Weight Loss Maintenance in Primary Care
Principal Investigator:
Michael Lowe, Ph.D.
Abstract:
The rising prevalence of obesity is taking an increasingly severe toll
on the nation’s health. The present
proposal is aimed at evaluating two interventions for weight loss maintenance
in primary care patients. The
participants (N=280) will be recruited by their physicians and will initially
lose weight for 12 weeks using a meal replacement-supplemented diet and the
LEARN manual. At the end of the
weight loss period participants will be assigned at random to one of four
groups, formed by crossing two factors.
The first factor is the presence or absence of meal replacements (MR+
and MR-) to facilitate weight loss maintenance. The second factor is the presence or
absence of a Reduced Energy Density Eating (REDE+ and REDE-) program. The four treatment conditions to be
tested during the weight loss maintenance period are MR-/REDE-, MR+/REDE-,
MR-/REDE+, and MR+/REDE+. All
participants will receive the LEARN manual plus treatment manuals consistent
with their weight maintenance condition.
They will be called by an Obesity Specialist regularly throughout the
year-long intervention. The aim of
the study is to test the hypothesis that: 1) the MR+/REDE- and MR-/REDE+ groups
will maintain their weight losses and related behavioral and nutritional
changes better than the LEARN-only (MR-/REDE-) group, and 2) the MR+/REDE+
group will maintain their weight loss and related changes better than the
MR-/REDE-, MR+/REDE-, and MR-/REDE+ groups. This study is important because it
may identify better ways of promoting long-term improvements in the diet and
body weight of obese patients seen in primary care settings. Outcome measures,
which will be collected at baseline and at 6, 12, 24, and 36 months, will
assess changes in body weight and composition, nutritional composition of the
diet, measures of eating control, obesity-related quality of life, physical
activity, patient and physician satisfaction ratings, and several medical risk
factors (blood pressure, lipids, and HbA1c).
Specific Aims:
The rising prevalence of obesity is taking an increasingly severe toll
on the nation’s health. Achieving and maintaining a medically significant
weight loss is of particular importance for those overweight individuals who
have, or who are at greatest risk for developing, one of the many medical
conditions associated with obesity. In line with this objective, the present
proposal is aimed at producing long-term changes in nutritional intake and body
weight in primary care practices where such patients are routinely
treated.
Traditional lifestyle change weight control programs produce medically
significant weight reductions for most individuals participating in them.
However, the weight losses achieved in these programs – and the health
improvements that result from them – typically dissipate over time. No
satisfactory solution to the long-term weight regain problem has yet been identified.
Lifestyle change programs for obesity are primarily based on social
learning theory. In a paper
recently published in Obesity Research,
we reviewed the assumptions upon which traditional lifestyle change treatments
are based, and compared these assumptions to a variety of recent biobehavioral research findings on factors controlling
eating and weight regulation. This analysis forms the foundation of the biobehavioral model of eating regulation upon which the
present application is based. The major aim of the proposed research is to
demonstrate that two nutritionally-focused interventions derived from this biobehavioral model of eating regulation will produce
superior long-term maintenance of changes in eating behavior, the nutritional
composition of the diet, medical risk factors and weight losses relative to a
traditional lifestyle change program (based on the LEARN manual).
The first intervention will replace one meal and one snack per day with
a meal replacement (MR) to promote weight loss maintenance. The second intervention will teach
participants to reduce the energy density of their diet while preserving its
palatability to the greatest extent possible (the Reduced Energy Density Eating
or REDE intervention. These two
factors will be crossed, permitting a test of the effects of the presence or
absence of MRs (MR+ vs. MR-) and the presence or
absence of REDE (REDE+ vs. REDE-) on weight loss maintenance and related
outcomes.
Aim 1: To test the hypothesis that the MR and
REDE interventions, when added separately to the LEARN program, will produce
superior weight loss maintenance compared to a LEARN-only intervention.
There is also reason to hypothesize that the effects of MRs and REDE should be complementary rather than
redundant. The primary benefit of MRs stems from a reduction in energy intake at the meals or
snacks when they are consumed. The
primary benefit of REDE is to produce changes in the overall energy density and
nutritional composition of the diet.
Also supporting the possibility of additive effects is the likelihood
that some individuals will not adhere consistently to MRs
during maintenance. In such cases,
the simultaneous availability of the REDE program will provide an alternative
way to control energy intake.
Finally, in the condition where both MRs and
REDE are available during maintenance, some participants might use MRs to reverse weight gains and REDE to prevent weight
gains (i.e., sustain weight maintenance), another potential type of
complementariness.
Aim 2: To test the hypothesis that the a
maintenance condition that combines MRs and REDE will
produce better maintenance of weight losses than either individual component
and than the LEARN-only condition.
Aim 3: To test the hypothesis that the two
conditions receiving the REDE intervention will experience longer-lasting
improvements in the energy density and nutritional composition of the diet
compared to the two non-REDE conditions.
Primary care represents an ideal setting for the delivery of weight
management programs because physicians are potentially powerful agents of
change, are responsible for detecting and treating medical conditions
associated with obesity, and see their patients periodically over lengthy
periods of time. Participants will
be male and female patients attending one of four primary care practices
affiliated with Drexel University College of Medicine. Outcome measures will
include body weight and composition, energy density and nutritional composition
of the diet, eating control, physical activity, obesity-related qualify of
life, and obesity-related health risk factors. These measures will be collected
at baseline, and 6, 12, 24 and 36 months following treatment initiation.