Systems, techniques and methods for estimating the metabolic state or flux, e.g., the body energy state (“BES”) of a patient, are disclosed. The BES provides a deep insight into the nutritional needs of the patient, thus allowing for a sort of exquisite glycemic control with regard to the patient. The invention discloses systems and methods for estimating fractional gluconeogenesis. The invention also discloses systems and methods for estimating and targeting patient blood lactate concentration, both as a target itself and as an intermediate step to estimating and targeting patient fractional gluconeogenesis glucose production. Nutritional support methods and formulations are also disclosed. The invention is suitable for any sort of patient, including those who are injured, such as with traumatic brain injury, ill, or have other conditions that stress the metabolic system.