balance through a combination of caloric restriction and physical activity. Physical activity, although very important for the maintenance of weight loss, actually has a smaller impact on actual production of weight loss. In studies looking at the role of physical activity alone or in combination with diet, physical activity is responsible for only a 2 to 4 lbs. weight change. To lose weight, many individuals need help to change their behaviors, by using such techniques as goal-setting, receiving feedback on the changes, self-monitoring or writing down information, stimulus control (changing the environment they live in), and problem solving. Merely educating individuals about how much to eat and how much to exercise is not sufficient.
Olson and Strawderman (2003) surveyed 458 pregnant women and asked about changes in their diet and exercise behaviors during their pregnancy. This prospective cohort study followed women from early pregnancy until two years postpartum. Of these women, 41 percent exceeded the 1990 Institute of Medicine (IOM) recommendations for weight gain. Individuals who reported eating much more food during pregnancy than before had a more than twofold risk of exceeding the weight recommendations, and those who reported less physical activity than before pregnancy had a 1.75 relative risk of exceeding the IOM recommendations.
In the study of Icelandic women by Olafsdottir et al. (2006), 34 percent of the women exceeded the IOM recommendations. One of the strongest predictors of doing so was their self-reported caloric intake; women who exceeded IOM recommendations reported consuming 2,186 calories per day, about 300 calories more per day than those with optimal gestational weight gain. This study also reported that increased intake of sugar and fat was related to increased risk of excessive gestational weight gain.
Several studies found that caloric intake and caloric expenditure are related to postpartum weight retention. In Olson and Strawderman’s data (2003), 25 percent of the women retained 10 lbs. or more. Individuals who reported increasing food intake during the second 6 months had a more than threefold risk of greater weight retention at the end of the year, and those who reported exercising often actually had a decreased risk of high postpartum weight retention. These studies suggest that the key behaviors to focus on both during pregnancy and afterward are eating and physical activity behaviors that have an impact on energy balance.