the role of physical activity in the prevention and treatment of obesity origins of obesity—2011...
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The Role of Physical Activity in the Prevention and Treatment of Obesity
Origins of Obesity—2011 SymposiumIowa State University
May 9, 2011
Steven N. BlairDepartments of Exercise Science &
Epidemiology/BiostatisticsUniversity of South Carolina
Disclosures• Medical/Scientific Advisory Boards
– Jenny Craig, Inc– Alere– Technogym– Cancer Foundation for Life– Santech– Clarity Project
• Research Funding– NIH– Body Media– Coca Cola– Department of Defense
Acknowledgements • Co-investigators
– Xuemei Sui
– Tim Church
– James Hebert
– Greg Hand
– Ian Janssen
– Francisco Ortega
– Jonatan Ruiz
– Steve Hooker
– Michael Beets
– Sara Wilcox
– Chris Riddoch
– Andrew Jackson
– Paul McAuley
– Susumu Sawada
– Andy Ness
• Post-doctoral scholars– D.C. Lee
– Meghan Baruth
– Jongkyu Kim
– Enrique Artero
• PhD students– Amanda Paluch
– John Sieverdes
– Vaughn Barry
– Jonathan Mitchell
– Won Byun
– Tatiana Warren
– Andrea Maslow
– Will Lyerly
– Ed Archer
Do We Have an Epidemic of Obesity?
Global Trends in
Adult Obesity
International Obesity Taskforce. http://www.iotf.org/database/index.asp.
Do we know how to prevent obesity?
Yes!!!!!
Sit less and stand more
How to StandDetailed instructions from the Department of Health and Human Services
Introducing “Exertol”Your Physical Activity Prescription
Which causes more deaths in the U.S.—smoking or obesity?
• ~40% of U.S. adults think obesity causes at least as many deaths as does smoking
• ~20% of U.S. adults think obesity causes more deaths than smoking
• The truth– Smoking causes ~440,000 deaths/year– Obesity causes ~110,000 deaths/year
Definitions for adultsBody mass index (BMI) – weight/height 2
• Underweight: BMI < 18.5• Normal weight: BMI 18.5-<25• Overweight*: BMI 25-<30• Obesity: BMI 30 +
BMI 18.5 BMI 25 BMI 30
162 cm (64 in)
49 kg (107 lbs)
66 kg (145 lbs)
79 kg (174 lbs)
178 cm (70 in)
59 kg (129 lbs)
79 kg (174 lbs)
95 kg (209 lbs)
* WHO defines overweight as BMI 25+
Courtesy of Katherine Flegal
SOURCE: Harris 2008 Int J Obesity
Courtesy of Katherine Flegal
SOURCE: Harris 2008 Int J ObesityCourtesy of Katherine Flegal
SOURCE: Harris 2008 Int J Obesity
Courtesy of Katherine Flegal
SOURCE: Harris 2008 Int J ObesityCourtesy of Katherine Flegal
Courtesy of Katherine Flegal
Obesity and Diabetes• We hear a great deal, in both the
scientific literature and popular press, about the epidemics of obesity and diabetes– In fact, some dummies even use the term
“diabesity”
• What is the rate of type 2 diabetes in U.S. individuals under 45 years of age?
U.S. Rates of Diagnosed Type 2 Diabetes in Persons under 45
Years of Age in 2010• 1.4%
• Of course this is higher than it was in 1980– 0.6%
• Diagnosed diabetes in those under 20 years of age in the U.S.– 0.26%
Source: CDC website--
Body Mass Index and Mortality
Relation between mortality and BMI
Data from Lew EA: Mortality and weight: insured lives and the American Cancer Society studies. Ann Intern Med 103:1024-1029, 1985.
Excess deaths associated with underweight, overweight and obesity
[Reference Range 18.5 – 24.9]
-200,000
-150,000
-100,000
-50,000
0
50,000
100,000
150,000
BMI <18.5 BMI 25-<30 BMI 30-<35 BMI 35+
33,746
-86,094
29,843
82,066
Flegal et al JAMA 293:1861, 2005
BMI 30+: 111,909 deaths
It’s calories that count
Energy InEnergy In Energy OutEnergy Out
BMRBMRThermic effect of foodThermic effect of foodMedia (TV,PC)Media (TV,PC)CarsCarsNo heavy labourNo heavy labourExerciseExercise
Portion sizePortion sizeHigh-fat foodsHigh-fat foodsEnergy denseEnergy denseLow-fiberLow-fiberSoft drinksSoft drinksSnack foodsSnack foods
Cause(s) of the Obesity Epidemic• Increases in energy intake
• Decreases in energy expenditure
• Changes in specific micro or macronutrients
• Combination of increases in intake and decreases in expenditure
– 50/50?
