Along with the rapid development of the trend in the health sector, various studies have been conducted to find alternative healthier foods, one of which is reducing fat consumption. Currently, many researchers focus on one of modified starches that can be utilized as a fat replacer is starch modified with OSA (octenyl succinic anhydride). In the last decade, there have been quite a lot of publications related to OSA starch, further the number is still increasing. This review discusses the synthesis method of OSA starch and its optimization, functional characteristics, and its application to be a fat replacer in many kinds of products daily consumed. Various pre-treatment methods could be applied to create OSA starch which has higher degree of substitution values. The presence of conjugate bonds with the OSA group in starch polymers could produce very amphiphilic starch characteristic so as to have an emulsifying function. Emulsions shaped from OSA starch were utilized as fat replacers in foods with high level of fat content. Partial OSA starch substitution was successfully utilized as a fat replacer for several types of food products with similar sensory attributes or even slightly better than the native product. The resulting product could be defined as a healthier choice because it had relatively lower fat and calorie content. Even so, adjustments through further study are still needed so that the food produced is able to have a higher level of sensory acceptance relative to native food without fat substitution.