Sustainability in food supply chains is desired for production, logistics, and waste management. However, food supply chains have complex systems that differ from other supply chains (SCs). Managing such complexities is challenging for small and medium-sized enterprises due to their heightened constraints, such as infrastructure shortages, high technology costs, limited resources, and inadequate awareness. SC designs need to be adapted to navigate the challenges. The main objective of this research was to identify the practices influencing sustainable supply chain designs in a developing country and create a simulation model to illustrate the potential benefits and challenges of promoting sustainability. Mixed-methods research was utilised, employing a literature review, participant interviews, observations, and survey data to gain insight into the problem, establish objectives, and develop a simulation model complemented by design science research.