Population Perspectives on Obesity: Etiology and Intervention Robert W. Jeffery, Ph.D. University of Minnesota School of Public Health Division of Epidemiology
Acknowledgement of Mentors and Colleagues! Albert Bandura! Albert Stunkard! John Farquhar! Rena Wing! Jean Forster! Simone French! Henry Blackburn
Purposes Conceptualization of population obesity. Dimensions of the current obesity epidemic and its possible causes. Research on public health approaches to obesity treatment/ prevention.
Conceptualization of Individual vs Population Obesity Individual Definition Health importance Etiology Intervention BMI Individual risk Genetic susceptibility Eating & exercise Decrease susceptibility Pharmacologic/surgical Behavioral/education
Conceptualization of Individual vs Population Obesity: continued Population Definition Prevalence Health importance Population attributable risk Etiology Environmental exposures Eating / exercise opportunity Affluence, Education Intervention Change environmental exposures Education Eating / exercise opportunity / cost
Obesity (BMI 30) prevalence in the US, 1970-94. 25 20 15 10 5 0 1971-74 NHANES-I Flegal et al, 1998 1976-80 NHANES-II 1988-94 NHANES-III
Proximal Causes of Obesity Epidemic! Increased eating! Decreased physical activity
Underlying Causes of Obesity Epidemic!Changes in Environment
Total energy intake per day in the US, 1977 to 1987 2000 1500 1000 500 0 Popkin et al, 2001 1977 1987
Trends in leisure-time physical activity in the Minnesota Heart Survey (min/day), 1980 to 1995. 50 40 30 Men Women 20 1980-82 1990-92 1995-97 Steffen-Batey et al, 2001
Percent change in per capita disappearance of total energy, total fat, and total CHO per day in the US, 1970-94. 30 25 20 15 10 5 0 From USDA, 1995 Total energy Total fat Total CHO 1970 1980 1990 1994
Percent change in per capita disappearance of selected foods per day in the US, 1970-94. 125 100 75 50 25 0-25 Beef Chicken Butter Cheese Fruits/Vegies Soft Drinks 1970 1980 1990 1994 From USDA, 1995
Percent change in food expenditures as a proportion of income in the US, 1970-99. 30 20 10-10 0-20 -30-40 From USDA, 1995 At home Away Total 1970 1980 1990 1994
Fast Food Eating Was Positively Related to BMI in Women BMI Units* Per Fast Food Meal 1.20 1.00.80.60.40.20.00.19 Men **.54 High-income Women **.97 Low-income Women * 1 BMI unit equals approximately 3 kg ** p <.05 Jeffery et al, 1998
Food Advertising Expenditures (millions) Product Amount Year Coca Cola $277 1997 McDonald s $572 1998 Total food industry $11,000 1997 Total USDA expenditures $333 1997 on nutrition education Advertising Age, 1998
Food advertising as a percent of sales averaged across 7 food types,* 1970-90. 5 4 3 2 1 0 1970 1980 1990 * Meat, dairy, canned/frozen fruit, vegetables, grain, bakery, sugar, soft drinks. Almanac of Business & Industrial Financial Ratios, 1995
Total Fat as a Percent of Calories in the US Food Supply 1970 to 1995 44 42 40 38 36 34 From USDA, 1995 Health claim advertising ban lifted 1970 1980 1985 1990 1995
Percent change in means of transportation to work in the US, 1970-90. 20 10-10 0-20 -30-40 -50 US Census, 2001 Car Public Nonmotor 1970 1980 1990
Percent change in hours of TV viewing per week, 1965-99. 300 250 200 150 100 50 0-50 -100 1965 1999 French et al, 2001
TV Viewing Was Positively Related to BMI in Women BMI Units* Per Hour of TV Viewing.80.60.40.20.00.23 Men **.40 High-income Women.70 ** Low-income Women * 1 BMI unit equals approximately 3 kg ** p <.05 Jeffery et al, 1998
Percent change in hours of housework per week in the US, 1965-95. 0-5 -10-15 -20 1965 1975 1985 1995 Bianchi et al, 2000
Percent change in total hours worked for pay per week among married couples the US, 1970-97. 25 20 15 10 5 0 1970 1997 Jacobs & Gerson, 2001
What Can Be Done About the Obesity Epidemic?!Better education about eating and exercise.!reduce environmental exposures that promote overeating and under-exercising.
