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Abstract

The prevalence of obesity and its associated health problems have increased sharply in the past 2 decades. New revisions to Medicare policy will allow funding for obesity treatments of proven efficacy. The authors review studies of the long-term outcomes of calorie-restricting diets to assess whether dieting is an effective treatment for obesity. These studies show that one third to two thirds of dieters regain more weight than they lost on their diets, and these studies likely underestimate the extent to which dieting is counterproductive because of several methodological problems, all of which bias the studies toward showing successful weight loss maintenance. In addition, the studies do not provide consistent evidence that dieting results in significant health improvements, regardless of weight change. In sum, there is little support for the notion that diets lead to lasting weight loss or health benefits.
Medicare’s Search for Effective Obesity Treatments
Diets Are Not the Answer
Traci Mann, A. Janet Tomiyama, Erika Westling, Ann-Marie Lew, Barbra Samuels, and Jason Chatman
University of California, Los Angeles
The prevalence of obesity and its associated health prob-
lems have increased sharply in the past 2 decades. New
revisions to Medicare policy will allow funding for obesity
treatments of proven efficacy. The authors review studies of
the long-term outcomes of calorie-restricting diets to as-
sess whether dieting is an effective treatment for obesity.
These studies show that one third to two thirds of dieters
regain more weight than they lost on their diets, and these
studies likely underestimate the extent to which dieting is
counterproductive because of several methodological
problems, all of which bias the studies toward showing
successful weight loss maintenance. In addition, the studies
do not provide consistent evidence that dieting results in
significant health improvements, regardless of weight
change. In sum, there is little support for the notion that
diets lead to lasting weight loss or health benefits.
Keywords: diets, weight loss maintenance, interventions,
obesity, Medicare
L
evels of obesity are increasing throughout the world,
and in the United States, health problems associated
with obesity are a leading cause of mortality, second
only to health problems associated with smoking (Mokdad,
Marks, Stroup, & Gerberding, 2005). About 15% of the
American population was obese
1
in 1980. Over the next 20
years, the percentage of obese individuals increased dra-
matically, and 34% of the population is now considered
obese (2003–2004; National Center for Health Statistics,
2006).
In light of the rapid increase in the prevalence of
obesity, it is not surprising that Medicare has recently
altered its policy on covering obesity treatments. In July
2004, the Centers for Medicare and Medicaid Services
(CMS) deleted the phrase “obesity is not considered an
illness” from its coverage manual. This six-word deletion
opened the door for Medicare to cover treatments for
obesity itself, rather than just treatments for specific con-
ditions thought to be caused by obesity, such as diabetes
and hypertension. However, CMS did not go so far as to
classify obesity as a disease, and according to CMS, dis-
eases and illnesses are distinct entities with different cov-
erage rules. Treatments for diseases must be included in
coverage, whereas treatments for obesity— classified as an
illness rather than a disease—will have to meet higher
standards of effectiveness
2
to be covered (Higgins, 2004).
Medicare uses a formal process to make policy deci-
sions to grant coverage for specific treatments. When an
official request for coverage of a particular treatment is
made, a compilation of currently available medical and
scientific information regarding the treatment is submitted
to CMS. CMS then reviews the submitted data and scien-
tific literature as well as all other relevant evidence. The
staff may make a decision based on this information, or
they may determine that an external review is necessary.
After all external reviews have been conducted, CMS
makes a final decision and then provides formal written
instruction to claims processors about what claims will be
covered under particular circumstances (“Medicare Pro-
gram,” 2003).
Throughout this decision process, scientific evidence
must be evaluated and its strength must be assessed. A
recent effort has been made to create a single system for
grading the quality of evidence and strength of recommen-
dations for all types of medical procedures (GRADE Work-
ing Group, 2004). According to that system, called the
GRADE system, four main assessments must be made.
First, judgments are made about the quality of evidence for
each distinct outcome examined, across all available stud-
ies. These judgments are based on study design, study
quality (i.e., the methods and execution of the study),
consistency of results across studies, and directness or
generalizability of the studied samples, treatments and
measures. Second, if there are many outcome measures
evaluated, judgments are made about which outcomes are
Traci Mann, A. Janet Tomiyama, Erika Westling, Ann-Marie Lew, Barbra
Samuels, and Jason Chatman, Department of Psychology, University of
California, Los Angeles.
We acknowledge the helpful comments of David Creswell, David
Frederick, Kelli Garcia, Johanna Jarcho, Christine Dunkel Schetter, Ann-
ette Stanton, Shelley Taylor, and Andrew Ward; the research assistance of
Daniela Pallafachina and Rachel Shasha; and especially the insights of
Kathleen Hoffman Lambird. This work was partially supported by Na-
tional Institute of Mental Health Grant R01 63795 to Traci Mann.
Correspondence concerning this article should be addressed to Traci
Mann, Department of Psychology, University of California, Los Angeles,
Franz Hall, Box 951563, Los Angeles, CA 90095-1563. E-mail:
mann@psych.ucla.edu
1
Obesity is defined as having a body mass index (BMI; kg/m
2
)of30
or greater. Overweight is a BMI of 25–30.
2
Although we are aware of the distinction between the terms efficacy
and effectiveness used in the clinical intervention literature, we use the
terms interchangeably.
220 April 2007
American Psychologist
Copyright 2007 by the American Psychological Association 0003-066X/07/$12.00
Vol. 62, No. 3, 220 –233 DOI: 10.1037/0003-066X.62.3.220
critical. Third, the overall quality of evidence across these
critical outcomes is assessed. Fourth, the balance of bene-
fits and harms is considered.
In assessing whether Medicare should fund calorie-
restricting diets for the treatment of obesity, we shall at-
tempt to answer the questions posed by the GRADE sys-
tem. We begin by evaluating the quality of evidence for the
most common obesity treatment—the severe restriction of
calorie intake (which we will refer to as dieting
3
)—accord-
ing to one primary outcome measure: sustained weight
loss. We focus on long-term weight loss because short-term
weight loss is not a cure for obesity. Population-level
changes in obesity (and presumably its concomitant health
problems) will only occur if losses are maintained. Direct
indicators of health, such as blood pressure, cholesterol
levels, disease incidence, and even mortality, are also im-
portant outcomes of obesity treatments, and we discuss
these outcomes in the few long-term studies that include
them. Finally, we briefly discuss the balance of benefits and
harms associated with using diets as a treatment for obe-
sity.
According to the GRADE system, the first factor to
consider in evaluating the quality of scientific evidence is
the study design. The system assigns a higher starting grade
to randomized trials and a lower starting grade to observa-
tional studies (GRADE Working Group, 2004). The start-
ing grade is then adjusted on the basis of the quality of the
study methods and execution. We first discuss long-term
randomized trials of diets (higher starting grade) and then
two different types of observational studies of diets (lower
starting grades). In each section, we assess the quality of
the study methods and execution as well as the consistency
and directness of the findings.
Long-Term Effects of Dieting
Reviews of the scientific literature on dieting (e.g., Garner
& Wooley, 1991; Jeffery et al., 2000; Perri & Fuller, 1995)
generally draw two conclusions about diets. First, diets do
lead to short-term weight loss. One summary of diet studies
from the 1970s to the mid-1990s found that these weight
loss programs consistently resulted in participants losing an
average of 5%–10% of their weight (Perri & Fuller, 1995).
Second, these losses are not maintained. As noted in one
review, “It is only the rate of weight regain, not the fact of
weight regain, that appears open to debate” (Garner &
Wooley, 1991, p. 740).
