CR versus exercise for weight loss

[Guest guest]

Hi All,

We exercise moderately and CR. However, the

combination may more extensively reduce weight.

http://tinyurl.com/4axhz data is used to show

the figure of the prominent effects of reduced

exercise but unchanged diet on obesity. This

may appear to downplay the role of diet, but the

remainder of the article does not reduce the

importance of a reduced calorie diet.

It should be emphasized that the exercise

accompanying CR is moderate. This may

be beneficial in terms of compensating the

loss of muscle tissue and bone loss.

The pdf is available for the not in Medline below.

ACSM'S HEALTH & FITNESS J, 8 (5) SEPT/OCT 2004 9-14

Which Is More Effective For Maintaining A Healthy Body

Weight: Diet or Exercise?

S. Pescatello, Stella Lucia Volpe, .

Bottom Line

In the few studies that directly compare the

effectiveness of diet versus exercise as weight loss

methods, the influence of exercise alone compared with

diet alone is modest. However, the energy deficit

imposed by diet in these studies was far greater than

that imposed by exercise. Current evidence indicates

that when diet and exercise are used in combination,

30 minutes/day of moderate intensity physical activity

coupled with caloric (500 to 1,000 kcal/day) and fat

(less than 30% of total energy intake) restriction are

sufficient for weight loss and associated health benefits.

For successful long-term weight loss maintenance,

even greater amounts of lifestyle physical activity are

recommended that should be supported by multimodal

strategies that include the following: 1) community-wide

campaigns, 2) point-of-contact strategies, 3)

comprehensive lifestyle modification programs, 4) social

support interventions in community settings, and

5) environmental supports and access combined with

informational outreach activities.

Learning Objective

To discuss the merits of diet, exercise, or both for achieving

and maintaining a healthy body weight.

Key words: Nutrition, Obesity, Physical Activity, Weight

Loss, Weight Management.

Approximately 97 million people in the United States

are overweight or obese (1), and the World Health

Organization has declared obesity a ``global

epidemic'' (2). The routine recommendations given to

people who have excess weight are to increase exercise levels

and reduce energy intake. Yet the millions of Americans

who try to exercise more and eat less often fail to lose their

excess weight, and even fewer sustain their original weight

loss (3). Hence, as a nation, America continues to get

heavier.

The purpose of this article is to deliberate the relative

importance of diet and exercise as strategies for maintaining

a healthy body weight. We acknowledge that both

strategies are essential to achieve this goal. Nonetheless, this

article is formatted as a debate in which the authors take

the position that diet or exercise makes the more significant

contribution to the obesity epidemic and its resolution

via attainment and maintenance of a healthy body weight

(this information was first presented as a Socratic debate at

the 2002 Annual Meeting of the New England Chapter

of ACSM, Providence, RI). Our intent with this format is

to challenge health and fitness professionals to ``think

out of the box'' regarding approaches that they can use to

enable overweight and obese clientele to achieve and

maintain a healthy body weight. To reinforce this message,

we will conclude by presenting the recommendations of

the American Dietetic Association (ADA) (4), ACSM (5),

and the Institute of Medicine (IOM) (6) for successful

long-term weight loss maintenance.

The Diet Perspective

Obese individuals try many approaches to lose weight,

including fad diets, exercise machines, and supplements,

some of which can be harmful. The risks associated with

fad diets and supplements often outweigh any benefits.

Thus it is a challenge for nutritionists and exercise

professionals to help people lose weight and then maintain

their weight loss, as it is for the many individuals

attempting to accomplish these goals. The etiology of

overweight and obesity is multifactorial; however, being

in a positive energy balance is the underlying cause, and

the one in which practitioners in the health related

fields can have significant impact. It is imperative that

individuals make dietary changes to lose weight or prevent

weight regain because it is overeating that has made a

significant contribution to the obesity epidemic.

Diet and a Healthy Body Weight

H. Lantz, Ph.D., et al. (7) reported that significant weight

loss was maintained after a 4-year hypo-energetic diet and

behavioral program in obese men and women (n = 113).

