Diets reviewed and compared

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Hi All,

There is in JAMA a page dedicated to highlighting

the articles that may be of interest to readers of

JAMA. The readers tend to be clinicians, but the

articles of general interest as well can be found

in the page.

The ones I found that might be of interest to us

are below, with a follow-up on the reports of

yesterday regarding the Ann Internal Med reports

of the same issue: diets that may or may not be

effective in losing weight via or not calorie

restriction.

JAMA, January 5, 2005—Vol 293, No. 1 7

THISWEEK IN JAMA

JANUARY 5, 2005

A Piece of My Mind

" Mrs Smyth ...made it very clear to

me that if she ever stopped breathing,

she wanted no `so-called resuscita-tion.' "

From " The Octogenarian's

Plan. " SEE PAGE 15

Magnesium and Colorectal Cancer Risk

In a prospective study of women, mag-nesium

intake was inversely associated

with colorectal cancer risk.

SEE PAGE 86

Popular Diets, Weight Loss, and Cardiac Risk

Popular diets promise weight loss and disease risk reduction, but

data to support their

efficacy and health effects are limited. Dansinger and colleagues

assessed adherence and

1-year changes in baseline weight and cardiac risk factors in

overweight and obese

patients who were randomly assigned to 1 of 4 diets (Atkins, Zone,

Weight Watchers,

and Ornish), with varying nutrient composition. Adherence to the

assigned diets was

low. Modest weight change from baseline was associated with diet

adherence, not diet

type, and participants adhering to their assigned diet achieved

comparable, modest

improvements in several cardiac risk factors. In an editorial, Eckel

discusses the chal-lenges

of helping patients achieve and sustain a lower weight.

SEE PAGE 43 AND EDITORIAL ON PAGE 96

Quality of Life in Overweight and Obese Children

Previous studies have documented lower health-related quality of

life (QOL) in selected

samples of overweight and obese children, but population-based data

are

lacking. Wil-liams

and colleagues assessed health-related QOL in a representative sample

of Austra-lian

children, 9 to 12 years of age. They found that health-related QOL

declined with

increasing weight, particularly in measures of physical and social

functioning. Measures

of emotional and school function did not differ significantly across

weight categories.

SEE PAGE 70

And now below is the article after the review

for the diet program evaluations.

More Scrutiny for Dietary Supplements?

Hampton, PhD

JAMA, January 5, 2005—Vol 293, No. 1 27, 96-97

IN AN ATTEMPT TO TIGHTEN THE REINS

over control of dietary supple-ments,

the US Food and Drug Ad-ministration

(FDA) has announced sev-eral

regulatory initiatives. The actions

come following criticism that the gov-ernment

has reacted too slowly to the

dangers posed by supplements such as

ephedra and androstenedione, both of

which were taken off the market ear-lier

this year.

The new initiatives include a regula-tory

strategy designed to further imple-ment

the Dietary Supplement Health and

Education Act of 1994 (DSHEA), an

open public meeting, and a draft guid-ance

document for industry. Passage of

DSHEA allowed dietary supplements—

defined by Congress as products that

contain ingredients including vitamins,

minerals, herbs or other botanicals,

amino acids, and substances such as en-zymes,

organ tissues, glandulars, and me-tabolites—

to be sold over the counter

with little oversight unless the FDA could

demonstrate a product posed a clear dan-ger

to public health.

" With this strategy, we will now have

a clear roadmap to share with the di-etary

supplement industry and at the

same time give consumers a higher level

of assurance about the safety of di-etary

supplement products and the

truthfulness of their labeling, " said FDA

Acting Commissioner Lester Craw-ford,

DVM, PhD, during the annual

conference of the Council for Respon-sible

Nutrition, held in Lansdowne, Va.

But critics of the current lack of over-sight

of dietary supplements say that

while the effort is a worthwhile one, the

agency continues to operate in a reac-tionary

mode so that unsafe products

will remain on the market for ex-tended

periods before any enforce-ment

action is taken.