The more time that elapses between the end of a diet
and the follow-up, the more weight is regained. For exam-
ple, in a study in which obese patients were starved in the
hospital for an average of 38 days, patients were followed
for varying lengths of time after the starvation period.
Among patients who were followed for under two years,
23% gained back more weight than they had lost. Among
patients who were followed for two or more years, 83%
gained back more weight than they lost (Swanson &
Dinello, 1970). Even in the studies with the longest fol-
low-up times (of four or five years postdiet), the weight
regain trajectories did not typically appear to level off (e.g.,
Hensrud, Weinsier, Darnell, & Hunter, 1994; Kramer, Jef-
fery, Forster, & Snell, 1989), suggesting that if participants
were followed for even longer, their weight would continue
to increase. It is important for policymakers to remember
that weight regain does not necessarily end when research-
ers stop following study participants.
Long-Term Randomized Studies
The most rigorous designs in studies of long-term weight
loss maintenance are those that randomly assign individu-
als to a diet condition or to a no-diet condition and then
follow them over time. Such studies allow causal conclu-
sions to be drawn about the effects of the diet on weight,
and they are particularly useful because individuals who do
not go on diets are often found to slowly gain weight over
time (e.g., Burke et al., 1996; Shah, Hannan, & Jeffery,
1991). Very few such studies include long-term follow-ups
that allow for clear comparisons between the weight of
dieters and the weight of control participants, presumably
because it is difficult to require obese individuals with an
interest in dieting to remain in wait-list control groups for
extended periods of time.
By conducting searches of online databases, inspect-
ing studies listed in the reference sections of several large
reviews of diet outcome studies (Astrup & Rossner, 2000;
Black, Gleser, & Kooyers, 1990; Foreyt, Goodrick, &
Gotto, 1981; Jeffery et al., 2000; Leon, 1976; Perri, 1998;
Perri & Fuller, 1995; Saris, 2001), and examining the
reference sections of the diet outcome studies themselves,
3
The term dieting has been used to refer to a wide range of behav-
iors, but we use it solely to refer to the specific behavior of severely
restricting one’s calorie intake in order to lose weight.
Traci Mann
221April 2007
American Psychologist
we were only able to locate seven studies
4
that randomly
assigned participants to a diet or a wait-list control group,
follow them for at least two years, and then report on
weight outcomes. The diets in several of these studies are
combined with other lifestyle interventions, including ex-
ercise, but we include these studies because they are the
most rigorous type of diet studies and because they have
control groups that allow for useful comparisons. In fact,
only one of these seven studies is a formal diet study
without additional interventions. One is an obesity preven-
tion program, and five are clinical trials of large-scale
interventions designed to reduce risk for heart disease or
diabetes or to prevent or control hypertension.
The formal diet study followed participants for 2.5
years (Jeffery & Wing, 1995). Participants were randomly
assigned to one of four types of diets or to a wait-list
control group. At the end of the 2.5-year follow-up, par-
ticipants assigned to the wait-list control group did not
show a statistically significant weight gain, and their
weight change was only marginally different than that of
the dieters. The dieters had kept off an average of only 1.7
kg (3.7 lb). This methodologically rigorous study shows
that in the long term, dieters do not fare notably better than
nondieters.
Another study compared individuals assigned to either
of two obesity prevention programs with those assigned to
a wait-list control group (Jeffery & French, 1999). The
focus of the obesity prevention programs was to encourage
participants to pay attention to their weight and to make
small changes to their diet and exercise habits. After three
years, there were no significant differences in the weight
change between prevention participants and wait-list par-
ticipants. Participants gained an average of 1.6 kg (3.5 lb),
and the researchers concluded that the obesity prevention
program had not succeeded.
Five different large-scale clinical trials randomly as-
signed individuals
5
to interventions with many compo-
nents, in which one component was a focus on losing
weight through dieting. These interventions were aimed at
large groups of participants, and they tended to last several
years, so there were not always rigorous controls on
whether particular individuals actually participated in the
intervention (and whether control participants truly did not
diet). Still, these studies provide information on the long-
term weight trajectories of dieters compared with non-
dieters.
The study with the most promising results in terms of
health outcomes randomly assigned overweight or obese
individuals at risk for diabetes to a lifestyle intervention
involving diet and exercise or to one of two control groups
(Diabetes Prevention Program Research Group, 2002). At a
three-year follow-up, participants in the lifestyle interven-
tion lost an average of about 4 kg (8.8 lb), while partici-
pants in the placebo control group had gained about 0.5 kg
(1.1 lb).
6
In this same time frame, however, the lifestyle
intervention reduced the incidence of diabetes by 58%
compared with the placebo control group. These results
may not directly be due to the diet part of the intervention,
and in fact participants in the lifestyle intervention engaged
in large amounts of physical activity (averaging 227 min-
utes per week), and this may be the potent factor. As we
discuss in detail below, exercise seems to be an important
factor in weight and health outcomes. In addition, the
findings may not apply to all obese people, but rather just
to the specially chosen subset of obese people included in
the study— obese people (and overweight people) with
elevated plasma glucose concentrations, a risk factor for
diabetes.
The largest weight loss occurred, not surprisingly, in
the study with the shortest follow-up time. In that study of
a nonpharmacologic intervention for older individuals with
hypertension, participants in the diet conditions maintained
an average weight loss of 4.7 kg (10.4 lb) at the 2.5-year
follow-up, whereas control participants maintained a loss
of 0.9 kg (1.9 lb; Whelton et al., 1998). This study also
included health outcomes and found no significant differ-
ence between participants in the diet condition compared
with the control condition in systolic or diastolic blood
pressure or in the number of cardiovascular events (e.g.,
strokes, myocardial infarction) experienced. However, par-
ticipants in the diet condition did appear to have a reduced
need for antihypertensive drugs.
4
Several studies that are often cited as support for the long-term
success of diets followed individuals for less than one year (Foreyt &
Kennedy, 1971), six months (e.g., Klem, Wing, Simkin-Silverman, &
Kuller, 1997), or even less time (Dahlkoetter, Callahan, & Linton, 1979;
Presnell & Stice, 2003).
5
Studies that randomly assigned entire communities to interventions
and control groups are not included here because of the low power
inherent in such designs (Fortmann, Williams, Hulley, Haskell, & Far-
quhar, 1981; Jeffery et al., 1995; Taylor et al., 1991).
6
These numbers were not reported in the article but were estimated
from a graph depicted in it.
A. Janet
Tomiyama
222 April 2007
American Psychologist
A study designed to prevent hypertension (Hyperten-
sion Prevention Trial Research Group, 1990) and a study
designed to control hypertension (Stamler et al., 1987)
followed participants for three and four years, respectively,
and found similar results in terms of weight loss but dif-
fered on the health outcomes. In both studies, participants
in the diet-type interventions maintained an average weight
loss of 1.8 kg (3.9 lb), whereas corresponding control
participants gained an average of 1.8 kg. In the hyperten-
sion prevention study (Hypertension Prevention Trial Re-
search Group, 1990), participants on the diet did show
significantly greater reductions in diastolic and systolic
blood pressure over the three years of the study than did
control participants, though these differences were clini-
cally small (1.8 millimeters of mercury and 2.4 millimeters
of mercury, respectively). Diet and control participants did
not differ in whether they needed drug treatment for hy-
pertension, nor did they differ in periods of hospitalization
or deaths. In the hypertension control study (Stamler et al.,
1987), hypertensive participants were assigned to a control
group or to an intervention that combined a diet, sodium
restriction, and alcohol reduction. They were then removed
from their hypertension medication. The most important
outcome of the study was whether participants were able to
keep their blood pressure low enough to remain off their
hypertension medication. On this outcome, 39% of partic-
ipants in the diet intervention succeeded after four years,
whereas only 5% of control participants succeeded. Al-
though an important and clinically significant finding, it
likely fails the test of directness recommended by the
GRADE system. First, the intervention was not solely a
diet but also required sodium and alcohol reduction, and
the beneficial effects of it may be due to those components.
