Impact of Exercise on Obesity Management

Topic Outline

• The Role of Physical Activity in Obesity Management for:– Weight loss

– Weight loss maintenance

– Prevention of obesity

– Reducing general health risks

• Mechanisms of Action

• Current Recommendations for Physical Activity in Obesity Therapy

• Translating Physical Activity Recommendations into Increased Physical Activity in Patients

Weight Loss: What Works?

1Zachwieja JJ. Endocrinol Metab Clin North Am 1995;25:965-988.

Effect of Physical Activity Without Diet on Body Weight Loss1

Mode Frequency Weight Loss

Epstein and Wing Walk/run 2 - 5x/wk 0.09 kg/wk

Ballor and Kessey Walk/run/cycle 3 - 4x/wk 0.1 kg/wk

Garrow and Summerbell Walk/run/cycle 3 - 4x/wk 0.1 kg/wk

Hadjiolva, et al Various Daily(10 hrs/day) 1.8 kg/wk

Lee, et al Military Training 5x/wk 0.6 kg/wk

Physical Activity Usually Does Not Increase Short-Term

Diet-Induced Weight Loss

Wing. Med Sci Sports Exerc. 1999;31(suppl):S547.Each study ranged from 4 to 6 months*P < 0.05 vs diet-only group

Blonk 1994

Sweeney 1993

-15 -10 -5 0

Weight Loss (kg)

*

Diet only Diet + exercise

Wadden 1997

Ross 1996

Marks 1995

Ross 1995

Bertram 1990

Physical Activity and Weight Loss

• Most studies suggest a reasonable amount of physical activity

– does not produce weight loss− Exercise alone - 0.06 to 0.1 kg/week− Dose response relationship

– does not significantly increase initial weight loss over what is obtained by caloric restriction alone

“Do not judge the impact of physical activity by weight loss”

Dr. Steve Blair - Cooper Institute

September 20, 2004

Weight Loss Maintenance: What Works?

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BCDD BCDD &Exercise

VLCD VLCD &Exercise

8 weeks 18 months

Adapted from Pavlou KN, et al. Am J Clin Nutr. 1989;49:1115-1123.

Weight Loss Maintenance: What Works?

Jeffery RW et al AJCN 2003;78:684-9.

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n = 84

n = 102n = 87

n = 76

n = 80

n = 87

Physical Activity and Weight Loss Maintenance

• Data from case studies, correlation studies and randomized control trails have all concluded that high levels of physical activity facilitate maintenance of weight loss long-term

Prevention: What Works?

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Control Exercise

Donnelly J, Jacobsen D, Hill JO. Archives of Internal Medicine 163:1343-1350, 2003.

Freshman and Sophomore Women at the University of Kansas

Freshman and Sophomore Women at the University of Kansas

• 225 minutes/week prevented weight gain in women at risk (2.3 kg/16 months)

• 225 minutes produced a weight loss in men at risk (5.2 kg/16 months)

• Women 439 kcal/session (5.4 kcal/kg)

• Men 667 kcal/session (6.7 kcal/kg)

Donnelly J, Jacobsen D, Hill JO. Archives of Internal Medicine 163:1343-1350, 2003.

Physical Activity and General Health

• Moderate levels of cardiorespiratory fitness substantially reduce mortality risks associated with overweight and obesity

• Moderate levels of cardiorespiratory fitness can be developed in 30 minutes of activity at least 5 days per week

HERITAGE Family Study

Katzmaryck PT, Leon AS, Wilmore JH, et al. Med Sci Sports Exerc, 2003; Vol. 35, No. 10, 1703–1709.

Prevalence of individual risk factors before and after 20 wk of aerobic exercise training in the HERITAGE Family Study among 105 participants with the metabolic syndrome at baseline. *P < 0.05 pre- versus post-training.

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0High TG Low HDL-C High BP High Glucose High WC Metabolic Syndrome

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Why the difference in impact for physical activity between weight loss and weight loss maintenance?

Differences Between Weight Loss and Weight Loss Maintenance

Weight Loss Maintenance of Weight Loss

• Time limited

• Requires a negative energy balance

• Reduced caloric intake is critical

• Physical activity not required for success

• Common

• Life-long

• Requires energy balance at a reduced body weight

• Physical activity is critical for success

• Rare

Mechanism of Action

• Makes it more likely for patients to remain in Energy Balance at a reduced body weight

• Why? Possibilities include:– Direct compensation for diet indiscretions

– Prevent or attenuate metabolic efficiency associated with weight loss

– Improved self-efficacy or mood

– Improved satiety/hunger

– Allows better “physiological” matching of intake and expenditure to occur

Why Is Physical Activity Critical for Long-Term Success?

