The clinical picture of the malnourished patient consists of loss of body fat and lean body mass resulting in weight loss and impaired vital organ function. Weakness and fatigue are often prominent symptoms arising from affected skeletal muscle in these patients.

Skeletal muscle is intimately involved in the process of body energy metabolism and its regulation. The effect of insufficient nutritional intake on skeletal muscle function and energy metabolism was studied in subjects, with various nutritional states. Involuntary muscle function was assessed in the adductor pollicis muscle after electrical stimulation of the ulnar nerve. Energy metabolites were measured in needle biopsy samples from the quadriceps femoris muscle.

After total starvation, muscle function was found to be altered and indicated a low rate of energy turn-over. In extremely obese patients, muscle function was also changed but indicated a high rate of energy turn-over. Semi-starved surgical patients had normal skeletal muscle function.

In anorexia nervosa patients 3-5 weeks of total patenteral nutrition largely normalized their deranged muscle energy metabolism. In the obese patients energy metabolism was found to be altered, indicated a high metabolic rate. This is probably a physiological adaptation to a high body weight. In semi-starved surgical patients normal contents of energy metabolites were found.

These findings indicate that major changes in the nutritional state, induced alterations in skeletal muscle energy metabolism. Skeletal muscle function was concomitantly altered indicating a relationship between energy metabolism and function in skeletal muscle. In moderately malnourished patients however, skeletal muscle function was normal.