Objective: To evaluate whether energy intake of nondialyzed chronic kidney disease (CKD) patients is underestimated. Design: Cross-sectional study. Setting: Outpatient clinic of the Federal University of Sao Paulo, Oswaldo Ramos Foundation. Patients: One hundred and thirty-one nondialyzed CKD patients (86 male, 66%; body mass index [BMI] 26 +/- 4.21, mean +/- standard deviation) were included. Body weight change was evaluated after 6 to 12 months in 59 patients of the entire group. Methods: Energy intake was evaluated using 4-day food diaries (3 weekdays and 1 weekend day), and resting energy expenditure (REE) was measured by indirect calorimetry. The ratio of energy intake to REE (EI/REE) was used to evaluate the accuracy of the recorded energy intake. An EI/REE ratio below 1.27 was used to identify patients who were underreporting their current energy intake. Results: The majority of the patients reported an energy intake substantially below the recommendation (22.4 +/- 7.15 kcal/kg/d) and had an EI/REE ratio lower than 1.27. In patients with a BMI greater than or equal to 25, the mean EI/REE ratio was significantly lower than that of patients with a BMI < 25 (1.01 +/- 0.28 versus 1.27 +/- 0.42, P < .01, respectively). In addition, only in the group with higher BMI was the mean ratio indicative of underreporting. When the body weight of a subgroup of patients (n = 59) was evaluated after 7.9 +/- 2.4 months, it was observed that the subgroup of patients who maintained or gained body weight had a mean EI/REE not compatible with this condition (1.13 +/- 0.38). The low ratio, despite increasing or maintaining body weight, is highly suggestive of underreported energy intake. Conclusion: Energy intake of nondialyzed CKD patients seemed to be underestimated and was more pronounced in overweight and obese patients. (C) 2005 by the National Kidney Foundation, Inc.