February 28 - 29, 2008 Advisory Committee Meeting
Energy Balance Summary
Edward Howley, Ph.D., led follow-up discussion surrounding
In rating the evidence the data suggests that aerobic physical
activity has a favorable effect on weight maintenance and is supported by Type
1, strong, consistent data. There is also a favorable effect of resistance
activities on weight maintenance supported by Type 2, moderate, reasonably
consistent evidence. The beneficial effects of physical activity alone on weight
loss in which there is at least a 5% decrease in weight is supported by Type 1,
strong, consistent data. The effects of physical activity on weight regain after
weight loss is not supported by consistent data in observational studies;
however, 5 RCTs supports the benefits with the data consisting of Type 2,
moderate to reasonably consistent material. In analyzing physical activity and
abdominal obesity, the benefits of aerobic activity is supported by Type 1 and
Type 2, moderate to strong and reasonably consistent data. However, the benefits
of resistance training on abdominal obesity are only supported by a small number
of RCTs and are Type 3, weak and inconsistent data. The data on the effect of
age and gender on physical activity recommendations on energy balance is
supported by both Type 1 and Type 3 data that is weak and inconsistent. The
effect of race, ethnicity and SES has no evidence to support recommendations and
consists of Type 2, 3, and 4 data that are weak and inconsistent.
General discussion in this area included the challenge of
defining weight gain as well as identifying the number of minutes required to
prevent excessive weight gain. One method to deal with this challenge may be to
specify a range of numbers.
In reviewing the studies the type of studies may be more
important then the actual number. There may also be a need for a disclaimer
regarding the issue that women may need to expend more energy. Overall, the
committee should be careful on how the studies are being interpreted.
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