IDENTIFYING SAFETY CONCERNS

As part of its plan, the FDA is enlisting

the help of other federal partners, such

as the National Institutes of Health Of-fice

of Dietary Supplements and Na-tional

Center for Complementary and

Alternative Medicine and the National

Toxicology Program in the Depart-ment

of Health and Human Services, to

make safety decisions about dietary

supplements. Officials will evaluate

safety concerns by a process that starts

with identifying signs of possible safety

concerns. These can arise from adverse

event reports, international regulatory

actions, media reports, information from

consumer groups, and other sources. If

the agency finds enough evidence for ac-tion,

it could issue public health advi-sories,

require labeling changes, or make

a determination of unreasonable risk,

which could result in a ban of the sale

of a product.

Of particular importance to the new

initiative for monitoring dietary supple-ments

is a clarification of when a food

supplement ingredient is considered a

" new dietary ingredient " for which no-tification

and safety information must

be sent to the agency. (Under DSHEA,

dietary supplements do not need FDA

approval if the ingredients were mar-keted

in the United States before Oc-tober

15, 1994.)

The agency, which is seeking input

from the public on the issue, held an

open meeting on November 15 to hear

stakeholders' remarks regarding poten-tial

content and format requirements for

new dietary ingredient notification.

Critics, however, question whether

the new initiatives will add up to bet-ter

oversight of potentially unsafe

supplements. Marcus, MD, a

professor of medicine and immunol-ogy

at Baylor College of Medicine, in

Houston, Tex, and an author of sev-eral

published reports examining safety

issues relating to dietary supplements,

The FDA is embarking on several new

regulatory initiatives for dietary supplements,

but critics are skeptical that the effort will be

enough to keep unsafe products off the market.

said he believed that the FDA was not

making a genuine effort to reach out to

the public with this meeting. " I think

that this is an administration smoke

screen to head off meaningful revision

of DSHEA, " he said. " I think that the

publicity with ephedra is part of [the

reason for the meeting], as well as the

bills that have been introduced to make

adverse event reporting mandatory. " A

bipartisan group of senators have sub-mitted

legislation that would require

manufacturers to report serious ad-verse

events, but the bill has not moved

forward.

Currently, manufacturers are en-couraged

but not required to report to

the FDA adverse events from dietary

supplements. In contrast, mandatory re-porting

exists for prescription and over-the-

counter drugs. With the public's

safety at stake, the " FDA needs to go

to Congress and tell them that it wants

to have mandatory adverse event re-porting

authority, " said Ilene Ringel

Heller, senior staff attorney at the Cen-ter

for Science in the Public Interest, in

Washington, DC, a consumer advo-cacy

group. " And if they get [a require-ment

for mandatory monitoring], they

have to ensure that it works, " she noted.

" They have to make sure that they have

enough people to analyze the adverse

events. "

PRODUCT QUALITY

Ensuring product quality is another fo-cus

of the new initiatives. The FDA

hopes to establish industry-wide stan-dards

so that dietary supplements have

consistent purity, strength, and com-position.

In 2003, the agency pub-lished

a proposed rule on current good

manufacturing practice (GMP) require-ments

for dietary supplements; once

comment review is complete, it plans

to publish a final rule.

But Heller questions whether the rule

is likely to be effective. " It's an impor-tant

rule to have in place except that—

because of the way the dietary supple-ment

act is written—it's not going to

be as strong as it should be. " The agency

only has the authority to issue GMPs

based on those required for food prod-

ucts, not GMPs tailored to drug manu-facturers.

" So they're looking at a head

of lettuce vs a vial of drugs as what's ap-propriate, "

she said.

Marcus agrees with Heller's senti-ment.

" I think the GMPs are kind of a

joke when applied to these kinds of

complex products, " he said.

Another stated FDA goal is to find

ways to improve compliance and en-forcement.

Although Crawford stated

that the agency will continue to exer-cise

" due diligence " in its enforce-ment

activities, he does not anticipate

any immediate changes to the FDA's en-forcement

process. He added that FDA

officials believe that in general, most of

the dietary supplements already on the

market are safe. However, some supple-ments

may contain ingredients that are

pharmacologically active and may pose

potential health problems.