Second, the intervention is an effective treatment for hy-
pertension, not obesity. As such, Medicare might fund it for
individuals with hypertension, regardless of whether they
are obese, and the new policy on treating obesity per se is
not necessary for this to occur.
Participants in the remaining study were individuals at
risk for cardiovascular disease, according to their diastolic
blood pressure, cholesterol level, and cigarette use. About
two thirds of the participants were hypertensive. Partici-
pants were assigned to an intervention designed to lower
cardiovascular risk factors or to a usual-care control group
and then were followed for six years (Grimm, Cohen,
Smith, Falvo-Gerard, & Neaton, 1985). The intervention
included a low-cholesterol diet and instruction in smoking
cessation, among other components. At the 6-year follow-
up, the average weight loss maintained for individuals in
the intervention condition was about 0.5 kg (1.1 lb),
whereas control participants gained an average of 0.5 kg.
Blood pressure levels decreased for participants in both
conditions, but the decreases were significantly larger for
participants in the intervention than for participants in the
control group. However, this difference is likely attribut-
able to the fact that significantly more intervention partic-
ipants were taking antihypertensive medication than con-
trol participants throughout the study. Mortality rates did
not differ between participants in the two groups at the
6-year follow-up, but mortality rates were lower for inter-
vention participants at a 10.5-year follow-up (Multiple
Risk Factor Intervention Trial Research Group, 1990).
These mortality changes may have been due to smoking
changes rather than dietary ones (or to the use of the
antihypertensive medications). The directness of this study
to obesity treatment must be questioned as well, as the
participants were not necessarily obese, and in fact partic-
ipants who weighed more than 50% over their ideal weight
(according to height and weight charts) were excluded.
In sum, across these studies, there is not strong evi-
dence for the efficacy of diets in leading to long-term
weight loss. In two of the studies, there was not a signifi-
cant difference between the amount of weight loss main-
tained by participants assigned to the diet conditions and
those assigned to the control conditions. In the three studies
that did find significant differences, the differences were
quite small.
7
The amount of weight loss maintained in the
diet conditions of these studies averaged 1.1 kg (2.4 lb),
ranging from a 4.7-kg (10.4-lb) loss to a 1.6-kg (3.5-lb)
gain. Participants in the control groups averaged weight
gains of 0.6 kg (1.3 lb; ranging from losses of 0.9 kg [1.9
lb] to gains of up to 1.8 kg [3.9 lb]). The most positive
conclusion is that dieting slows the slight weight gain that
occurs with age among the average nondieter, and even this
slight weight gain was not seen in all of the no-diet control
groups. It is hard to call these obesity treatments effective
when participants maintain such a small weight loss.
Clearly, these participants remain obese.
7
Two studies did not report sufficient information to assess whether
differences were significant.
Erika
Westling
223April 2007
American Psychologist
There is some evidence for the effectiveness of diets
in leading to other beneficial health outcomes, particularly
in helping people stay off antihypertensive drugs and pre-
venting diabetes, but this evidence is not consistent across
the studies. In addition, it is not possible to detect whether
the diet components of these interventions were potent, as
the interventions all contained other components that may
have reduced hypertension or prevented diabetes (e.g., in-
creases in physical activity, reductions in smoking, alcohol
use, and sodium). In addition, the effects on blood pressure
seem to be specific to individuals who have hypertension,
rather than to individuals who are overweight, and hence
those interventions are more aptly labeled hypertension
treatments—not obesity treatments—and might be offered
to hypertensive individuals regardless of their weight. Sim-
ilarly, only individuals with a specific risk factor for dia-
betes were included in the diabetes prevention study, so its
generalizability to obese individuals in general is not
known. Finally, although all of the studies in this section
used strong research designs, in studies that tracked partic-
ipants for such long periods of time, it is difficult to retain
all participants in follow-up assessments. It is not entirely
clear from the research reports exactly which participants
were included at each assessment point, a problem that we
discuss in more detail below.
Observational Studies: Type 1. Long-Term
Follow-Ups Without Control Groups
Most conclusions in the literature on the long-term out-
comes of dieting come from studies in which participants in
structured weight loss programs are recontacted from two
to five years after the diet ends. These studies do not
include control groups of nondieting comparison partici-
pants, so no causal conclusions about the effects of the
diets can be drawn from them. Despite this problem, these
studies do give a useful sense of the weight trajectories of
individuals who go on diets.
By searching online databases and reviews of diet
studies (Anderson, Konz, Frederich, & Wood, 2001; As-
trup & Rossner, 2000; Black, Gleser, & Kooyers, 1990;
Foreyt et al., 1981; Jeffery et al., 2000; Leon, 1976; Perri,
1998; Perri & Fuller, 1995; Saris, 2001), we were able to
locate 14 studies that followed participants for at least four
years after a diet (see Table 1 for the features of these
studies). The average weight loss on these diets was 14 kg
(30.8 lb), and by the long-term follow-up, participants had
gained back all but 3 of those kilograms (6.6 lb).
Eight of the studies reported (or made it possible to
compute) the percentage of participants who weighed more
at follow-up than before they went on the diet. These rates
averaged 41% and ranged from 29% (Pekkarinen & Mus-
tajoki, 1997) to 64% (Wadden, Sternberg, Letizia,
Stunkard, & Foster, 1989), including one study that found
that 50% of the participants weighed more than 5 kg (11 lb)
above their starting weight by five years after the diet
(Foster, Kendall, Wadden, Stunkard, & Vogt, 1996). Of
note, studies always report the percentage of participants
who manage to keep off some percentage of the lost
weight, but only a subset reported on participants for whom
the diet was counterproductive, even though this percent-
age is typically larger than the percentage who kept off
substantial weight.
Although the findings reported so far give a bleak
picture of the outcomes of diets, there are four reasons why
the actual effectiveness of diets is even worse. First, the
studies have very low follow-up rates, and this is especially
true for the longer term follow-ups. Second, many of the
participants in these studies self-reported their weight over
the phone or by mail. Third, most of the studies confound
effects of the diet with effects of exercise. Fourth, a sub-
stantial percentage of participants in these studies have
been on other diets since the studied diet ended. Each of
these methodological problems biases the studies toward
showing more effective maintenance of the lost weight. We
will briefly consider each of these problems for the 14
studies in which individuals were followed for four or more
years after the diet ended.
Follow-up rates. The follow-up rates in these
studies were quite low (see Table 1). Overall, 33% of the
original participants in these diet studies returned for their
long-term follow-up. Not surprisingly, the four studies with
the highest follow-up rates (from 81% to 88%) were among
the five studies with the smallest sample sizes (36 par-
ticipants). Eight of the studies had follow-up rates lower
than 50%.
