134 Obesity
biweekly meetings were scheduled over a seven-month pe-
riod. Although attendance at the peer group meetings was
high (67%), no advantage was observed in terms of adher-
ence or weight change during the maintenance period com-
pared to a control condition. The results of a long-term
follow-up showed a trend toward better maintenance of
weight lost in the peer support group compared to the control
condition. Wing and Jeffery (1999) recently tested the effects
of recruiting participants alone or with three friends or family
members. The researchers used a partially randomized study
in assigning subjects (recruited alone versus with friends) to
receive either standard behavior therapy or behavior therapy
with social support training. The results of a six-month
follow-up showed that participants who were recruited with
friendsandwere provided social support training maintained
66% of their initial weight losses. In contrast, the individuals
who entered the study alone and received standard treatment
maintained only 24% of their initial losses.
Exercise/Physical Activity
The association between long-term weight loss and increased
physical activity is a common “nding in correlational studies
(e.g., Harris, French, Jeffery, McGovern, & Wing, 1994;
McGuire, Wing, Klem, Lang, & Hill, 1999; Sherwood,
Jeffery, & Wing, 1999). Nonetheless, an important question
remains as to whether the addition of exercise or physical
activity can improve long-term outcome in the treatment of
obesity (Garrow, 1995). Wing (1999) recently reviewed the
results of randomized controlled trials of exercise in the treat-
ment of obesity. Wing found that only 2 of 13 studies showed
signi“cantly greater initial weight losses for the combination
of diet plus exercise versus diet alone, and only 2 of 6 studies
with follow-ups of one or more years showed signi“cantly
better maintenance of lost weight for diet plus exercise versus
diet alone. However, in all the studies reviewed, the direction
of the “ndings favored treatment that included exercise.
Wing noted that the short duration of treatments and the rela-
tively low levels of exercise prescribed in many of the stud-
ies may have accounted for the modest effects of exercise on
weight loss.
In addition, treatment integrity represents an important
problem in controlled trials of exercise. Participants assigned
to exercise conditions often vary greatly in their adherence to
their exercise prescriptions, and subjects assigned to •diet
onlyŽ conditions sometimes initiate exercise on their own.
Compromises in treatment integrity can obscure the effects of
exercise interventions. For example, Wadden and his col-
leagues (1997) investigated the impact of adding aerobic ex-
ercise, strength training, and their combination, to a 48-week
behavioral treatment program. None of the exercise additions
improved weight loss or weight-loss maintenance, compared
to behavior therapy with diet only. Across all conditions, ad-
herence to exercise assignments was highly variable, espe-
cially during follow-up. Nonetheless, the researchers found a
signi“cant positive association between exercise and long-
term weight loss. Participants who indicated that they •exer-
cised regularlyŽ had long-term weight losses (12.1 kg) nearly
twice as large as those who described themselves as •non-
exercisersŽ (6.1 kg).
Given the potential bene“ts of exercise for long-term
management of weight, how can adherence to physical activ-
ity regimens be improved? The various strategies that have
been examined include: home-based exercise, the use of
short bouts of exercise, the provision of home exercise equip-
ment, monetary incentives for exercise, and posttreatment
programs focused exclusively on exercise.Home-Based ExerciseAlthough group-based exercise programs offer the opportu-
nity for enhanced social support, over the long run such
bene“ts may be limited by potential barriers that one must
overcome in meeting with others to exercise at a designated
time and location. In contrast, home-based exercise offers a
greater degree of ”exibility and fewer obstacles. Perri, Martin,
Leermakers, Sears, and Notelovitz (1997) investigated the use
of home-based versus supervised group-based exercise pro-
grams in the treatment of obesity. After six months, both
approaches resulted in signi“cant improvements in exercise
participation, cardiorespiratory “tness, eating patterns, and
weight loss. However, over the next six months, participants
in the home-based condition completed a signi“cantly higher
percentage of prescribed exercise sessions than subjects in the
group program (83.3% versus 62.1%, respectively). More-
over, at long-term follow-up, the participants in the home-
based program displayed signi“cantly better maintenance of
lost weight, compared to subjects in the group-based program.Personal Trainers/Financial IncentivesThe use of personal trainers and “nancial incentives have
been tested as strategies to improve exercise adherence and
long-term weight loss (Jeffery, Wing, Thorson, & Burton,
1998). Personal trainers exercised with participants and
made phone calls reminding them to exercise. In addition,
participants could earn $1 to $3 per bout of walking. The use
of personal trainers and “nancial incentives both increased
attendance at supervised exercise sessions, but neither
improved weight loss. In fact, participants in the control