Factors Associated with Achievement of Clinically Significant Weight Loss by Women in a National Nonprofit Weight Loss Program.

Background: Clinically significant weight loss (CSWL) is ≥5% of initial weight. The purpose of the study is to determine factors associated with women achieving CSWL in Take Off Pounds Sensibly (TOPS), a national, nonprofit weight loss program.

Methods: This is a retrospective analysis of 48,674 females who joined TOPS from 2005 to 2011 and had a birth date in the database. Predictors of CSWL were evaluated using log-binomial regression and adjusted relative risks [99% CI] for participant age, initial weight, number of members per chapter, and chapter age.

Results: Older women were more likely to achieve CSWL, with women ≥70 years 1.23 (1.18, 1.28) times more likely to achieve CSWL compared to women 18 to <45 years. Women who weighed 113 to <136 kg and ≥136 kg were 1.06 (1.02, 1.10) and 1.07 (1.02, 1.14) times more likely to achieve CSWL compared to women <80 kg, respectively. Women in chapters with 25 to <35 members and ≥35 members more were 1.09 (1.05, 1.13) and 1.14 (1.10, 1.18) times more likely to achieve CSWL than those in chapters with less than 15 members. Women in older chapters were less likely to achieve CSWL, with women in chapters 10 to 20 years old 0.95 (0.92, 0.99) times as likely to lose weight as those in chapters less than 10 years old.

Conclusions: Women in TOPS were more likely to achieve CSWL if older, ≥113 kg, and in larger, newer chapters. Future studies should address ways to modify the program to improve achievement of CSWL.