In several studies we reviewed, the expected
weight loss (as calculated from the energy
expenditure of the exercise prescribed) was
significantly greater than that which is actually
observed, even when the exercise intervention
was supervised. For example, at the end of the
Midwest Exercise Trial5, women who exercised
were expending approximately 2,200 kcal per
week if exercise was supervised and had increased
24 h energy expenditure by 209 ± 555 kcal
(mean ± SD) over baseline as assessed by doubly
labeled water, yet had lost no weight. Although
energy intake was measured periodically and
not found to be increased, some compensatory
change in calorie intake must have occurred for
body weight to remain stable. This study was,
however, performed at a time of high risk for
weight gain (many participants were college
students) as indicated by the 2.9 kg weight gain
in the control group shown in Table 1.