Dietary intake and resting energy expenditure in relation to weight loss in unselected cancer patients

Weight loss and anorexia are frequent findings in advanced cancer. The progressive wasting could be attributed to changes in dietary intake and/or energy expenditure mediated by metabolic alterations. In this study, we analyzed dietary intake in generalized malignant disease of solid tumor type in relation to resting energy expenditure (REE) and reported weight loss. In a group of 297 unselected cancer patients from a university hospital outpatient clinic, dietary intake of energy and macronutrients from a 4-day food record, REE by indirect calorimetry, height, weight and weight loss were recorded. Protein intake was validated against 24 hr urine nitrogen in a subgroup (n = 53), and no indication of systematic misreporting was found. Mean daily dietary intake was below maintenance requirements, 26 +/- 10 kcal/kg. Weight loss of more than 10% was present in 43% of patients and elevated REE (>110% of predicted) in 48%. Dietary intake did not differ between normo- and hypermetabolic patients, nor was tumour type or gender related to energy and protein intake. Weight loss could not be accounted for by diminished dietary intake since energy intake in absolute amounts was not different and intake per kilogram body weight was higher in weight-losing patients compared to weight-stable patients. Dietary macronutrient composition did not differ from the general population. Dietary intake of energy and protein was decreased, but dietary macronutrient composition did not appear to be changed. Weight loss and hypermetabolism were frequent and not compensated for by an increase in spontaneous food intake. Our results indicate that an expected up-regulation of dietary intake in response to elevated energy expenditure is frequently lost in cancer patients. This may be the explanation behind cancer cachexia rather than a primary decrease in appetite.