The imprecision in prescribing of enteral nutrition in critically ill patients must result in occasions of overfeeding as well as underfeeding. Overfeeding could cause increased CO2 production and thus increased work of breathing and prolonged ventilator dependence. This possibility is supported by the limited relevant literature. We examined this possibility mathematically using the data in The Augmented versus Routine Approach to Giving Energy Trial (TARGET) feasibility study and in its main study protocol. Patients in the energy-dense feeding arm will receive 50% more calories and produce 52% more CO2 than patients in the standard feeding arm. The full TARGET study is ideally positioned to answer the practical clinical question of whether increased feeding in critically ill patients can be delivered without prolonging ventilator dependence.