Physiological Control Maximized

Energy Intake

Energy Expenditure

Obesity Conducive Environment

CognitiveControl Required

Activity

Intake

A B

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Ener

gy Bal

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Potential Effects of Increasing Physical Activity vs. Decreasing Intake on

Encouraging Physiological Energy Balance

Physical Activity Recommendations:How Much is Enough?

“30 minutes of physical activity every day is all I need to do to manage my weight”

A Common Patient Misconception

How Much is Enough?Current PA Recommendations

• Minimal public health recommendations to improve health related outcomes– 30 min moderate activity most days of the week (150

minutes/week)– CDC - Centers for Disease Control – ACSM - American College of Sports Medicine – SG - Surgeon General

• Maximize weight loss and prevent weight regain– 45-60 minutes/day

– IOM - Institutes of Medicine– 60-90 minutes/day

– IASO - International Assoc for Study of Obesity– 60 minutes/day (300 minutes/week)

– ACSM - American College Sports Medicine

• Preventing general weight gain– Unclear

Weight Loss Maintenance: How Much is Enough?

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0 3 6 9 12Time (months)

We

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t (k

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Sedentary Moderately active Active

Schoeller et al, AJCN 1997;66:551-6.

• Women in the physically active group gained the least weight after reaching their target for weight loss

• Retrospective analysis: Threshold of 11 kcal/kg of body wt/day

• 80 minutes of moderate intensity activity or 35 minutes of vigorous activity

• Supports that body weight is better regulated at a higher energy flux

Schoeller et al, AJCN 1997;66:551-6.

Weight Loss Maintenance: How Much is Enough?

Average Energy Expended in Physical Activity in the NWCR

3293

26822545

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Klem et al, AJCN 1997;66:239-46.

What About Intensity?

• Studies suggest the intensity of physical activity may have limited impact on weight control when total energy expenditure (TEE) is fixed

• High levels of energy expenditure (EE) improve weight management – So if vigorous intensity results in greater EE weight

loss outcomes will improve

– So if moderate intensity results in greater EE weight outcomes will improve

• Moderate intensity provides health benefits while presenting low to moderate health risks

Planned vs Lifestyle Activity

• Planned Activity- completed in a discrete period of time, moderate to high intensity– 30 to 60 minutes

– Walking, swimming, biking

• Lifestyle Activity- completed during everyday tasks– Parking further away, taking stairs, walk to meetings

Mean Changes in Body Weight for Lifestyle Activity vs Aerobic Exercise

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Diet +Lifestyle

Anderson et al. JAMA 1999; 281: 337.

Long vs Short Bouts• Multiple short bouts are as effective as one long

bout and perhaps may facilitate efforts to increase activity

• Helps address the barrier of perceived lack of time

• Multiple short bouts increase adoption of physical activity during first 6 months

• Long-term impact is less clear

Jakicic JM et al. JAMA 1999;282(16):1554-60.Jacobsen DJ et al. Int J Sports Med 2003;24:459-64.

Physical Activity - The “Magic Pill”What Patients Want…

• Currently available• Safe, cheap and effective• Increase my “metabolism” • Burn fat as fuel• Allow me to eat more food without

gaining weight• Make me “healthier”

How to Get Your Overweight Patients to Be More Active

• For many individuals, starting a structured exercise program is not possible

• Therefore: Implement small lifestyle changes to increase daily physical activity– Park at end of lot when driving to store

– Only have one phone in house so patient has to walk to use it

– Find the stairs!

– Walk to a co-worker’s office at work instead of calling on the phone

– Use elevators only if going up more than 2 floors

• Decrease sedentary activity

How to Get Your Overweight Patients to Be More Active

Lifestyle Activity Program

• Wear a pedometer every day for a week to determine baseline

• Increase steps by 500 steps/day /week

• Ultimate goal 10,000 - 15,000 steps/day

• 500 steps = 5 minutes walking moderate

• Helps set goals and gives instantaneous feedback

• Do all those little changes add up?

www: Americaonthemove.org

Then What?

• After these lifestyle alterations are in place, start on a structured exercise plan

– Start slow - perhaps as little as 5 - 10 min of activity per day (whatever they enjoy and will continue to do)

– Total amount of activity is what counts

Conclusions

• Physical activity recommendations of 30 minutes most days of the week are based on improving cardiovascular health - a good initial or minimal goal

• 60 - 80 minutes of physical activity may be what is necessary to prevent regain following a weight loss (long-term goal)

• Risk factors associated with Metabolic Syndrome improve with physical activity

• How to get patients to do what we know it takes is the real problem

• Lifestyle changes and short bouts of activity in sedentary individuals may be the place to start

• Gradual increase over 1 - 2 years may be necessary

• Long-term adherence is the most important goal