Although most RCTs show trends towards a
modest improvement in short-term weight loss
with the addition of exercise to diet, this effect
is rarely significant. Again, this result is not
un expected given the low amount of physical
activity generally prescribed. In most of these
studies activity intervention was intended to
expend roughly 1,000–1,500 kcal per week
compared with a caloric deficit of 500–1,000 kcal
per day with the dietary intervention; therefore,
the contribution of physical activity towards
negative energy balance was much less than the
contribution of food restriction. In addition, both
the level of adherence to the activity prescription
and the short duration of these RCTs are
important limitations. To be effective for weight
management, it is likely that excercise needs to be
prescribed and adhered to for longer durations to
improve individuals’ fitness to the point where
they can perform enough work and expend
sufficient energy to cause weight loss.