The study participants did not have any type of

obesity-related surgery, were not taking any medications

for weight loss, and did not participate in a regular exercise

program. On average, they lost 6 to 8 kg. Further, those

who completed the 4-year program (n = 55) maintained a

3 kg weight loss for 8 years after completion of the program.

In the Women's Health Trial: Feasibility Study in

Minority Populations (8), a long-term, low-fat, dietary

intervention resulted in significant decreases in body weight

without any major efforts to reduce energy among older

white, African-American, and Hispanic women. Unlike

Dr. Lantz et al. (7), these researchers found that major

alterations in body weight occurred with minor changes

in diet. Diets of this type are a more practical approach

for weight loss in free-living populations.

Diet not only plays a major role in weight loss but also

positively impacts blood lipids and glucose. S. Ash, Ph.D.,

et al. (9) determined the efficacy of three different types

of dietary treatment for weight management and blood

glucose control in 51 overweight men with type 2 diabetes

mellitus. Their study was a 12-week intervention that

included three iso-energetic dietary groups: 1) intermittent

energy restriction, 2) pre-portioned meals, and 3)

self-selected meals. Each group had weekly contact with a

registered dietitian. For all groups, the 12-week dietary

intervention resulted in a mean decrease in energy intake

(564 ± 665 kcal/day) and significant declines in body weight

(6.4 ± 4.6 kg), waist circumference (8.1 ± 4.6 cm),

percentage body fat (1.9 ± 1.5%), glycosylated hemoglobin

levels (HbA1c; a measure of long-term glucose control,

1.0 ± 1.4%), and triglycerides (0.3 ± 0.6 mmol/L).

Unfortunately, of the 27 individuals who returned for the

18-month follow-up visit, none of these improvements in

body composition or metabolic health was maintained.

The authors concluded that an energy intake of

approximately 1,400 to 1,700 kcal/day was effective in

attaining a 6% weight loss and improving glucose control

in men with type 2 diabetes mellitus. Dr. Ash et al. (9)

proposed ``it was the intensive weekly contact with a

health professional in combination with moderate energy

restriction that facilitated the successful short term

results seen.''

In summary:

Obesity has become a ``global epidemic,'' and the

increased consumption of energy has made a major

contribution to this epidemic. For example, during

1971 through 2000, average energy intake significantly

increased (P < 0.01) from 2,450 kcal/day to

2,618 kcal/day (10).

If individuals can change their dietary intake slightly by

decreasing energy intake or fat intake, prevention of

weight gain or weight loss will be achieved.

There will be even greater rates of prevention of weight

gain with diet if some type of behavioral support system

is made available.

The Physical Activity Perspective

Diets are synonymous with restricted energy intake and

skipped meals to ``voluntarily'' lose weight. Diets are seldom

voluntary and represent temporary short-term solutions

to being overweight, so it is not surprising that they have

failed as an approach to reverse the obesity epidemic. This

portion of our deliberation presents the physical activity

perspective because it is the critical component for

long-term weight loss maintenance. Specifically, the physical

activity position conveys the significant contribution

physical inactivity has made to the global obesity epidemic

and its essential role in achieving and maintaining a healthy

body weight.

Adults lose weight when they decrease or reduce energy

intake and dietary fat content through diet and/or increase

energy expenditure through physical activity. Paradoxically,

decreases in caloric and fat intake have occurred along

side dramatic increases in the prevalence of obesity over the

past 25 years in the United States (11) and industrialized

countries worldwide (12). For example, in the United

Kingdom, the prevalence of obesity increased more than

150% between 1980 and 1995, while energy and fat intake

decreased over this same time period (Figure) (12). The

occurrence of escalating rates of obesity in the presence

of reduced energy and fat intake suggests declining energy

expenditure (as illustrated by the surrogate measures

of physical inactivity, e.g., television viewing and car

ownership, in the Figure) is the primary culprit for the

rising prevalence of overweight and obesity in industrialized

societies worldwide.

