OBJECTIVES: To validate the use of an activity diary and predicted BMR for assessment of daily total energy expenditure (TEE) and physical activity level (PAL = TEE/BMR) in adolescents.

DESIGN: TEE and PAL estimated from activity diary records kept for seven days and BMR predicted from age, gender and body weight were compared with the results of doubly labelled water (DLW) measurements and indirect calorimetry performed during the same time period.

SETTING: The Unit of paediatric Physiology of the Department of Clinical Physiology, University Hospital, Uppsala, Sweden.

SUBJECTS: Fifty randomly selected 15 y old adolescents (25 boys and 25 girls).

RESULTS: The mean difference between TEE estimated in all adolescents by the activity diary and by DLW methods was 1.2%. The limits of agreement (mean difference 2 s.d.) were -3.47 and 3.77 MD/d, equivalent to a coefficient of variation of 15%. The mean difference between PAL assessed by activity diary records and by DLW measurements was 0.001, and the limits of agreement between the two methods were 0.54.

CONCLUSIONS: The results imply that the activity diary method provides a close estimate of TEE and PAL in population groups.