Crawford pointed to the agency's re-cent

enforcement actions against ephe-dra

and androstenedione as examples

of how the FDA can act to protect con-sumers

against such risks—although

critics say the actions came too late. Ear-lier

this year, the FDA published a rule

prohibiting the sale of dietary supple-ments

containing ephedra because they

present an unreasonable risk of illness

or injury, but that rule came only after

reports of at least 155 deaths linked to

the substance. The agency also sent

warning letters to companies asking

them to cease distributing dietary

supplements that contain androstene-dione.

In addition, consumer alerts were

issued warning the public of the dan-gers

of ephedra and androstenedione.

The FDA is also joining with the Fed-eral

Trade Commission to form a Di-etary

Supplement Enforcement Group

to combat health care fraud. As a part

of this effort, officials have conducted

several Internet searches to identify

fraudulent marketing of health care

products on the Web. Recently, the

agency sent warning letters to distribu-tors

making unsubstantiated claims

over the Internet for dietary supple-ments

promoted for weight loss. And

it sent a letter to major retailers of di-etary

supplements stating that prod-

ucts labeled with such unproven claims

are misbranded and enforcement ac-tion

may be taken against misbranded

products in their possession. Such ac-tions

could include seizing products as

well as pursuing injunctions or seek-ing

criminal sanctions against individu-als

who violate the law.

As the FDA continues monitoring and

evaluating dietary supplement claims, it

plans to create a draft guidance for in-dustry

that articulates a standard of

" competent and reliable scientific evi-dence "

that is consistent with the Fed-eral

Trade Commission's standard for

advertising. The guidance will address

what constitutes adequate scientific sub-stantiation

for structure and/or func-tion

claims as well as claims of benefit.

" We believe that the draft guidance will

allow manufacturers to provide truth-ful

information to consumers about the

benefits of dietary supplements, " said

Crawford. " We also believe that provid-ing

a standard for substantiation may

help to preserve consumer confidence

in these products, " he added.

RISKS REMAIN?

Heller said these initiatives are a step

in the right direction, but individuals

will remain unprotected from unsafe in-gredients

and unreliable claims. She

would like to see companies be re-quired

to obtain FDA authorization for

all health-related claims before they are

made. Currently, misleadingly labeled

products could remain on store shelves

for months or years before the agency

takes enforcement action, she said.

Marcus also sees problems with pub-lic

perception, including the fact that

the term dietary supplement is mislead-ing.

" Herbal medicine is not a dietary

supplement—it has no nutritional

value. It's a pharmacologically active

preparation, and it ought to be regu-lated

as such, " he said.

Details on ongoing FDA initiatives for

dietary supplements can be found at

http://www.cfsan.fda.gov/~dms/supplmnt.html.

Information on the re-cent

public meeting and follow-up com-ments

can be found at http://www.fda.gov/ohrms/dockets.

Comparison of the Atkins, Ornish, Weight

Watchers, and Zone Diets for Weight Loss

and Heart Disease Risk Reduction

A Randomized Trial

L. Dansinger, et al and Ernst J. Schaefer

JAMA. 2005;293:43-53

For editorial comment see p 96.

Context The scarcity of data addressing the health effects of

popular

diets is an im-portant

public health concern, especially since patients and physicians are

interested

in using popular diets as individualized eating strategies for

disease

prevention.

Objective To assess adherence rates and the effectiveness of 4

popular

diets (At-kins,

Zone, Weight Watchers, and Ornish) for weight loss and cardiac risk

factor re-duction.

Design, Setting, and Participants A single-center randomized trial at

an aca-demic

medical center in Boston, Mass, of overweight or obese (body mass

index: mean,

35; range, 27-42) adults aged 22 to 72 years with known hypertension,

dyslipidemia,

or fasting hyperglycemia. Participants were enrolled starting July

18,

2000, and ran-domized

to 4 popular diet groups until January 24, 2002.

Intervention A total of 160 participants were randomly assigned to

either Atkins

(carbohydrate restriction, n=40), Zone (macronutrient balance, n=40),

Weight Watch-ers

(calorie restriction, n=40), or Ornish (fat restriction, n=40) diet

groups. After 2 months

of maximum effort, participants selected their own levels of dietary

adherence.

