This paper proposes a distributed multi-agent based framework organized on three-layer fog computing architecture for effective optimal economic dispatch in the microgrids. This framework tracks load changes at any time of the day considering sudden entries and exits of the units. To this end, the attendance of the various renewable energy sources including photovoltaics (PVs), wind turbines (WTs), micro turbines (MT) and fuel cells (FCs) is taken into account. The optimization algorithm used in this model is a fast consensus- based algorithm modified by a fuzzy adaptive leader method applicable by taking advantage of fog computing. Lastly, the performance of the framework is examined on a six-bus microgrid. The simulation results show the fast convergence rate and capability of the method to track the load changes with real- time interactions.