The contradiction of stable body mass despite low reported dietary energy intake in chronic haemodialysis patients.

BACKGROUND Dietary energy intake (DEI) is reported to be below recommended values in a large proportion of stable chronic haemodialysis patients, while energy requirement appears not to be very different from that in healthy subjects. Nevertheless, body mass has often been reported to be stable over time. We hypothesized that underestimation of habitual DEI by self-reporting of food intake could explain the contradiction of a neutral energy balance despite an apparently insufficient DEI. METHODS In a group of 38 adequately dialysed haemodialysis patients the values of self-reported DEI and body mass assessed by anthropometry were analysed over a 40-week study period. In the total group, body mass increased over time at a DEI of 29+/-5 kcal/kg of desirable body weight per day. Self-reported DEI was factored by an estimate of the patient's basal metabolic rate (BMR) to arrive at a DEI/BMR ratio. A total energy expenditure (TEE) of at least 1.27 times the BMR is presumed to be required to maintain body weight over time. A DEI that is lower than this minimum value of TEE in patients with stable body mass over time strongly suggests underreporting of habitual DEI. RESULTS In 61% of the patients the DEI/BMR ratio was below 1.27. In these patients, body weight increased significantly over time, despite a DEI/BMR ratio of only 1.06+/-0.15. Body mass index correlated inversely with total DEI (r=-0.39, P<0.05) and the DEI/BMR ratio (r=-0.60, P<0.001), indicating that self-reported DEI was lowest in overweight patients. CONCLUSIONS These observations suggest that the contradiction of a stable body mass over time despite an apparently insufficient DEI in haemodialysis patients is mainly explained by an underestimation of habitual DEI from self-reported food intake.