Main Outcome Measures One-year changes in baseline weight and cardiac

risk

factors, and self-selected dietary adherence rates per self-report.

Results Assuming no change from baseline for participants who

discontinued the study,

mean (SD) weight loss at 1 year was 2.1 (4.8) kg for Atkins (21 [53%]

of 40 participants

completed, P=.009), 3.2 (6.0) kg for Zone (26 [65%] of 40 completed,

P=.002), 3.0

(4.9) kg for Weight Watchers (26 [65%] of 40 completed, P .001), and

3.3 (7.3) kg for

Ornish (20 [50%] of 40 completed, P=.007). Greater effects were

observed in study com-pleters.

Each diet significantly reduced the low-density

lipoprotein/high-density lipopro-tein

(HDL) cholesterol ratio by approximately 10% (all P .05), with no

significant effects

on blood pressure or glucose at 1 year. Amount of weight loss was

associated with self-reported

dietary adherence level (r=0.60; P .001) but not with diet type

(r=0.07; P=.40).

For each diet, decreasing levels of total/HDL cholesterol, C-reactive

protein, and insulin

were significantly associated with weight loss (mean r =0.36, 0.37,

and

0.39, respec-tively)

with no significant difference between diets (P=.48, P=.57, P=.31,

respectively).

Conclusions Each popular diet modestly reduced body weight and

several

cardiac

risk factors at 1 year. Overall dietary adherence rates were low,

although increased

adherence was associated with greater weight loss and cardiac risk

factor reductions

for each diet group.

POPULAR DIETS HAVE BECOME IN-creasingly

prevalent and con-troversial.

1 More than 1000 diet

books are now available,2 with

many popular ones departing substan-tially

from mainstream medical ad-vice.

3 Cover stories for major news

magazines, televised debates, and cau-tionary

statements by prominent medi-cal

authorities 4,5 have fueled public in-terest

and concern regarding the

effectiveness and safety of such diets.6-8

Although some popular diets are

based on long-standing medical ad-vice

and recommend restriction of por-tion

sizes and calories (eg, Weight

Watchers),9 a broad spectrum of alter-natives

has evolved. Some plans mini-mize

carbohydrate intake without fat

restriction (eg, Atkins diet),10 many

modulate macronutrient balance and

glycemic load (eg, Zone diet),11 and oth-ers

restrict fat (eg, Ornish diet).12 Given

the growing obesity epidemic,13 many

patients and clinicians are interested in

using popular diets as individualized

eating strategies for disease preven-tion.

14 Unfortunately, data regarding the

relative benefits, risks, effectiveness, and

sustainability of popular diets have been

limited.15-25

We conducted a 1-year randomized

trial of the dietary component of the At-kins,

Zone, Weight Watchers, and Or-nish

plans, aiming to determine their

realistic clinical effectiveness and sus-tainability

for weight loss and cardiac

risk factor reduction. Of note, this study

only evaluated the dietary compo-nents

and did not include other spe-cific

components that may be unique

to each individual dietary program.

... RESULTS

Participant Characteristics

The 40 participants in each of the 4 diet

groups were well matched in terms of

baseline characteristics (TABLE 1). Age,

race, sex, body mass index, and meta-bolic

characteristics generally matched

thoseofthe overweightpopulationinthe

United States.13 Baseline characteristics

did not differ significantly between diet

groups and regression models adjust-ing

for these (eg, hyperglycemia, base-

line insulin levels) or other potentially

confounding variables such as time of

diet class demonstrated no confound-ing

effects.

Of the 160 participants, the mean

(SD) age was 49 (11) years (range,

22-72 years) and 81 were women (n=21

in Atkins, n=20 in Zone, n=23 in

Weight Watchers, n=17 in Ornish

groups; P=.90 for sex difference be-tween

diets). Compared with men,

women had significantly lower mean

baseline weight (93 vs 106 kg), waist

size (103 vs 114 cm), diastolic blood

pressure (74 vs 78 mm Hg), and tri-glyceride

levels (150 vs 188 mg/dL [1.7

vs 2.1 mmol/L]) (all P .05), and higher

mean levels of C-reactive protein (4.8

vs 3.3 mg/L) and HDL cholesterol (52

vs 41 mg/dL [1.35 vs 1.06 mmol/L]).

