Context Although commercial weight loss programs provide treatment to millions
of clients, their efficacy has not been evaluated in rigorous long-term trials.
Objective To compare weight loss and health benefits achieved and maintained through
self-help weight loss vs with a structured commercial program.
Design and Setting A 2-year, multicenter randomized clinical trial with clinic visits at
12, 26, 52, 78, and 104 weeks conducted at 6 academic research centers in
the United States between January 1998 and January 2001.
Participants Overweight and obese men (n = 65) and women (n = 358) (body mass index,
27-40) aged 18 to 65 years.
Intervention Random assignment to either a self-help program (n = 212) consisting
of two 20-minute counseling sessions with a nutritionist and provision of
self-help resources or to a commercial weight loss program (n = 211) consisting
of a food plan, an activity plan, and a cognitive restructuring behavior modification
plan, delivered at weekly meetings.
Main Outcome Measures Weight change was the primary outcome measure. Secondary outcomes included
waist circumference, body mass index, blood pressure, serum lipids, glucose,
and insulin levels.
Results At 2 years, 150 participants (71%) in the commercial group and 159 (75%)
in the self-help group completed the study. In the intent-to-treat analysis,
mean (SD) weight loss of participants in the commercial group was greater
than in the self-help group at 1 year (−4.3 [6.1] kg vs −1.3 [6.1]
kg, respectively; P<.001) and at 2 years (−2.9
[6.5] kg vs −0.2 [6.5] kg, respectively; P<.001).
Waist circumference (P = .003) and body mass index
(P<.001) decreased more in the commercial group.
Changes in blood pressure, lipids, glucose, and insulin levels were related
to changes in weight in both groups, but between-group differences in biological
parameters were mainly nonsignificant by year 2.
Conclusion The structured commercial weight loss program provided modest weight
loss but more than self-help over a 2-year period.