Energy expenditure, physical activity and dietary intake among patients with newly diagnosed colorectal cancer.

BACKGROUND: Characterizing energy balance components such as total energy expenditure (TEE), energy intake (EI), and physical activity energy expenditure (PAEE) is crucial to assessing nutritional status and guiding interventions. OBJECTIVE: This observational study explored these variables and their interrelationships in patients with colorectal cancer (CRC). METHODS: In patients with newly diagnosed CRC, PAEE was evaluated as the difference between TEE (doubly labeled water) and resting energy expenditure (REE; indirect calorimetry). Activity monitors worn during the 2-wk doubly labeled water period captured steps/d and time spent in various activity intensities activity. Dietary intake was assessed using a 24-h dietary recall and compared to guidelines and energy expenditure and physical activity outcomes. RESULTS: Twenty patients were included (65% male; age: 56 ± 13 y; body mass index: 28.2 ± 5.0 kg/m). TEE ranged from ∼1500 to 3600 kcal/d and correlated with REE (r = 0.60, P = 0.006) and PAEE (r = 0.56, P = 0.011); REE and PAEE were not correlated. The majority (87.9 ± 6.1%) of time was spent in sedentary behavior, and activity was lower on weekend days compared to weekdays. EI was 2290 ± 29 kcal/d, with only 20% meeting energy and 30% meeting protein intake guidelines. TEE and PAEE were positively associated with EI and negatively associated with protein intake. REE was unrelated to dietary intake, and no associations were found between dietary intake and device-based activity. CONCLUSIONS: TEE and PAEE-but not REE or activity monitor parameters-were associated with dietary intake. These findings emphasize the need for robust, low-burden approaches to assess PAEE to optimize nutrition care in patients with CRC.