Women were also more likely to be

nonwhite (38% vs 11%).

Attrition and Adverse Effects

The number of participants who did not

complete the study at months 2, 6, and

12 were 34 (21%), 61 (38%), and 67

(42%), respectively. At 1 year, there was

a nonsignificant trend (P=.08) toward

a difference in discontinuation rates be-tween

the more extreme diets (48% for

Atkins and 50% for Ornish) and mod-erate

diets (35% for Zone and 35% for

Weight Watchers). Twenty-seven of 61

participants who discontinued before 6

months were evaluated at 2 months

(mean weight loss, 2.6 kg) and 10 of 67

participants who discontinued before 12

months were evaluated at 6 months

(mean weight loss, 1.3 kg). Individuals

who discontinued the study had less for-mal

education (P=.001) and lower base-line

diastolic blood pressure (74 vs 78

mm Hg, P=.02) than those who com-

pleted. The most common reasons cited

for discontinuation of the study were

that the assigned diet was too hard to fol-low

or not yielding enough weight loss.

We were unable to identify any diet-related

adverse event or serious ad-verse

effects during the study. We found

no evidence of clinically significant re-nal

impairment in any of the diet groups.

Dietary Intake and Adherence

Dietary intake according to an intent-to-

treat analysis of 3-day diet records is

shown in TABLE 2. At baseline, 147

(92%) of the participants submitted food

records. Mean total energy intake was

2059 calories daily, with 46.4%, 34.5%,

and 17.6% of calories derived, respec-tively,

from carbohydrate, fat, and pro-tein.

There were no significant caloric or

macronutrient differences between diet

groups at baseline. For each group, di-etary

adherence as assessed by diet re-cords

decreased progressively with time,

although the specifically targeted di-etary

parameters for each diet were sig-nificantly

different from baseline (all

P .01) at each time point, according to

both the primary and secondary analy-ses.

At 1 year, the mean caloric reduc-tions

from baseline were 138 for At-kins,

251 for Zone, 244 for Weight

Watchers, and 192 for Ornish groups (all

P .05, P=.70 between diets).

Group mean adherence scores accord-ing

to diet records and self-assessment

were highly associated for the duration

of the study (Pearson r=0.90; P .001).

As with diet records, adherence accord-ing

to self-report gradually decreased

over time, and to a similar extent in each

diet group (FIGURE 2). Nevertheless, ap-proximately

25% of participants in each

diet group sustained a mean adher-ence

level of at least 6 of 10, which ap-peared

to delineate a clinically mean-ingful

adherence level.

Weight Loss

According to the primary intent-to-treat

analysis (TABLE 3) and the sec-ondary

analysis that excluded missing

data (TABLE 4), all 4 diets resulted in

modest statistically significant weight

loss at 1 year, with no statistically sig-

nificant differences between diets

(P=.40). In each diet group, approxi-mately

25% of the initial participants

sustained a 1-year weight loss of more

than 5% of initial body weight and ap-proximately

10% of participants lost

more than 10% of body weight. Weight

reductions were highly associated with

waist size reductions for all diets (Pear-son

r=0.86 at 1 year; P .001), with no

significant difference between diets. In

women, mean (SD) body weight de-creased

by 2.4 (5.1) kg (2.5% change

from baseline) and waist size by 2.3

(4.5) cm, whereas in men body weight

decreased by 3.3 (6.4) kg (3.1% change

from baseline) and waist size by 3.1

(5.8) cm at 1 year (P =.30 for sex

differences).

In contrast with the absent associa-tion

between diet type and weight loss

(r =0.07; P=.40), we observed a strong

curvilinear association between self-reported

dietary adherence and weight

loss (r =0.60; P .001) that was almost

identical for each diet (FIGURE 3). Par-ticipants

in the top tertile of adherence

lost 7% of body weight on average.

