It is a frustration to be doing everything "right" to lose weight, only to have the needle on the scale not budge, even just a bit, in reflection of your efforts.  This especially holds true if you are taking the time to exercise.  So what could be the problem?  You actually may not be expending as many calories in a day as you think. Recent research suggests that some individuals tend to compensate for the extra energy spent during an exercise session by decreasing their activity in other tasks throughout the rest of the day.  In the June 2010 issue of Medicine & Science in Sports & Exercise, researcher Eirini Manthou and colleagues reported findings that obese and overweight women who fell short of their weight loss goals despite participation in an exercise program were compensating for the intervention by being less active during tasks throughout the day; therefore, their total daily energy expenditure was not great enough to promote fat loss.

The investigators wanted to determine the role that nonexercise physical activity played in helping individuals who were involved in an exercise program to lose weight.  The subjects included 34 previously inactive women who were either overweight or obese.  All subjects participated in an eight week supervised exercise training program that included exercising for 150 minutes per week.  They were randomly assigned to one of two groups: exercising twice per week for 75 minutes per session or exercising for five days per week for 30 minutes per session.  Each participant wore a heart rate monitor and recorded her daily activities in a 24-hour physical activity diary and her energy intake in a food diary the week prior to the exercise intervention and during week 8 of the study.  Body composition of the subjects was determined by leg-to-leg bioelectrical impedance scales.

All subjects completed the 8-week exercise training program.  No significant changes in body fat for the group as a whole occurred, nor were there any significant differences in fat loss between the two exercise groups; however, there were significant individual changes in body fat noted.  Those women who lost body fat were classified as "responders" and those who did not were labeled "nonresponders."  Further examination revealed that the responders total daily energy expenditure was greater than the nonresponders; and, that this difference was the result of changes in physical activity performed outside of the supervised exercise sessions.  This behavioral change accounted for the 13 percent variance noted in fat loss between the responders and nonresponders.

The findings of this study highlight the important role that total daily energy expenditure plays in weight control.  Exercise can help, but if you view it as a license to take it easy the rest of the day, you can be mitigating its role in weight loss.  For weight management, the amount of energy that you expend during your daily tasks is as important as the amount you burn during an exercise session.

Note: Before beginning an exercise program or increasing the intensity level of a current routine, a physician's approval should be obtained, especially for older adults and those at risk for or who currently have chronic health conditions.

Source
Medicine & Science in Sports & Exercise; June 2010; pp. 1221-1228; "Behavioral Compensatory Adjustments to Exercise Training in Overweight Women," Manthou, E. et al.,.