It is generally believed that low follow-up rates bias
the results of diet studies, making the diets appear to be
more effective than they were, because individuals who
gain back large amounts of their weight are particularly
unlikely to show up for follow-up tests. In one study,
researchers examined the weight trajectories of participants
on the basis of how many follow-up appointments they
attended (Hovell et al., 1988). The initial amount of weight
Ann-Marie
Lew
224 April 2007
American Psychologist
Table 1
Features of Diet Studies With Long-Term Follow-Ups (and No Control Groups)
Study
Years of
follow-up N
%ofN
in follow-up
% self-
reporting
weight
% on additional diets (or mean
number of diets)
% reporting
regular
exercise
Mean change
from baseline to
end of diet (kg)
Mean change
from baseline to
follow-up (kg)
% regain all lost weight
(or more)
Anderson et al. (1999) 5–7 52 12 30 20
a
29.7 5.2
Foster et al. (1996) 5 55 47 0 65 (M 1 diet) 21.1 3.6 50% were 5kg
above baseline
Graham et al. (1983) 4.5 60 43 0 (M 3 types of treatments) 35 4.5 3.3
Hensrud et al. (1994) 4 21 88 0 50
b
22 12.5 1.6 37
Jordan et al. (1985) 5 111 25 100 8.4 5.2
Kramer et al. (1989) 4 152 77 7 (M 1.3 diets/year) 11.9 3.1 38
Lantz et al. (2003) 4 54 48 0 7.0 3.3
Murphy et al. (1985) 4 25 33 0 38 (M 1.6 programs) 46 7.7 0.5
Pekkarinen and Mustajoki
(1997)
5.5 24 88 13 12% lost 10 kg on other
diets
c
22.9
d
5.8 29
Stalonas et al. (1984) 5 36 81 22 (M 2 diets)
e
4.7 0.7 46
Stunkard and Penick
(1979)
52681 63 8.8 5.4 31
Wadden and Frey
(1997)
5 281 22 100 43 25.6 6.6 32
Wadden et al. (1989) 5 55 72 47 55 14.6 0.6 64
Walsh and Flynn (1995) 4.5 143 47 100 36
f
21.4 5.1
Note. Dashes indicate that data were not reported. 1 kg 2.21 lb.
a
20% of larger sample entered special “restart” classes for former participants who failed to maintain their weight or desired further weight loss.
b
50% engaged in informal diet attempts.
c
It is unclear how many
of these participants were in the restrictive diet being evaluated here versus in another study condition. The authors do not report how many participants were on additional diets but lost less than 10 kg on them.
d
This
mean only includes the 50% of participants who showed up for more than half of the meetings.
e
Participants exercised a mean of 15.6 months (of 60).
f
Percentage not given, but authors stated that regular
exercisers maintained significantly greater weight loss than nonexercisers.
225April 2007
American Psychologist
lost did not differ among these participants, but participants
who showed up for only one follow-up appointment had
the steepest rate of weight regain over the next 30 months,
regaining 82% of the weight they had lost. Participants who
showed up for two to four follow-up appointments regained
59% of the lost weight. In addition, a survey of individuals
who had participated in a commercial weight loss program
found that individuals who responded to the survey had lost
significantly more weight than those who did not respond
(Grodstein, Levine, Spencer, Colditz, & Stampfer, 1996).
One study with a high follow-up rate enticed partici-
pants back to the study by offering further diet services
(Graham, Taylor, Hovell, & Siegel, 1983). Only 23% of
participants responded to requests to return for further
assessments when those requests were made with a stan-
dard letter and phone call. But when researchers offered an
inexpensive follow-up class, an additional 60% of partici-
pants agreed to return, and 17% more agreed to return after
being offered home weights and a free class. This pattern of
return suggests that the recruitment practices used by
nearly all other studies (a letter and a phone call) may
inadvertently lose participants who feel that they still need
further weight loss services. Giving participants the sense
that it is fine to return for additional follow-ups even if they
regained significant amounts of weight may help to in-
crease follow-up rates and reduce bias.
It is difficult to compare studies based on their fol-
low-up rates, because studies reported and computed these
rates in different ways. Ideally, these rates would be com-
puted by dividing the number of participants in the fol-
low-up by the total number of participants in the original
diet (as reported in Table 1). Few, if any, studies, however,
compute their follow-up rate that way. Most studies sub-
tract various subgroups of participants from the total num-
ber of participants in the original study, thereby reducing
the denominator of this equation and increasing the re-
ported follow-up rate.
The subset of participants typically subtracted from
the overall total includes participants who have died since
the study ended and participants for whom researchers
could not locate a valid phone number or address. Attrition
for those reasons is considered random by most research-
ers, but it may not be. Because being obese is linked to
health outcomes, participants who have died may have
been more likely than other participants to have regained
their lost weight. In studies in which participants know
there are long-term follow-ups, being difficult to locate is
not necessarily a random event. Participants with poor
outcomes may not bother continuing to update study per-
sonnel on their whereabouts.
Even more problematic is that most researchers also
subtract additional categories of participants from their
original study totals (and their data analyses), and exclud-
ing these categories does not just make the follow-up rate
appear higher than it actually was, but it also typically
makes the diet appear more successful than it was. These
additional categories of exclusions include participants
who did not lose sufficient amounts of weight during the
study, participants who left substantial portions of ques-
tionnaires blank, participants who had participated in a
similar diet before, participants who refused to participate
in earlier follow-ups for the study, participants who did not
return calls, and participants who had gastric bypass sur-
geries (or other types of surgery) to induce weight loss
subsequent to the study. One study reported excluding two
participants from analyses because “inclusion of the two
patients strongly skewed the results against weight loss
maintenance” (Walsh & Flynn, 1995, p. 232).
These types of exclusions can lead to follow-up
reports on fractured samples. For example, one study
enrolled 426 participants in a diet program (Anderson,
Vichitbandra, Qian, & Kryscio, 1999) and then excluded
all but 154 participants from analysis for a variety of the
reasons reported above. Researchers obtained follow-up
weights for 112 of those 154 participants at their first time
point and therefore reported a follow-up rate of 73%, even
though only 26% of the original participants were included
in the follow-up. In addition, the article is a long-term
follow-up study, but the final four follow-up points only
include from 15 to 42 participants each, a tiny fraction of
the original sample size.
Which categories of participants it is appropriate to
exclude from study totals is, of course, a judgment call, but
it is important to remember that all of these exclusions
likely make weight loss maintenance appear more success-
ful than it is. It is worth noting that although studies find
numerous reasons to exclude participants who might make
the diet look ineffective, it does not appear that any studies
exclude participants who might inappropriately make the
diet look effective. For example, we could not locate any
studies that excluded participants who had a history of
stable weight before a single recent episode of weight gain,
perhaps after a pregnancy or an episode of clinical depres-
Barbra
Samuels
226 April 2007
American Psychologist
sion. These individuals, whose weights are higher than
their long-standing typical weight, are thought to have an
easier time maintaining weight loss after a diet.
Self-reports of weight. Another reason why
the results from the 14 long-term diet studies are likely
biased toward overestimating the effectiveness of the diets
is that a substantial percentage of the participants in these
studies self-reported their weight (by mail or phone) in-
stead of being weighed at the lab (see Table 1). Researchers
generally acknowledge that the most accurate way to assess
individuals’ weight is to measure it with a scale in the
laboratory. Because many participants are unable or un-
willing to come back to the lab, it is not usually possible for
researchers to measure each participant’s weight.
