Energy balance

Uniaxial accelerometers (specifically the Lifecorder) significantly underestimate total energy expenditure (TEE) and physical-activity-related energy expenditure (PAEE) compared to respiratory chamber measurements, primarily due to errors in estimating basal metabolic rate and difficulty in assessing sedentary/low-intensity activities.

Do not rely on uniaxial waist-worn accelerometers (like the Lifecorder) for precise calorie counting. They systematically underestimate your true energy expenditure by about 8%. However, they are highly correlated with actual expenditure, making them useful for tracking relative changes in activity levels or for large-scale epidemiological studies, provided you understand the absolute numbers are likely too low.