Physical Activity and a Healthy Body Weight

More than two thirds of Americans are overweight, and

not so coincidentally, approximately the same numbers of

Americans do not exercise regularly. A viable public health

strategy to thwart the obesity epidemic is to improve the

health of those with excess weight through increased

physical activity (1, 3, 4, 13). Physical activity results in

numerous health benefits with or without weight loss. These

benefits include less abdominal fat, lower blood pressure, an

improved blood lipid-lipoprotein profile, enhanced insulin

action, and protection from cardiovascular and all-cause

mortality even in the presence of overweight and obesity.

For these reasons, the ADA (4), ACSM (5), IOM (6),

and others (13) recommend habitual physical activity as

primary therapy for those who are overweight because

of its documented long-term success in achieving and

maintaining healthier body weights.

In the few studies that directly compare the effectiveness

of diet versus exercise as weight loss methods, the influence

of exercise alone compared with diet alone is modest,

with an average reduction of approximately 5 kg for

exercise versus 17.5 kg for diet after 3 months to 1 year

of treatment (14). It is important to note that the energy

deficit imposed by diet in these studies was far greater than

that imposed by exercise, explaining the reports of greater

weight loss achieved by diet than exercise. R. Ross, Ph.D.,

and coworkers (14) conducted one of the few controlled

studies wherein the energy deficits induced by diet and

exercise were carefully matched in obese, sedentary,

middle-aged men. The men were randomly assigned to

one of four groups: control, diet-induced weight loss,

exercise-induced weight loss (daily walking for 60 minutes

at 70% of maximal heart rate), and exercise without weight

loss. The negative energy balance induced by diet and/or

exercise was matched in the three experimental groups to be

700 kcal/day for 3 months. The diet- and exercise-induced

weight loss groups lost similar amounts of weight (7.5 kg)

and decreases in abdominal fat. Despite decreases in body

weight, skeletal muscle was preserved in the exercise-induced

weight loss group, whereas it was reduced in the

diet-induced weight loss group. Thus, when the energy

deficits induced by diet and exercise are comparable as

they were in the study by Dr. Ross et al. (14), the two

interventions produce similar weight loss amounts, and

the composition of the weight loss is healthier when

induced by exercise rather than diet.

An important development in the field of exercise

science has been the realization that the quantity of

physical activity needed for health benefit is different

from the amount needed for successful weight loss

maintenance (4, 5, 6, 13). To better clarify the amount

of exercise necessary for long-term weight loss,

Jakicic, Ph.D., FACSM, et al. (15) compared the effects

of varying durations and intensities of exercise on weight

loss after 12 months of treatment in overweight and

obese, sedentary, middle-aged women. Volunteers

were randomized into one of four groups: vigorous

intensity/high duration (200 minutes/week);

moderate intensity/high duration (300 minutes/week);

moderate intensity/moderate duration (200 minutes/week);

and vigorous intensity/moderate duration (150 minutes/

week). The women also were provided with a behavioral

weight loss intervention consisting of a reduction in energy

intake to 1,200 to 1,500 kcal/day and fat intake between

20% to 30% of total energy intake. All groups lost weight

ranging from 6.3 to 8.9 kg with no differences between the

groups. A noteworthy finding was that the women who

reported exercising more than 200 minutes/week or more

than 40 minutes/day lost more weight than the women

who stated that they exercised between 150 and 199

minutes/week or 30 to 39 minutes/day, 11.6 vs 8.5 kg,

respectively. These findings indicated that 30 minutes/day

of moderate intensity physical activity is sufficient for

weight loss and associated health benefits when caloric

intake is restricted; however, greater amounts of exercise

combined with caloric restriction will result in additional

benefit for those willing and able to do so.

The work of Dr. Jakicic et al. (15) and others (5)

indicates that sizeable amounts of daily energy expenditure

are needed to successfully maintain weight loss, defined

at losing 10% of initial body weight and maintaining this

weight loss for a minimum of 1 year. To achieve these

large amounts of daily energy expenditure, individual and

population-based strategies must be instituted to foster an

environment conducive to ample amounts of lifestyle

physical activity. Such strategies recommended by the

Task Force on Community Preventive Services (16)

include the following: 1) community-wide campaigns,

2) point-of-contact strategies such as posting signs

near elevators and escalators encouraging stair use, 3)

comprehensive behavior modification programs, 4) social

support interventions in community settings, and 5) creation

of enhanced access to physical activity sites combined with

informational outreach activities.