Cardiac Risk Factors

According to the primary intent-to-treat

analysis (Table 3), all diets

achieved modest, although statisti-cally

significant, improvements in sev-eral

cardiac risk factors at 1 year. All

diets reduced mean LDL cholesterol lev-els

at 1 year, although this did not reach

statistical significance in the case of the

Atkins group (P=.07). All diets signifi-cantly

increased mean HDL choles-terol

levels, except in the Ornish diet

group (P=.60). The LDL/HDL ratio de-creased

approximately 10% in each diet

group (all P .05). No diet program sig-nificantly

altered triglycerides, blood

pressure, or fasting glucose at 1 year.

The lower carbohydrate diets (Atkins

and Zone) were more likely to reduce

triglycerides, diastolic blood pressure,

and insulin in the short term, al-though

the Atkins diet failed to signifi-cantly

reduce mean fasting insulin lev-els

at 1 year (P=.26). All the diets

reduced 1-year C-reactive protein lev-els

by approximately 15% to 20%, al-

though the reduction did not reach sta-tistical

significance in the case of the

Zone diet (P =.09). The secondary

analysis, which excluded missing data

(Table 4), demonstrated larger but oth-erwise

similar changes overall.

The amount of weight loss pre-dicted

the amount of improvement in

several cardiac risk factors (FIGURE 4).

For each diet, weight loss was signifi-cantly

associated with changes in total/

HDL cholesterol ratio (r =–0.36), C-reactive

protein (r=–0.37), and insulin

levels (r=–0.39), regardless of diet type

(P=.48, P=.57, P=.31, respectively, for

difference between diets). No diet sig-nificantly

worsened any cardiac risk fac-tor

in association with weight loss or

dietary adherence at 1 year.

Exercise and Medication Use

Exercise levels, according to partici-pant

report (vigorous, moderate, mild,

minimal), were modestly increased

from baseline throughout the trial (all

P .05), and to a similar extent for each

diet group (P=.70 between diets). At

1 year, the numbers of participants with

increased and decreased exercise lev-els

from baseline were 11 and 2 for At-kins,

10 and 7 for Zone, 14 and 3 for

Weight Watchers, and 8 and 3 for Or-nish

groups, respectively. The amount

of weight loss was associated with

changes in exercise level (r =0.27;

P=.001), with no significant differ-ences

between diets (P=.70). After ac-counting

for dietary adherence, there

was no significant association be-

tween change in exercise and change

in body weight or any cardiac risk fac-tor

at 1 year.

The number of prescription medi-cations

(mean, 2.4) did not signifi-cantly

change in the 126 participants

who remained in the study for at least

2 months. The net change in total num-ber

of prescription medications for the

Atkins, Zone, Weight Watchers, and

Ornish groups was +7, –4, –7, and +5,

respectively (P=.16 for difference be-tween

diets). Adjusting for changes in

baseline medication use did not mate-rially

affect the study outcomes. For ex-ample,

4 to 7 participants in each group

were initially taking cholesterol-lowering

medication, which was dis-continued

by 1 individual in the Zone

group and initiated during the study by

primary care physicians for 1 each in

the Atkins and Weight Watchers groups

and for 3 in the Zone group. When in-dividuals

who initiated cholesterol-lowering

medication were excluded

from the intent-to-treat analysis, the re-ductions

in LDL/HDL cholesterol ra-tios

observed with each diet remained

statistically significant, and associa-tions

between weight loss and lipid

changes were unchanged or slightly

stronger.

COMMENT

In our randomized trial, we found that

a variety of popular diets can reduce

weight and several cardiac risk factors

under realistic clinical conditions, but

only for the minority of individuals who

can sustain a high dietary adherence

level. Despite a substantial percentage

of participants who could sustain mean-ingful

adherence levels, no single diet

produced satisfactory adherence rates

and the progressively decreasing mean

adherence scores were practically iden-tical

among the 4 diets. The higher dis-continuation

rates for the Atkins and

Ornish diet groups suggest many indi-viduals

found these diets to be too ex-treme.

To optimally manage a na-tional

epidemic of excess body weight 33

and associated cardiac risk factors, prac-tical

techniques to increase dietary ad-herence

rates are urgently needed.

