A method for making a sustained energy beverage comprises mixing together inulin, fruit juices and/or concentrates, and complex carbohydrates from grain dextrins and fruit juice. In a batch method, the mixture is pasteurized, cooled and then stored for use later. A finished beverage is completed by mixing in acids and buffers, and blending. A concentrate is produced that can be sold wholesale, or it can be diluted to 6-22 brix with water. In both the continuous and batch methods, it is pasteurized just before or during bottling to produce a retail sustained energy drink.