Short-term effects of exercise on body water distribution of severely obese subjects as determined by bioelectrical impedance analysis.

We have previously shown that a short-term weight (Wt) reduction programme consisting of energy restriction, physical activity and psychological counselling, produces physiological changes of body water distribution (BWD) in obese subjects as detected by bioelectrical impedance analysis. The present study was aimed at testing the contribution of diet and physical activity to the observed changes in BWD. A number of 96 obese inpatients were consecutively enrolled in the study at our Obesity Clinic. During a 3-wk period, they underwent a body Wt reduction programme comprising the same dietary strategy and psychological counselling. The programme differed as far as physical activity is concerned, with 52 subjects randomized to a baseline exercise programme (BEP), 22 to a cardiovascular exercise programme (CEP) and 22 to a cardiovascular and strength programme (CSP). Absolute and percent Wt reduction was significantly higher in CSP than BEP subjects (p < 0.05) and the same hold for the changes in impedance (Z) at frequencies of 5, 50 and 100 kHz (p < 0.05). The change in the Z5/Z100 ratio did not show however any between-group difference (p = NS). The average values of Z changes were 1.5 to 2 times higher in CEP and 5.0 to 5.5 times higher in CSP than BEP subjects. We conclude that the type of exercise performed does influence the absolute changes of total body water and extracellular water but not BWD in severely obese subjects undergoing Wt loss.