Objective: This cross-sectional study was conducted on the associations between body composition, energy expenditure and caloric intake among 45 Nigerian breast cancer patients.

Methods: Forty-five Nigerian breast cancer patients were measured and analysed for their body composition, energy expenditure and caloric intake. Statistical analyses included a chi-square test, Student’s t-test, paired t-test, Spearman correlation and linear regression using Statistical Package for the Social Sciences 23.0.

Results: The body fat indices (body mass index (BMI), fat mass index (FMI), and body fats percentage) show that more than 50% of breast cancer patients were either overweight or obese. The Spearman correlation showed that fat-free mass (FFM) was the most strongly correlated with energy expenditure (r = 0.84). BMI and (FMI – fat mass in relation to height) were significantly correlated with the Harris–Benedict equation for energy expenditure (p < 0.001; p = 0.002), but they were not correlated significantly with the Karnofsky performance status. A paired t-test showed that caloric intake was significantly higher than total energy expenditure (p < 0.001). FFM was the best predictor of resting energy expenditure (REE).

Conclusion: In conclusion, FFM remains the best predictor of REE. High body mass and high caloric intake indicate the need for support from nutritional programmes.