A decrease in physical activity affects appetite, energy, and nutrient balance in lean men feeding ad libitum.
BACKGROUND
It is not clear how decreased activity quantitatively affects energy balance (EB) in subjects feeding ad libitum.


OBJECTIVE
We assessed the effect of an imposed sedentary routine on appetite, energy intake (EI), EB, and nutrient balance in lean men for 7 d.


METHODS
Six men with a mean (+/-SD) age of 23.0 +/- 2.3 y, weight of 69.2 +/- 11.4 kg, and height of 1.76 +/- 0.07 m were each studied twice during a sedentary [1.4 x resting metabolic rate (RMR)] and a moderately active (1.8 x RMR) regimen. During each treatment, they resided in the whole-body indirect calorimeter for the 7 d and had ad libitum access to a medium-fat diet of constant, measurable composition. Meal size, frequency, and composition were continually monitored. Motivation to eat was recorded during waking hours. Subjects were weighed in light clothing each morning, and their weight was corrected to nude.


RESULTS
Energy expenditure was 9.7 and 12.8 MJ/d [P < 0.01; SE of the difference between means (SED) = 0.41] during the sedentary and active regimens, respectively. EI was 13.5 and 14.4 MJ/d (P = 0.463, SED = 1.06), respectively. There was no regimen effect on hunger, appetite, or body weight. By day 7, cumulative EB was 26.3 and 11.1 MJ, respectively.


CONCLUSIONS
Reducing a level of physical activity from 1.8 to 1.4 x RMR can markedly affect EB. A sedentary routine does not induce a compensatory reduction of EI and leads to a significantly positive EB, most of which is stored as fat.
Stubbs
R James
RJ
Biomathematics and Statistics Scotland, Aberdeen, United Kingdom. j.stubbs@rri.sari.ac.uk
Hughes
Darren A
DA
Johnstone
Alexandra M
AM
Horgan
Graham W
GW
King
Neil
N
Blundell
John E
JE
D000328:Adult; D001066:Appetite; D001481:Basal Metabolism; D002153:Calorimetry, Indirect; D004435:Eating; D004734:Energy Metabolism; D015444:Exercise; D006801:Humans; D008297:Male