Impact of Exercise on Obesity Management
Mar 26, 2015
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?
0
2
4
6
8
10
12
14
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.
-10
-9
-8-7
-6
-5
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-3-2
-1
0
0 6 12 18Time (mo)
We
igh
t C
ha
ng
e (
kg
) 1000 kcal/wk
2500 kcal/wk
*
**
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?
73
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83
Wei
gh
t (k
g)
Base 4 Months 9 Months 12 Months 16 Months
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.
100
90
80
70
60
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10
0High TG Low HDL-C High BP High Glucose High WC Metabolic Syndrome
Pre-Training Post-Training
*
*
*
*
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
C
Ener
gy Bal
ance
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?
5860626466687072747678
0 3 6 9 12Time (months)
We
igh
t (k
g)
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
0
500
1000
1500
2000
2500
3000
3500
4000
KC
al
Women Men All Subjects
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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-8
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0
0 8 16 24 32 40 48 56 64
Week
Ch
ang
e in
Wei
gh
t (k
g)
Diet + Aerobic
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