One way to improve dietary adher-ence

rates in clinical practice may be to

use a broad spectrum of diet options, to

bettermatch individualpatientfoodpref-erences,

lifestyles, andcardiovascularrisk

profiles. Participants in our study were

not allowed to choose their dietary as-signment;

however, we suspect adher-ence

rates and clinical improvements

would have been better if participants

had been able to freely select from the 4

diet options. Our findings challenge the

concept that 1 type of diet is best for ev-erybody

and that alternative diets can be

disregarded. Likewise, our findings do

not support the notion that very low car-bohydrate

diets are better than stan-dard

diets, despite recent evidence to the

contrary.17,22,23,25

Our results support a growing body

of research suggesting that carbohy-drate

restriction and saturated fat re-striction

have different effects on car-diovascular

risk profiles. Low

carbohydrate diets consistently in-crease

HDL cholesterol,17,20 and low–

saturated fat diets consistently de-crease

LDL cholesterol levels.34 Low

carbohydrate diets have typically been

more effective for short-term reduc-tion

of serum triglycerides, glucose,

and/or insulin.17,19,22,23,35,36 These find-ings

may suggest to some clinicians that

the degree to which a patient exhibits

features of the metabolic syndrome

might guide the degree of carbohy-drate

restriction to recommend. In the

long run, however, sustained adher-ence

to a diet rather than diet type was

the key predictor of weight loss and car-diac

risk factor reduction in our study.

The clinical significance of diet-induced

changes in HDL cholesterol is

unclear. High-carbohydrate/low-fat

diets typically reduce or fail to in-crease

HDL cholesterol levels, but in-sufficient

data exist to determine

whether this is harmful or benign in

terms of cardiac events or atheroscle-rosis

progression.34,37,38 Similarly, the in-crease

in HDL cholesterol associated

with low-carbohydrate/high-fat diets is

of unclear benefit due to a lack of rel-evant

dietary intervention trials. In-creased

saturated fat intake may poten-tially

contribute to HDL cholesterol

increases in the case of the Atkins diet,

although we observed no such associa-tion

between changes in HDL choles-terol

and saturated fat in our study. The

reduction in LDL/HDL cholesterol ra-tio

observed for each diet is suggestive

but not conclusive of net beneficial ef-fects

on lipid profiles. Clearly, the car-diovascular

and other health effects of

dietary alternatives require additional

study.

By design, our study provided a lim-ited

amount of support beyond the ini-tial

2 months to estimate the real-world

effectiveness and sustainability

of the diets when a long-term support

system was lacking. A benefit of this ap-proach

was the enhanced ability to

demonstrate a dose-response relation-ship

between dietary adherence lev-els,

weight loss, and clinical benefits.

A drawback is that this approach is

poorly suited to determine the effects

of each diet in highly adherent indi-viduals.

Research studies and clinical

programs that aim to maximize adher-ence

to dietary and other lifestyle rec-ommendations

are known to obtain

greater clinical benefits.39,40

Our study has several limitations.

Our study was designed to identify the

clinical strengths and weaknesses of

each diet under identical conditions but

was not necessarily designed to iden-tify

a " best diet. " If one diet produces

more weight loss or cardiac risk reduc-tion

than the other diets do, a much

larger sample size would probably be

required to detect such differences un-der

similar conditions. Our study had

a relatively high rate of attrition, which

confounds the interpretation of the re-sults

because the magnitude of the re-sults

depends on the accuracy of an un-verifiable

assumption. The assumption

that participants who discontinued the

study were unchanged from baseline is

reasonable but imprecise.41 Neverthe-less,

we believe our general findings are

reasonably valid based on 3 observa-tions:

participants who discontinued

were reasonably similar to the other par-ticipants

from a demographic and clini-cal

perspective, the participants who

discontinued had evidence of weight

loss rather than weight gain before dis-continuing,

and we obtained meaning-ful

(albeit modest) results despite a

rather conservative approach to han-dling

the missing data. Our study was

limited in its ability to exclude long-term

safety risks or occasional danger-ous

adverse effects resulting from the

diets, even though we found no short-term

safety risks in our study. Finally,

the measurements of dietary intake and

adherence relied on self-reporting and

are therefore subjective.

