Many popular foods are prepared by battering and breading a substrate followed by deep-fat frying, also known as immersion frying. However, these foods are high in calories and fat. This has led to research on the reduction of fat absorption during immersion frying. This paper focuses on the use of functional ingredients, usually proteins or non-protein hydrocolloids, which can be incorporated into the batter and/or breading, or applied as a post-breading dip to retard oil absorption. Protein ingredients from both animal and plant sources have been applied as films or in aqueous solutions to battered and breaded foods. Non-protein hydrocolloids such as cellulose derivatives, gums, calcium reactive pectins, and other plant-based flours have also been utilized. Due to the applied nature of the process and the potential economic impact, many of the ingredients and strategies presented here have been culled from the patent literature. This paper also describes three theories of oil absorption into fried foods; the water-replacement mechanism, the cooling-phase effect, and the surfactant theory, and reviews research that reports the impact of oil absorption on the nutritional and textural properties of the battered and breaded foods.