– 30/70?
– 70/30?
Trends in Energy IntakeNHANES 1971-2000
• Data sources– NHANES I—1971-1974– NHANES II—1976-1980– NHANES III—1988-1994– NHANES—1999-2000
• Surveys were representative samples of noninstitutionalized U.S. women and men aged 20 to 74 years
Source: MMWR Feb 6, 2004
Trends in Energy Intake1971 to 2000, Men, NHANES
0
500
1000
1500
2000
2500
3000
All Ages 20-39 y 40-59 y 60-74 y
1971-741976-801988-941999-00
Kcal/day
Source: MMWR Feb 6, 2004
Trends in Energy Intake1971 to 2000, Women, NHANES
0
500
1000
1500
2000
2500
All Ages 20-39 y 40-59 y 60-74 y
1971-741976-801988-941999-00
Kcal/day
Source: MMWR Feb 6, 2004
NHANES Survey Methods 1971-2000
• NHANES I and NHANES II– 24-hour dietary recall, Monday-Friday
• NHANES III and NHANES– 24-hour dietary recall, Monday-Sunday
• Other changes in methodology included better probing techniques and better training of interviewers
• Other changes in dietary behavior included more meals eaten away from home and increasing portion sizes
Jobs in U.S. Over Last 50 Years
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
1960 1970 1980 1990 2000 2010
Year
%
Service Jobs
Goods ProducingJobs
Agricultural Jobs
Church TS et al. PLoS One 2011
Physical Activity Intensity
0
10
20
30
40
50
60
1960 1970 1980 1990 2000 2010
Year
% T
otal
Priv
ate
US
Job
s
Sedentary (<2 METS)
Light (2.0 to 2.9 METS)
Moderate(≥3.0 METS)
Church TS et al. PLoS One 2011
Daily Occupational Caloric Expenditure
1,150
1,250
1,350
1,450
1,550
1960 1970 1980 1990 2000 2010
Year
Occ
up
atio
n R
ela
ted
Da
ily E
ne
rgy
Exp
en
ditu
re (
calo
rie
s) Men
Women
-140 daily kcals
-120 daily kcals
Church TS et al. PLoS One 2011
Men: Predicted vs. NHANES
70
75
80
85
90
95
1960-62 1971-74 1976-80 1988-94 1999-02 2003-06
Wei
ght
(kg)
NHANES
Predicted Based on Change in OccupationRelated Energy Expenditure
Men
Bas
elin
e
Church TS et al. PLoS One 2011
60
65
70
75
80
1960-62 1971-74 1976-80 1988-94 1999-02 2003-06
Wei
ght
(kg)
Women
Bas
elin
e
Women: Predicted vs. NHANES
Church TS et al. PLoS One 2011
The Energy Balance Study
TimelineYour participation in the study will
last approximately 13 months.
All enrolled participants will be asked to complete all scheduled measures.
6 Follow-up Visits
-12 months-
3 Baseline Visits
-2-3 weeks--2 weeks-
Activity assessmentToday Baseline Visits 1-3 Day 7 Day 14Month 9Month 6Month 3 Month 12
Food Portion-size TrainingPurpose: to help estimate food
portion sizesHelpful for dietary recalls.Time: 10 minutes.
Dietary Recalls
Dietician will call and ask what you ate the previous day.Time: 15-20 minutes
Three random recalls will occur after your Baseline Visit 3.
Physical Activity Monitors You will be wearing 2 monitors Armband
Lightweight monitor worn on the upper left arm
Estimates energy expenditure and physical activity
ActivPAL Small device worn on your thigh (under
clothing) Measures sitting and lying down time.
Both monitors should be worn at all times except in water Wear for 10 days 38
Body Composition Scan
~20-25 minutesIt measures:
Fat mass Lean mass
Requires small radiation exposure.Less than 1 day's exposure to the sun.
(~ 3 hours of lawn mowing)
Resting Metabolic RateMeasures the number of
calories you burn at rest.
