Obesity and the metabolic response to severe multiple trauma in man

In the obese state profound metabolic disturbances exist and it is not known how this disrupted metabolism in obese subjects (body mass index greater than 30) may change their ability to respond to the superimposed, injury-induced stress. Understanding the mechanisms that modify the metabolic parameters in traumatized obese patients is essential in their nutritional assessment and further treatment. We have investigated in 7 obese and 10 nonobese multiple trauma patients, on a whole-body level, the energy metabolism, protein kinetics, and lipolysis in the early catabolic "flow phase" of severe injury when they were receiving maintenance fluids without calories or nitrogen. Traumatized obese patients mobilized relatively more protein and less fat compared with nonobese subjects. A relative block both in lipolysis and fat oxidation is experienced by injured obese patients that results in a shift to preferential use of proteins and carbohydrates. Reduced endogenous protein synthetic efficiency observed in obese patients implies increased protein recycling. Thus obese patients could not effectively use their most abundant fat fuel sources and have to depend on other fuel sources. The nutritional management of obese trauma victims should therefore be tailored towards provision of enough glucose calories to spare protein.