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