In summary:

Physical inactivity has made a significant contribution

to the obesity epidemic.

Physical activity is essential for the long-term

maintenance of a healthy body weight.

Despite this knowledge, the majority of Americans

remain overweight because of their sedentary lifestyles, so

strategies should be instituted to foster an environment

conducive to ample amounts of lifestyle physical activity.

Treatment Recommendations

Individuals will lose weight when they reduce dietary

energy and fat intake and/or engage in greater amounts

of lifestyle physical activity. We acknowledge that to

successfully reverse the obesity epidemic, multimodal

approaches are necessary that combine diet and exercise

alterations based upon sound behavioral science theory.

J.O. Hill, Ph.D., and colleagues (13) recently proposed

that if energy balance was lowered by 100 kcal/day, weight

gain in the general population could be averted. They

suggested that people can simply exercise (e.g., walk)

15 minutes more per day (which is approximately 1 mile of

walking) and/or eat a few less bites at each meal to achieve

this energy deficit. These recommendations imply having

simple behavioral targets for the prevention of weight gain

are key in the treatment of overweight and obesity.

Despite this optimistic public health solution to reversing

the obesity epidemic, evidence indicates that on an

individual basis more intensive, multidimensional

interventions are required. A multidisciplinary approach

for successful weight loss management recommends the

following steps (4, 17):

1. Identify a reasonable weight goal.

2. Prevent additional weight gain.

3. Participate in a program that helps with weight loss

through healthy eating (as opposed to restrictive dieting)

and adequate levels of physical activity.

4. Learn how to prevent relapses.

5. In certain cases, accept an overweight or obese physique

while still encouraging daily exercise and consumption

of a healthy diet.

ACSM (5) also contends that a combination of diet

and exercise is the key to weight loss and the prevention

of weight gain. ACSM's recommendations for overweight

and obese adults are to

Reduce body weight by 5% to 10% of initial body weight

with a sustained weight loss of more than 10% of initial

body weight to maximize long-term health benefits.

Progressively increase physical activity levels to at least

150 minutes (2.5 hours) of moderate intensity physical

activity per week, and when possible progress to 200 to

300 minutes (3.3 to 5 hours) per week or more than

2,000 kcal of energy expenditure.

Reduce current levels of energy intake by 500 to 1,000

kcal/day combined with a decrease in dietary fat of

less than 30% of total energy intake. Thereafter, an

individualized plan of energy intake should be formulated

in combination with a low fat diet (less than 30% of

total energy intake) to prevent weight regain.

Incorporate resistance training into a weight loss program

to improve strength and function; however, it may not

significantly prevent the loss of fat-free mass associated

with a weight loss program.

Consistent with ACSM recommendations are the

recent recommendations of the Institute of Medicine that

advise adults (and children) to engage in 60 minutes of

moderately intense physical activity daily to maintain

normal healthy body weight (BMI 18.5 to 25 kg/m2).

This recommendation includes everything a person does

beyond sleeping and breathing or all activities that contribute

to an active lifestyle such as walking the dog and taking

the stairs versus the elevator or lifestyle physical activity.

Conclusions

In summary, the debate on what approach is most successful

for attainment and maintenance of a healthy body weight

continues because neither diet nor exercise alone appears to

be a clear winner in this regard. Current evidence indicates

that when diet and exercise are used in combination,

30 minutes/day of moderate intensity physical activity

coupled with caloric restriction are sufficient for weight loss.

For successful long-term weight loss maintenance, even

greater amounts of lifestyle physical activity are

recommended that should be supported by multimodal

strategies that include the following: 1) community-wide

campaigns, 2) point-of-contact strategies, 3) comprehensive

lifestyle modification programs, 4) social support

interventions in community settings, and 5) environmental

supports and access combined with informational

outreach activities.

Cheers, Alan Pater