In these studies, 56% of participants self-reported
their weight. The percentage of self-reported weights varies
significantly across the studies, with the larger studies
tending to have higher self-report rates than the smaller
studies. In three of the studies, including three of the four
largest studies, 100% of the participants self-reported their
weight. Self-report rates for the remaining 10 studies
ranged from 0% (in 5 studies with small sample sizes) to
63%. For some of these studies, researchers tried to correct
for self-reporting bias by adding 2.3 kg (5 lb) to each
participant’s weight. It is not clear if this is an adequate
correction.
There has been a considerable amount of research
comparing individuals’ self-reported weights to their scale-
measured weight, but most of that work was not conducted
with obese individuals or with individuals who were par-
ticipating in weight loss programs. A meta-analysis of 15
studies comparing individuals’ self-reported weight with
their scale-measured weight located only two studies of
participants in weight loss programs that reported sufficient
information to be included in the meta-analysis (Bowman
& DeLucia, 1992). Participants in the 15 studies signifi-
cantly underestimated their weight by approximately 2.1 kg
(4.6 lb). More extreme bias (underestimates of 3.7 kg [8.2
lb]) was found when considering just the studies of indi-
viduals in weight loss programs, although these conclu-
sions should be considered tentative as there were only two
such studies. Nevertheless, it is important for researchers to
use scale-measured weights as often as possible and to be
aware that the use of self-reported weights will bias studies
toward making diets look more effective than they are.
Confounding diet and exercise. Effects of
dieting are confounded with effects of exercising in many
long-term follow-ups of diet studies. Individuals on diets
should exercise, but if the goal is to evaluate the effects of
restricting calorie intake—not the effects of exercise— on
subsequent weight patterns, the occurrence of exercise be-
comes a methodological problem. This confound is partic-
ularly significant because correlational studies consistently
find that individuals who reported the most exercise also
had the best weight loss maintenance (reviewed in Fo-
gelholm & Kukkonen-Harjula, 2000; Wing, 1999).
Exercise has also been shown to improve the mainte-
nance of weight loss in two meta-analyses of controlled
trials in which participants were randomly assigned to diet
and exercise or just to diet (Fogelholm & Kukkonen-
Harjula, 2000; Wing, 1999).
In one study, for example, participants were randomly
assigned to a diet-only, exercise-only, or diet-plus-exercise
intervention for one year (Skender et al., 1996). All partic-
ipants lost similar amounts of weight during the first year.
When participants were reassessed during the second year,
the diet-only participants averaged a follow-up weight that
was about 0.9 kg (1.9 lb) heavier than baseline, whereas the
groups that included exercise remained 2.5 kg (5.5 lb)
below baseline.
According to the National Weight Control Registry, a
longitudinal study of individuals who maintained a weight
loss of 13.6 kg (29.9 lb) for at least one year, 90% of its
participants used regular physical activity as a strategy to
maintain the loss (Klem, Wing, McGuire, Seagle, & Hill,
1997). Similar results were found in another sample of
individuals who maintained a substantial weight loss (Kay-
man, Bruvold, & Stern, 1990) and in a survey of subscrib-
ers to Consumer Reports (“The Truth About Dieting,”
2002). In fact, a survey of participants in a commercial diet
program found that exercise frequency was the strongest
predictor of weight loss maintenance (Grodstein et al.,
1996). If substantial percentages of participants in diet
studies are exercising, the diet will appear more effective
than it actually is.
Nine of the 14 studies with long-term follow-ups did
not report information on the exercise habits of participants
(see Table 1). Of the 5 studies that did report on exercise,
3 found that participants who exercised regularly main-
tained significantly greater weight loss than participants
who did not exercise. One study did not find a correlation
between a yes–no question about exercise and weight loss
maintenance, but it had a small sample size (N 26) that
Jason
Chatman
227April 2007
American Psychologist
may have precluded finding such a correlation (Murphy,
Bruce, & Williamson, 1985). The remaining study assigned
participants to weight loss programs that either included or
did not include an exercise component (Stalonas, Perri, &
Kerzner, 1984). No differences in the amount of lost weight
maintained were found between participants assigned to the
two types of programs, but it is important to note that
researchers did not compare the weight loss maintenance of
participants who actually engaged in exercise with partic-
ipants who did not. Overall, it seems likely that long-term
follow-ups of diet studies give overly optimistic views of
the success of such diets because participants who exercise
tend to show greater weight loss maintenance than partic-
ipants who simply diet.
Participation in additional diets. Another
factor that obscures the results of long-term diet studies is
that study participants often participate in additional diets
after the diet being assessed in the study ends but before the
long-term follow-up data are collected. Eleven of the 14
studies with long-term follow-ups reported some informa-
tion on additional dieting (see Table 1). Seven of these
studies reported the percentage of participants who said
they had been on additional diets, and these rates ranged
from 20% to 65% of participants. Three additional studies
asked participants how many other diets they had been on
since the original one and reported means of one to three
other diets. Finally, one study reported that 12% of the
participants lost more than 10 kg (22 lb) on other diets (but
did not report the prevalence of simply participating in
other diets; Pekkarinen & Mustajoki, 1997).
Participating in additional diets can make the original
diet look more effective than it was, because a consistent
outcome of diets is significant weight loss in the short term
(which—as we have shown—will later be regained).
8
In
one study, participants were asked to report what they
weighed when they started an additional diet, and after
taking this weight into account, the researchers concluded
that “failure to correct for the effects of additional therapy
would have resulted in significant overestimation of the
long term efficacy of this therapy” (Wadden et al., 1989, p.
42). Another study found that participants had lost an
average of 11.8 more kg (26 lb) on additional diets and
noted that participants did not diet during follow-up until
their weight exceeded their baseline weight (Foster et al.,
1996). A survey of participants in a commercial diet pro-
gram asked participants to report their maximum weight
since completing the diet. It found that 60% of participants
weighed more than their starting weight at some point in
the three years since the diet ended, even though only 40%
currently weighed more than their starting weight (Grod-
stein et al., 1996).
In sum, long-term diet studies without control groups
find little support for the effectiveness of dieting in leading
to sustained weight loss. From one third to two thirds of
participants in diets will weigh more four to five years after
the diet ends than they did before the diet began. This
conclusion comes from studies that are biased toward
showing successful weight loss maintenance by the four
factors described above and must be considered a conser-
vative estimate of the percentage of individuals for whom
dieting is counterproductive. The true number may well be
significantly higher.
Observational Studies: Type 2. Prospective
Studies Without Randomization
At any particular time, individuals are gaining, maintain-
ing, or losing weight (Klesges, Isbell, & Klesges, 1992).
Prospective nonrandomized studies can help determine the
effects of dieting on weight by tracking weight trajectories
over time for both dieters and nondieters. In these studies,
individuals’ weight and diet statuses are assessed at base-
line and then their weight is measured at certain follow-up
points. These studies do not randomly assign individuals to
diet or not diet, so causal statements cannot be made from
them, but they do allow for useful comparisons between
people who choose to diet and people who choose not to
diet. To date, however, few studies have used such designs
and controlled for potential confounding variables.
Of the 10 prospective studies we located, only 1 found
that dieting at baseline led to weight loss over time, 2 found
no relation between dieting and weight change, and 7 found
that dieting led to weight gain. In the 1 study that showed
dieting to be effective, 1,120 adults were weighed at base-
line and again 4 years later (French, Jeffery, & Murray,
1999). During the ensuing years, participants reported the
number of weeks during which they engaged in 17 different
weight loss behaviors. Although the majority of the behav-
iors (including participating in weight loss groups, eating
low-calorie diet foods, and eating fewer carbohydrates) did
not significantly predict weight change over the 4-year
period, reducing calories did. Cumulative duration of cal-
orie reduction (in weeks) predicted weight loss 4 years
later, after controlling for baseline weight.
