February 28 - 29, 2008 Advisory Committee Meeting Minutes

Energy Balance Summary

Edward Howley, Ph.D., led follow-up discussion surrounding weight maintenance.

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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