[Effects of self-selection of dietary sessions on weight loss, dropouts during the intervention, and weight maintenance after 1 year].

OBJECTIVES

To compare the effects of weekly or bi-weekly dietary sessions with the same number of total lecture hours, periods, and lecture contents on weight loss, dropouts during the intervention, and the weight loss maintenance after 1 year.

METHODS

The study included 52 middle-aged women with at least 1 risk factor for cardiovascular disease (i.e., obesity, hypertension, dyslipidemia, and hyperglycemia) who were encouraged to lose weight. Thirty-seven women were assigned to the weekly class (self-selected weekly class group: n=26) or the bi-weekly class (self-selected bi-weekly class group: n=11) based on their preference. Fifteen women were assigned to the bi-weekly class against their will (bi-weekly class group). All groups participated in the same number of sessions (total, 26 h), and were instructed to reduce their dietary intakes to 1200 kcal/day for 13 weeks. The self-selected weekly class group attended a 2-h instructional session every week, whereas both the bi-weekly class groups received 1-h sessions twice a week. Data on the body weight of the participants was collected 1 year after the intervention using a self-administered questionnaire via mail.

RESULTS

The self-selected bi-weekly class group had significantly fewer dropouts (self-selected weekly class group: 5 persons, 19.2%; self-selected bi-weekly class group: 1 person, 9.0%; bi-weekly class group: 8 persons, 53.3%; P<0.05). There was a significant decrease in weight (P<0.05) in all 3 groups during the intervention (self-selected weekly class group: -4.3±2.7 kg, self-selected bi-weekly class group: -6.7±3.0 kg, bi-weekly class group: -6.0±3.4 kg). However, weight loss in the self-selected bi-weekly class group was significantly greater than that in the other 2 groups. A significant change in body weight at the 1-year follow-up was not observed in any group (self-selected weekly class group: +0.4±1.3 kg, self-selected bi-weekly class group: -0.1±2.3 kg, bi-weekly class group: +0.5±0.6 kg). Repeated-measures ANOVA (time×group) revealed no significant interactions in weight loss.

CONCLUSION

These results suggest that a greater frequency of dietary sessions contributes to weight loss, while a lesser frequency of dietary sessions contributed to a decrease in questionnaire recovery rates. The dropout rate in the self-selected weekly and bi-weekly class groups was lesser than that in the bi-weekly class group. Therefore, dietary sessions tailored to the needs of the participants might decrease the dropout rate.