter could be replaced up to70% by whey protein concentrate and orange peels in cakes which were comparable to their full-fat cakes. Additionally some nutritional benefits were achieved as a results of fat replacers such as decreases in fat content and caloric value in all cases, beside the increase in protein content in case of using whey protein concentrate and increased crude fiber in case of use orange peels . Biological evaluation using experimental rats showed significant decrease in total cholesterol, triglyceride, low density lipoprotein (LDL) and liver enzymes (GOT),(GPT) and showed increased in high density lipoprotein (HDL) in rats fed on the fat-replaced cakes. Additionally, such replacement has achieved many nutritional and health benefits when consuming the produced low-fat bakery products.