Two studies found no relationship between dieting
and weight. One weighed a group of 24 dieters and non-
dieters daily for six weeks and then again six months later
(Heatherton, Polivy, & Herman, 1991). Although neither
group showed significant weight gain or loss at six months,
dieting status was a significantly better predictor of weight
variability over the six weeks of daily weight recordings
than was initial body weight. The short duration of the
study may have prevented significant weight changes from
occurring, and the small sample size may have made any
changes difficult to detect. A similar study used a larger
sample size (N 305) and a longer follow-up time (2.5
years), however, and showed no relationship between re-
straint status and weight change (Klesges, Klem, Epkins, &
Klesges, 1991), although self-reports of weight were used.
The remaining seven prospective studies each found
that dieting was related to weight gain over time, after
controlling for baseline weight. In one methodologically
rigorous study, researchers attempted to explore the long-
term effects of dieting on weight gain over 6 and 15 years
in a large cohort (N 7,729) of adult Finnish twins
8
Repeatedly losing and then regaining weight, called weight cycling,
is not recommended as a weight loss strategy.
228 April 2007
American Psychologist
(Korkeila, Rissanen, Kapro, Sorensen, & Koskenvuo,
1999). Overall, the authors found that attempts to lose
weight were related to future risk of major weight gain,
even after controlling for several potential confounding
variables. Specifically, dieting at baseline was a consistent
predictor of subsequent weight gain (of over 10 kg [22 lb])
at both follow-ups after adjusting for age, BMI, smoking,
alcohol use, education level, social class, marital status, and
energy expenditure at baseline.
The findings of Korkeila et al. (1999) are consistent
with several other prospective studies indicating that diet-
ing history is related to risk for future weight gain. For
example, French et al. (1994) examined the relationship
between dieting and exercise behaviors and changes in
body weight. They found that both men and women who
had participated in formal weight loss programs gained
significantly more weight over a two-year period than those
individuals who had not participated in such a program.
Among the 3,552 participants, this history of formal weight
loss attempts predicted weight gain, even after controlling
for baseline weight, dietary intake, physical activity, age,
education level, occupation, marital status, and smoking
status. Another prospective study examined a variety of
lifestyle factors and their relationship to changes in weight
over a four-year period in over 19,000 healthy older men
(Coakley, Rimm, Colditz, Kawachi, & Willett, 1998). One
of the two best predictors of weight gain over the four years
was having lost weight on a diet at some point during the
years prior to baseline, and this predictor remained signif-
icant even after controlling for baseline height and weight,
physical activity, television viewing, and eating habits.
Two studies prospectively examined the relationship
between dieting and weight change in large samples (N
14,972 and N 692, respectively) of adolescents (Field
et al., 2003; Stice, Cameron, Killen, Hayward, & Taylor,
1999). In the larger study, participants were followed for
three years, and dieters gained more weight during this
time than nondieters, controlling for an exhaustive set of
variables, including age, gender, BMI, calorie intake, and
physical activity. This weight gain was not explained by
increases in calorie or fat intake. In the smaller study of
adolescents (Stice et al., 1999), participants were followed
annually for four years and had an average increase in
weight of about 1.4 kg (3 lb). Participants who were ini-
tially overweight were no more susceptible to weight gain
than those who were underweight or normal weight at
baseline. There was a significantly higher increase in
weight and onset of obesity in participants who had prior
weight loss attempts, and participants who were dieting at
baseline showed increases in weight, controlling for their
baseline weight. Of the 589 female adolescents who were
not obese at baseline, 63 had become obese by the end of
the study. The occurrence of obesity, like weight gain in
general, was strongly associated with prior weight control
efforts. Among female adolescents who dieted, the risk for
obesity onset over the four years was over three times that
for nondieters.
The final two studies found suggestive evidence that
dieting leads to more weight gain over time than not
dieting. A study of 287 Caucasian adults found that base-
line restraint status (as measured with the Restraint Scale)
significantly predicted weight gain in women (but not men)
a year later, controlling for baseline weight, age, energy
intake, and physical activity levels (Klesges et al., 1992). A
small study of college students over the week surrounding
the Thanksgiving holiday found that dietary restraint pre-
dicted increased weight gain over the eight-day period,
despite predicting decreased calorie consumption (Klesges,
Klem, & Bene, 1989).
In sum, prospective nonrandomized studies do not
provide support for the effectiveness of diets in leading to
sustained weight loss. In only 1 of these 10 studies did
dieting prospectively predict weight loss, and in the major-
ity of studies dieting predicted weight gain.
Balancing Benefits and Harms
The final step of the GRADE system of evaluating evi-
dence involves an analysis of the benefits of the treatment
in relation to potential harms from the treatment. As we
have reviewed above, the benefits of dieting are minimal.
Sustained weight loss was only found in a small minority of
participants, whereas complete weight regain was found in
the majority. Beneficial health outcomes have not been
consistently or frequently demonstrated in the long term,
and very few studies were able to show clinically signifi-
cant health benefits that persisted after weight regain.
Health benefits from even small weight losses are
widely touted as reasons to diet (Institute of Medicine,
1995), and indeed many short-term randomized trials dem-
onstrate such benefits. For example, short-term weight loss
appears to be effective in improving glycemic control for
people with (or at risk for) Type 2 diabetes (Torgerson,
Hauptman, Boldrin, & Sjostrom, 2004; Williams & Kelley,
2000), for relief of osteoarthritis symptoms (Felson, Zhang,
Anthony, Naimark, & Anderson, 1992), and for reducing
hypertension (Schotte & Stunkard, 1990).
However, short-term studies of health benefits of
weight loss do not address the question of what happens
when the weight is regained. Three of the long-term ran-
domized studies that we reviewed found that some health
benefits persisted despite participants regaining much of
their lost weight (Diabetes Prevention Program Research
Group, 2002; Multiple Risk Factor Intervention Trial Re-
search Group, 1990; Stamler et al., 1987), but it is not clear
from these trials whether the potent effects of the interven-
tions were from dieting or from exercise, sodium/alcohol
reduction, or even increased antihypertensive medication
use. The other trials we reviewed did not find sustained
health benefits when weight was regained. It may be the
case, as has been suggested by others, that dieting may be
beneficial primarily for certain subgroups of obese individ-
uals with comorbid conditions (Lissner, Steen, & Brownell,
1992).
It is also possible that weight regain leads to health
problems of its own. An analysis of the benefits and harms
of dieting must consider the potential harms of weight
cycling. Weight cycling, the repeated loss and regain of
weight, is commonly observed in dieters (Brownell &
229April 2007
American Psychologist
Rodin, 1994; National Task Force on the Prevention and
Treatment of Obesity, 1994). There is evidence from large-
scale observational studies that weight cycling is linked to
increased all-cause mortality (Blair, Shaten, Brownell, Col-
lins, & Lissner, 1993; Lee & Paffenbarger, 1992) and to
increased mortality from cardiovascular disease (Hamm,
Shekelle, & Stamler, 1989). In addition, weight cycling is
associated with increased risk for myocardial infarction,
stroke, and diabetes (French et al., 1997), increased high-
density lipoprotein cholesterol (Olson et al., 2000), in-
creased systolic and diastolic blood pressure (Kajioka, Tsu-
zuku, Shimokata, & Sato, 2002), and even suppressed
immune function (Shade et al., 2004).