Participant rests:45-60 minutes Quiet room
Cardiorespiratory Fitness, BMI, and Mortality, ACLS Men• 25,389 men followed 8.5 years
• 673 deaths in 212,364 MY
• Cardiorespiratory fitness assessed by a maximal exercise test
• Calculated age-adjusted death rates for BMI and fitness categories
Barlow et al. Int J Obes 1995; 19:Suppl 4, S41-4
Assessment of Body Weight• I do not like to subject study participants to
the embarrassment of actually measuring their weight, since so many are overweight/obese
• We have an undergraduate student estimate height and weight of the participants
• We did a validation study by actually measuring height and weight of 100 consecutive participants
• The student’s estimate was valid, r=0.4
Age-Adjusted Death Rates by Fitness and BMI Categories
0
10
20
30
40
50
60
70
<27 27-30 >30
Low fit
Mod fit
High fit
# deaths 133 189 119 63 67 17 75 19Man-Yrs 25,537 64,103 57,004 15,000 20,749 7,341 14,301 8,240
Deaths/10,000 MY
Barlow et al. Int J Obes 1995; 19:Suppl 4, S41-4
Results held after adjustment for health status, smoking, glucose,
cholesterol, & BP
Assessment of Body Weight• I do not like to subject study participants to
the embarrassment of actually measuring their weight, since so many are overweight/obese
• We have an undergraduate student estimate height and weight of the participants
• We did a validation study by actually measuring height and weight of 100 consecutive participants
• The student’s estimate was valid, r=0.4
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Adj RR*
<17 17-25 >25 <17 17-25 >25
Fit
Unfit
All-cause Mortality CVD Mortality
*adjusted for age, exam year, smoking, alcohol, & parental historyLee CD, Blair SN, & Jackson AS. Am J Clin Nurt 1999; 69:373-80
RR for All-cause and CVD Mortality in Fit and Unfit
ACLS Men by Body Fat Categories
Body Fat%
Body Fat%
Adjusted RR for All-Cause Mortality by Fitness and Waist Circumference
• Waist circumference measurements in a subgroup 14,043 men
• 162 deaths in 78,008 man-years
• RR adjusted for age, examination year, smoking habit, alcohol intake, and parental history of CHD
00.5
11.5
22.5
33.5
44.5
5
Adj RR
Low Moderate High
Waist Circumference (cm)
Fit
Unfit
<87 87-<99 99
Lee CD, Blair SN, & Jackson AS. Am J Clin Nurt 1999; 69:373-80
Adjusted RR for All-Cause Mortality by Fitness and BMI, ACLS Women
0
0.5
1
1.5
2
2.5
3
3.5
4
Adj RR*
NormalWeight
Overweight Obese
Fit
Unfit
Farrell et al. Obes Res. 2002; 10:417-423
*adj for age, exam year,smoking, & healthstatus
Joint Associations of CRF and % Body Fat with All-cause Mortality, ACLS Adults 60+
0
10
20
30
40
Fit Unfit
Normal
Obese
Death rate/1,000 person-years
Rates adjusted for age, sex and exam year
Deaths 151 190 29 72
Sui M et al. JAMA 2007; 298:2507-16
CVD Mortality Risk* by Fitness and BMI Categories, 2316 Men with Diabetes,
179 CVD Deaths
0
1
2
3
4
5
6
7
8
9
10
Ris
k o
f C
VD
Mo
rta
lity
18.5 < BMI <25.0 25.0 ≤ BMI <30.0 30.0 ≤ BMI < 35.0
Re
fere
nc
e
Church TS et al. Arch Int Med 2005; 165:2114*Adj for age and examination year
p for trend <0.0001p for trend <0.0001 p for trend <0.002
Attributable Fractions of Health Outcomes For Low Cardiorespiratory Fitness and
Other Predictors, ACLS
•Attributable fraction (%) is the estimated number of deaths due to a specific characteristic
•Based on strength of association•Prevalence of the condition
Relative Risks and Attributable Fractions of All-Cause and CVD Mortality by BMI
Categories in Men
• 25,714 (1,025 all-cause and 439 CVD deaths) men aged ≥20 years in the ACLS.
• 10 years of follow-up.• Attributable fractions are adjusted for
age, examination year, BMI, parental history of CVD, and each other item in the table.
