Volume 90, Issue 3, September (2003), pp. 643-650 © The Author 2003
doi:10.1079/BJN2003940

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Habitual meal frequency in relation to resting and activity-induced energy expenditure in human subjects: the role of fat-free mass

Margriet S. Westerterp-Plantenga¹, Annelies H. C. Goris¹, Erwin P. Meijer¹, Klaas R. Westerterp^1
1Department of Human Biology, University of Maastricht, Maastricht, The Netherlands

 (Received 2 January 2003–Revised 10 April 2003–Accepted 13 May 2003)

Habitual meal frequency was assessed as a possible function of components of energy expenditure (EE) in human subjects. Fifty-six subjects participated (four categories differing in body composition): ten older women (fat-free mass (FFM) 42·0 (sd 6·3) kg, aged 59 (sd 2) years, BMI 27·5 (sd 6·9) kg/m²), fifteen younger women (FFM 45·5 (sd 5·2) kg, aged 34 (sd 10) years, BMI 21·9 (sd 2·3) kg/m²), twelve older men (FFM 56·8 (sd 5·9) kg, aged 62 (sd 4) years, BMI 25·7 (sd 3·3) kg/m²) and nineteen younger men (FFM 63·9 (sd 7·5) kg, aged 23·1 (sd 3·9) years, BMI 22·9 (sd 1·8) kg/m²). Measurements consisted of habitual meal frequency by validated food-intake diaries, physical activity by tri-axial accelerometers and resting EE by a ventilated hood system. Habitual meal frequency was expressed as a function of resting EE (including resting EE as a function of FFM), and of activity-induced EE, using regression analysis. FFM differed according to gender and age categories (P<0·01). Physical activity level was higher in the younger men than in the other categories (P<0·05). No relationship of meal frequency with the variables assessed was observed in subjects with a low FFM (the women). In the subjects with a medium FFM (the older men), meal frequency was positively related to resting EE (r² 0·4, P<0·05), but not to the residuals of resting EE as a function of FFM, and inversely related to activity-induced EE (r² 0·3, P<0·05). Resting EE explained 40 % of the variation in meal frequency; adding activity-induced EE increased this to 60 %. In the subjects with a high FFM (the younger men), meal frequency was inversely related to resting EE (r² 0·8, P<0·0001) and to the residuals of resting EE as a function of FFM (P=0·03), and positively related to activity-induced EE (r² 0·6, P<0·0001). Resting EE explained 85 % of the variation in meal frequency; adding activity-induced EE increased this to 89 %. Habitual meal frequency was a function of components of EE, namely resting EE and activity-induced EE, only in subjects with a medium to high FFM (men). FFM-related differences in these relationships suggest a role of physical activity.

Keywords:
Age, Body composition, Gender, Physical activity, Man

Abbreviations:
EE, energy expenditure, EI, energy intake, FFM, fat-free mass, FM, fat mass, PAL, physical activity level