It has often been suggested that the harmful effects of
weight cycling result from unintentional weight loss (i.e.,
from smoking or illness) rather than from intentional diet-
ing (French & Jeffery, 1994; National Task Force on the
Prevention and Treatment of Obesity, 1994). However, at
least two large-scale studies that controlled for uninten-
tional weight loss still found that intentional weight loss is
linked to mortality risk (Andres, Muller, & Sorkin, 1993;
Pamuk, Williamson, Serdula, Madans, & Byers, 1993), and
the balance of evidence does seem to implicate intentional
weight loss in adverse health outcomes.
In sum, the potential benefits of dieting on long-term
weight outcomes are minimal, the potential benefits of
dieting on long-term health outcomes are not clearly or
consistently demonstrated, and the potential harms of
weight cycling, although not definitively demonstrated, are
a clear source of concern. The benefits of dieting are simply
too small and the potential harms of dieting are too large
for it to be recommended as a safe and effective treatment
for obesity.
Research Agenda
Further study is needed in three primary areas to address
the health problems associated with obesity. It is clear that
dieting does not lead to sustained weight loss in the ma-
jority of individuals, and additional studies of the effects of
dieting on weight are not needed. A call for more rigorous
diet studies seems unwarranted as it has been noted that
among diet studies, “greater methodological rigor seems to
be associated with poorer results” (Kramer et al., 1989, p.
126). We do not think further study of existing diets will
lead to a different assessment, nor do we think a new diet
formulation will appear that leads to more favorable out-
comes. Instead, we recommend that researchers conduct
long-term randomized studies on the effects of dieting on
health outcomes, with a specific focus on whether the
short-term health benefits of weight loss persist after the
weight is regained. Such studies should measure health
indicators, such as cholesterol levels, blood pressure, and
blood glucose, as well as illness outcomes, and should
make an effort to assess whether obese people in general
will benefit or whether only people with risk factors for
particular illnesses will benefit. These studies must make
every effort to minimize the biases that led to overly
optimistic reports of the success of diets (i.e., low fol-
low-up rates, self-reported weights, participation in addi-
tional diets, and confounds with exercise).
Second, although we do not recommend further study
of the effects of dieting on weight loss, it is still necessary
to explore the health consequences of weight regain. Be-
cause the majority of individuals who engage in diets tend
to regain most of their lost weight, no diet can be recom-
mended without considering the potential harms of weight
cycling. Research must continue to examine the effects of
weight cycling, and in particular this work must make a
focused effort to distinguish effects of intentional weight
loss from those of unintentional weight loss. In addition,
research on weight cycling must attempt to locate mecha-
nisms that link weight cycling to health outcomes. So far,
such efforts have had mixed success (Brownell & Rodin,
1994; National Task Force on the Prevention and Treat-
ment of Obesity, 1994).
Finally, as noted earlier, exercise may very well be the
potent factor leading to sustained weight loss, particularly
among participants in the National Weight Control Regis-
try (Klem, Wing, McGuire, Seagle, & Hill, 1997). A com-
prehensive review of the effects of exercise on health stated
that in addition to its effects on weight, exercise also has
been linked to positive health outcomes, including de-
creased mortality, decreased cardiovascular disease, de-
creased Type 2 diabetes, decreased hypertension, and in-
creased mental health (U.S. Department of Health and
Human Services, 1996). We therefore suggest that future
research focus on exercise as a treatment for obesity. Es-
pecially recommended are randomized, controlled trials
that compare exercise-only interventions to both diet-only
interventions and combined interventions so that the effects
of exercise can be distinguished from the effects of dieting.
Studies typically confound the effects of diet and exercise
by comparing diet-only interventions with combined diet-
plus-exercise interventions (for a review, see Avenell et al.,
2004). These studies cannot assess whether exercise alone
is as beneficial, or even more beneficial, than diet plus
exercise. In one study that was able to assess the unique
contribution of exercise by comparing participants as-
signed to diet-only, exercise-only, or a combined inter-
vention, the exercise-only group showed better long-
term weight loss maintenance than the combined group
(Skender et al., 1996). More studies with this type of design
are needed.
In the studies reviewed here, dieters were not able to
maintain their weight losses in the long term, and there was
not consistent evidence that the diets resulted in significant
improvements in their health. In the few cases in which
health benefits were shown, it could not be demonstrated
that they resulted from dieting, rather than exercise, med-
ication use, or other lifestyle changes. It appears that dieters
who manage to sustain a weight loss are the rare exception,
rather than the rule. Dieters who gain back more weight
than they lost may very well be the norm, rather than an
unlucky minority. If Medicare is to fund an obesity treat-
ment, it must lead to sustained improvements in weight and
health for the majority of individuals. It seems clear to us
that dieting does not.
230 April 2007
American Psychologist
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Context.— Nonpharmacologic interventions are frequently recommended for treatment of hypertension in the elderly, but there is a paucity of evidence from randomized controlled trials in support of this recommendation.Objective.— To determine whether weight loss or reduced sodium intake is effective in the treatment of older persons with hypertension.Design.— Randomized controlled trial.Participants.— A total of 875 men and women aged 60 to 80 years with systolic blood pressure lower than 145 mm Hg and diastolic blood pressure lower than 85 mm Hg while receiving treatment with a single antihypertensive medication.Setting.— Four academic health centers.Intervention.— The 585 obese participants were randomized to reduced sodium intake, weight loss, both, or usual care, and the 390 nonobese participants were randomized to reduced sodium intake or usual care. Withdrawal of antihypertensive medication was attempted after 3 months of intervention.Main Outcome Measure.— Diagnosis of high blood pressure at 1 or more follow-up visits, or treatment with antihypertensive medication, or a cardiovascular event during follow-up (range, 15-36 months; median, 29 months).Results.— The combined outcome measure was less frequent among those assigned vs not assigned to reduced sodium intake (relative hazard ratio, 0.69; 95% confidence interval [CI], 0.59-0.81; P<.001) and, in obese participants, among those assigned vs not assigned to weight loss (relative hazard ratio, 0.70; 95% CI, 0.57-0.87; P<.001). Relative to usual care, hazard ratios among the obese participants were 0.60 (95% CI, 0.45-0.80; P<.001) for reduced sodium intake alone, 0.64 (95% CI, 0.49-0.85; P=.002) for weight loss alone, and 0.47 (95% CI, 0.35-0.64; P<.001) for reduced sodium intake and weight loss combined. The frequency of cardiovascular events during follow-up was similar in each of the 6 treatment groups.Conclusion.— Reduced sodium intake and weight loss constitute a feasible, effective, and safe nonpharmacologic therapy of hypertension in older persons. Figures in this Article CLINICAL TRIALS have repeatedly demonstrated that antihypertensive drug therapy reduces the risk of stroke and coronary heart disease.1- 2 During the past 2 decades, these findings have been confirmed in trials restricted to older patients with hypertension.3- 4 Despite the proven benefits of antihypertensive medication, increasing interest in nonpharmacologic approaches to prevent and treat hypertension has been prompted by the knowledge that antihypertensive medication reduces rather than eliminates risk5; the potential for medication-related adverse effects,6 adverse events,7 and biochemical changes8; the high cost of many antihypertensive medications9; and the fact that observational and experimental studies have demonstrated a strong relationship between nutrition and blood pressure (BP).10 Clinical trials have demonstrated that weight loss and sodium reduction are effective in the treatment of middle-aged patients with hypertension.11 These interventions are also recommended for the treatment of hypertension in older persons.4 Observational data support the latter approach,12 but the experimental basis for the recommendation is limited.13 With this in mind, we conducted the Trial of Nonpharmacologic Interventions in the Elderly (TONE) to determine the feasibility, efficacy, and safety of sodium reduction and weight loss in older persons with hypertension.