Wei M. et al., JAMA, 1999
Relative Risks (RR) and Attributable Fractions (AF) of All-Cause Mortality by
BMI Categories in MenNormal Overweight Obese
RR (95% CI) AF, % RR (95% CI) AF, % RR (95% CI) AF, %
Baseline CVD 2.3 (1.8-2.9) 19 2.0 (1.6-2.4) 19 2.4 (1.7-3.5) 27
Diabetes 1.3 (0.9-1.8) 2 1.6 (1.3-2.0) 6 1.5 (1.1-2.2) 9
High cholesterol
1.0 (0.8-1.3) 0 1.3 (1.1-1.6) 8 1.7 (1.2-2.3) 18
Hypertension 1.5 (1.2-1.9) 12 1.4 (1.2-1.7) 13 1.1 (0.8-1.4) 4
Current smoker
1.4 (1.1-1.8) 7 1.5 (1.2-1.9) 9 1.5 (1.0-2.1) 9
Low fitness 1.6 (1.3-2.1) 10 1.7 (1.4-2.0) 18 2.3 (1.5-3.4) 44
Wei M. et al., JAMA, 1999
Summary• Indicators of obesity and physical
inactivity are predictors of morbidity and mortality
• Cardiorespiratory fitness is an objective marker of habitual physical activity
• Adjustment for cardiorespiratory fitness dramatically attenuates or eliminates associations of obesity markers and most health outcomes
2008 Physical Activity Guidelines for Americans
At-A-Glance
U.S. Department of Health and Human Services
www.health.gov/PAGuidelines/
55
Physical Activity Guidelines
• For all individuals, some activity is better than none. More is better.
• For fitness benefits, aerobic activity should be episodes of at least 10 minutes.
• Physical activity is safe for almost everyone. The health benefits of physical activity far outweigh the risks.
56
Key Guidelines – Adults (ages 18–64)
• Minimum levels a week– 2 hours and 30 minutes (150 minutes)
moderate-intensity aerobic activity; or– 1 hour and 15 minutes (75 minutes)
vigorous-intensity aerobic activity; or– An equal combination
• Muscle-strengthening activities that involve all major muscle groups should be performed on 2 or more days of the week.
57
Key Guidelines – Adults (ages 18–64) (cont.)
• For additional health benefits– 5 hours (300 minutes) moderate-
intensity aerobic activity a week; or– 2 hours and 30 minutes (150 minutes)
vigorous-intensity aerobic activity a week; or
– An equivalent combination
Overview• Medical care costs in the U.S are ~17%
of GNP, by far the highest in the world• By traditional public health markers
such as longevity, chronic disease rates, infant mortality, etc; the U.S. ranks far behind many other countries
• Most health problems are the result of unhealthy lifestyles
• We must be more aggressive in integrating lifestyle interventions into medical practice and public health programs
How to Promote Healthful Lifestyles
• Relatively new area of research
• Application of theories, models, & methods from behavioral science
• Social Cognitive Theory, Transtheoretical Model (Motivational Readiness), etc– Helping individuals use cognitive and
behavioral strategies to implement behavioral change
Lessons Learned from Physical Activity Intervention Studies
• Individuals who use cognitive and behavioral strategies are more likely to be active at 24 months than individuals who do not use these strategies
• Approximately 25-30% of initially sedentary persons who participate in Active Living will be meeting consensus public health guidelines for physical activity at 24 months
Behavioral Approaches to Physical Activity Interventions
• Theoretical foundations– Social Learning Theory– Stages of Change Model– Environmental/Ecological Model
• Methods– Problem solving– Self-monitoring– Goal setting– Social support– Cognitive restructuring– Incremental changes– Manipulating the environment
Active Living Every Day
S Blair takes no personal royalties from the ALED book
How to Achieve Lifestyle Change
• Counseling by a PhD level behavioral psychologist
• Counseling by B.A. level health educators
• Counseling by mail and telephone
• Counseling by electronic communications
• RCT with 4 arms:
1.) Standard Care group included self-help with a diet and PA manual
2.) GWL health counselor and 14 sessions
3.) GWL + SenseWear™ Armband group
4.) SWA alone
• Follow-up data collection visits occur at month 4 and month 9
LEAN Study Design
Effects across time for weight. Estimates adjust for age, gender, race, education, and wave.
92
94
96
98
100
102
104
Baseline Month 4 Month 9
We
igh
t (K
g)
GWL
GWL+SWA
SWA alone
Standard care
How Should We Deal with the Obesity Epidemic?
• Understand energy balance
• Design interventions to address the problem– Public policy– Educational programs– Clinical medicine– Technological lifestyle interventions
• Conduct research to test interventions
• Implement successful interventions