In conclusion, poor sustainability and

adherence rates resulted in modest

weight loss and cardiac risk factor re-ductions

for each diet group as a whole.

Cardiac risk factor reductions were as-sociated

with weight loss regardless of

diet type, underscoring the concept that

adherence level rather than diet type was

the key determinant of clinical ben-efits.

Cardiovascular outcomes studies

would be appropriate to further inves-tigate

the potential health effects of these

diets. More research is also needed to

identify practical techniques to in-crease

dietary adherence, including tech-niques

to match individuals with the di-ets

best suited to their food preferences,

lifestyle, and medical conditions.

Cheers, Alan Pater

[Guest guest]

Hi folks:

Quite funny for us here really. From Al's post, near the end:

" Cardiac risk factor reductions were associated with weight loss

regardless of diet type, underscoring the concept that adherence

level rather than diet type was the key determinant of clinical

benefits. "

IMO *** WRONG CONCLUSION ***. Would not the following make more

sense? ................

" Cardiac risk factor reductions were associated with weight loss

regardless of diet type, underscoring the concept that ..... IT IS

SIMPLY THE LOSS OF WEIGHT, NOT THE MEANS BY WHICH IT IS LOST (within

reason), THAT IS OF OVERWHELMING IMPORTANCE. "

Evidently there are plenty of very knowledgeable people who haven't

figured out CR yet!

Rodney.

--- In , " old542000 " <apater@m...>

wrote:

>

> Hi All,

>

> There is in JAMA a page dedicated to highlighting

> the articles that may be of interest to readers of

> JAMA. The readers tend to be clinicians, but the

> articles of general interest as well can be found

> in the page.

> Popular Diets, Weight Loss, and Cardiac Risk

> Popular diets promise weight loss and disease risk reduction,

but

> data to support their

> efficacy and health effects are limited. Dansinger and colleagues

> assessed adherence and

> 1-year changes in baseline weight and cardiac risk factors in

> overweight and obese

> patients who were randomly assigned to 1 of 4 diets (Atkins, Zone,

> Weight Watchers,

> and Ornish), with varying nutrient composition. Adherence to the

> assigned diets was

> low. Modest weight change from baseline was associated with diet

> adherence, not diet

> type, and participants adhering to their assigned diet achieved

> comparable, modest

> improvements in several cardiac risk factors. In an editorial,

Eckel

> discusses the chal-lenges

> of helping patients achieve and sustain a lower weight.

....................................

> Comparison of the Atkins, Ornish, Weight

> Watchers, and Zone Diets for Weight Loss

> and Heart Disease Risk Reduction

> A Randomized Trial

> L. Dansinger, et al and Ernst J. Schaefer

> JAMA. 2005;293:43-53

>

> Context The scarcity of data addressing the health effects of

> popular

> diets is an im-portant

> public health concern, especially since patients and physicians are

> interested

> in using popular diets as individualized eating strategies for

> disease

> prevention.

> Objective To assess adherence rates and the effectiveness of 4

> popular

> diets (At-kins,

> Zone, Weight Watchers, and Ornish) for weight loss and cardiac risk

> factor re-duction.

> Design, Setting, and Participants A single-center randomized trial

at

> an aca-demic

> medical center in Boston, Mass, of overweight or obese (body mass

> index: mean,

> 35; range, 27-42) adults aged 22 to 72 years with known

hypertension,

> dyslipidemia,

> or fasting hyperglycemia. Participants were enrolled starting July

> 18,

> 2000, and ran-domized

> to 4 popular diet groups until January 24, 2002.

> Intervention A total of 160 participants were randomly assigned to

> either Atkins

> (carbohydrate restriction, n=40), Zone (macronutrient balance,

n=40),

> Weight Watch-ers

> (calorie restriction, n=40), or Ornish (fat restriction, n=40) diet

> groups. After 2 months

> of maximum effort, participants selected their own levels of

dietary

> adherence.

...........................

> Cardiac risk factor reductions were as-sociated

> with weight loss regardless of

> diet type, underscoring the concept that

> adherence level rather than diet type was

> the key determinant of clinical ben-efits.