Article
• Compared the relative effectiveness of exercise and eating habit change individually and in combination for weight loss and physical conditioning. 44 female volunteers aged 17–46 yrs were randomly assigned to 1 of 4 groups: exercise, eating habits, combination, and delay-of-treatment control. Each group met for 8 1-hr sessions. Ss were assessed at pretreatment, posttreatment, and follow-up using measures of weight, physical fitness, and personal adjustment. After the 1 8-wk period, the control group was treated using the same procedures as employed for the combination group. Results indicate significant improvement for all treatment groups in comparison with the delay-of-treatment control on body weight and most measures of physical fitness and personal adjustment. Groups who exercised showed the most improvement in physical fitness. The combination group demonstrated the most improvement in weight and body circumference. At 8-wk follow-up, only the combination group continued to lose weight. Once treated, the delay-of-treatment control group demonstrated results similar to those of the combination group. Results suggest the necessity of combining exercise and eating habit change in dealing with obesity. (24 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved) • Compared the relative effectiveness of exercise and eating habit change individually and in combination for weight loss and physical conditioning. 44 female volunteers aged 17–46 yrs were randomly assigned to 1 of 4 groups: exercise, eating habits, combination, and delay-of-treatment control. Each group met for 8 1-hr sessions. Ss were assessed at pretreatment, posttreatment, and follow-up using measures of weight, physical fitness, and personal adjustment. After the 1 8-wk period, the control group was treated using the same procedures as employed for the combination group. Results indicate significant improvement for all treatment groups in comparison with the delay-of-treatment control on body weight and most measures of physical fitness and personal adjustment. Groups who exercised showed the most improvement in physical fitness. The combination group demonstrated the most improvement in weight and body circumference. At 8-wk follow-up, only the combination group continued to lose weight. Once treated, the delay-of-treatment control group demonstrated results similar to those of the combination group. Results suggest the necessity of combining exercise and eating habit change in dealing with obesity. (24 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
The Multiple Risk Factor Intervention Trial was a primary prevention trial to test the effect of multifactor intervention on coronary heart disease mortality in high-risk men who were randomly assigned to special intervention (n = 6428) or to their usual sources of health care (n = 6438). As previously reported, after 6 to 8 years of intervention, mortality from coronary heart disease and from all causes did not differ significantly between men assigned to special intervention and men assigned to their usual sources of health care. This report describes the mortality findings after 10.5 years (an average of 3.8 years after the end of intervention). Mortality rates were lower for men who received special intervention than for men who received their usual care by 10.6% for coronary heart disease and by 7.7% for all causes. Differences in mortality rates were substantially larger after the end of intervention than observed to that point. Differences in mortality rates after 10.5 years were primarily due to a 24% reduction in the death rate from acute myocardial infarction in men receiving special intervention compared with men receiving their usual care. As before, mortality differences between special intervention and usual care varied according to the presence of resting electrocardiographic abnormalities. These data suggest that multiple risk factor intervention confers a mortality benefit in middle-aged men over a period of about 10 years.
Article
The debate over the ability of researchers to substitute self-reports for measured weights is not settled. Studies conducted to date on the self-reports of weight have not provided a clear conclusion as to whether self-reports of weight are valid. The purpose of the present study was to organize and integrate the conflicting findings utilizing the statistical methods of meta-analysis (Hedges & Olkin, 1985). Data were analyzed by two methods of constructing effect sizes for the total sample, by sex of subject, and by type of population. Bias was found to be a significant component of self-reported weight for all groups. Discrepancies between self-report and true weight are reported for all groups, including estimations in pounds. Self-reported weight is concluded to be sufficiently accurate for epidemiological groups but not in clinical weight-loss subjects pools. Recommendations for future research and practice are suggested.
Article
OBJECTIVES We undertook an analysis of weight cycling, coronary risk factors and angiographic coronary artery disease (CAD) in women.BACKGROUND The effect of weight cycling on cardiovascular mortality and morbidity is controversial, and the impact of weight cycling on cardiovascular risk factors is unclear.METHODS This is a cross-sectional population study of 485 women with coronary risk factors undergoing coronary angiography for evaluation of suspected myocardial ischemia enrolled in the Women’s Ischemia Syndrome Evaluation (WISE). Reported lifetime weight cycling—defined as voluntary weight loss of at least 10 lbs at least 3 times—coronary risk factors including core laboratory determined blood lipoproteins and CAD, as determined by a core angiographic laboratory, are the main outcome measures.RESULTSOverall, 27% of women reported weight cycling—19% cycled 10 to 19 lbs, 6% cycled 20 to 49 lbs, and 2% cycled 50+ lbs. Reported weight cycling was associated with 7% lower high-density lipoprotein cholesterol (HDL-C) levels in women (p = 0.01). The HDL-C effect was directly related to the amount of weight cycled with women who lost ≥50 lbs/cycle having HDL-C levels 27% lower than noncyclers (p = 0.0025). This finding was independent of other HDL-C modulators, including estrogen status, physical activity level, alcohol intake, body mass index, diabetes, beta-blocker use, cigarette smoking and race. Weight cycling was not associated with an increased prevalence of CAD in this population.CONCLUSIONS Weight cycling is associated with lower HDL-C in women of a magnitude that is known to be associated with an increased risk of cardiac events as demonstrated in prior clinical trials.
Article
• A total of 841 healthy men and women aged 25 to 49 years, with diastolic blood pressures of 78 to 89 mm Hg, were randomly assigned to a control treatment group (no dietary counseling) or to one of four dietary counseling treatment groups (reduced calories, reduced sodium, reduced sodium and calories, or reduced sodium and increased potassium). Participants were followed for a 3-year period to assess the effect of dietary changes on blood pressure. After 6 months, counseling had resulted in a net (of control) mean overnight urinary sodium reduction of 13%, a potassium increase of 8%, and a decrease in mean body weight of 7%. At 3 years, the sodium and weight reductions were 10% and 4%, respectively; the potassium change was nil. All four dietary counseling treatment groups had lower mean blood pressures than the control group. The largest net reduction in blood pressure occurred in the calorie group: diastolic pressure was 2.8 mm Hg and 1.8 mm Hg and systolic pressure, 5.1 mm Hg and 2.4 mm Hg at 6 months and 3 years, respectively. All four dietary counseling treatment groups experienced fewer hypertensive events; significantly fewer occurred in the sodium groups. The beneficial effects on blood pressure achieved in this trial have implications for the prevention of cardiovascular disease through dietary reduction of calories and sodium. (Arch Intern Med. 1990;150:153-162)
Article
This article reviews the efficacy of strategies designed to improve the maintenance of treatment effects in the long-term management of obesity. Included are the results from controlled trials that evaluated strategies such as extended therapy, relapse prevention training, monetary incentives, food provision, and peer support as well as the use of very-low-calorie diets and phar-macotherapy. Improved maintenance of weight loss was observed in behavior therapy extended beyond 6 months and in long-term pharmacotherapy (dexfenfl-uramine or the combination of fenfluramine + phentermine) used in conjunction with behavior therapy or dietary counseling. Following the termination of long-term therapy, a regaining of weight was observed across all treatment modalities. These findings are discussed in terms of a “continuous-care” model of obesity management.