The Healthy Worker Project (HWP) A randomized trial of worksite interventions for weight loss. Jeffery et al, 1993
HWP Project Overview! Thirty-two (32) worksites employing approximately 20,000 people.! Randomized to treatment or control! Two years of intervention on weight! Evaluation via cohort and crosssectional surveys Jeffery et al, 1993
HWP Intervention! 4 rounds! 6 months duration! No entry restrictions! Self-selected goals! Self-help manual! Biweekly group instruction! Payroll-based incentive system Jeffery et al, 1993
Participation and Short-term Weight Loss Participants 2041 % of all overweight employees 38.3 Mean weight loss (lb) 4.8 Jeffery et al, 1993
HWP: Mean change in BMI over 2 years. 0.10 0.08 0.06 0.04 0.02 0.00-0.02-0.04-0.06-0.08-0.10 Treatment Control Baseline Follow-up * Controlling for age, sex, and education. Jeffery et al, 1993
Minnesota Heart Health Program (MHHP) A 10-year research and demonstration project to evaluate the effectiveness of multicomponent interventions to reduce CVD incidence and mortality Luepker et al, 1994
Description of MHHP! Three matched community pairs! Seven years of intervention including: " risk factor screening " mass media " adult education " worksite intervention " school intervention " restaurant intervention " etc. Luepker et al, 1994
Mean BMI in MHHP Education and Comparison Communities by Year: Cross-sectional Surveys BM I 27.00 26.75 26.50 26.25 26.00 25.75 25.50 25.25 25.00 Jeffery et al, 1995 Comparison Education B (3) B (2) B (1) B 0 E 1 E 2 E 3 E 4 E 5 E 6 E 7-3 -3-2 -2-1 -1 0 1 2 3 4 5 6 7 B and E Years
Pound of Prevention (POP) Randomized trial evaluating the effectiveness of a low cost educational approach in reducing the rate of weight gain with age Jeffery et al, 1999
POP Study Participants! General recruitment through mass media (228 men, 594 women)! Special recruitment of 400 low income women through WIC! Eligibility requirements: " Age 20 to 45 years " Not pregnant in the last year " No serious health conditions Jeffery et al, 1999
Treatments # Control: No contact # Education: Monthly newsletters emphasizing 5 themes: 1. Weigh yourself regularly 2. Eat 2 fruits/day 3. Eat 3 vegetables/day 4. Reduce fat intake 5. Increase exercise/walking Additional education offerings 2 times per year (e.g., classes, contests, correspondence course) # Education + Incentive: Education program (above) + lottery drawing monthly to encourage newsletter reading. Jeffery et al, 1995
Weight change (lb) by treatment group by year. 5 Control 4 Newsletter Newsletter + Incentive 3 2 1 0 Baseline Year 1 Year 2 Year 3 Adjusted means, controlling for age, sex, type, education, and smoking. Jeffery et al, 1999
Cafeteria Study of Price and Availability Influences on Fruit and Salad Consumption! Three (3) weeks baseline observation! Three (3) weeks interventions " 50% price reduction " increased choices! Three (3) weeks return to baseline Jeffery et al, 1994
Number of Fruit Purchases 50 40 30 20 10 0 Baseline Intervention 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 Day Follow-up X = 11 X = 31 X = 14 Jeffery et al, 1994
Pounds of Salad Purchased 50 40 30 20 10 Baseline 0 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 Jeffery et al, 1994 Intervention Day Follow-up X = 8 X = 24 X = 12
Fruit Sales as a Function of Price Fruit Sales as a Function of Price Mean weekly fruit sales 100 80 60 40 20 0 French et al, 1997 Baseline 1 Low price Baseline 2 Average School 1 urban School 2 Suburban Average vs each school
Carrot Sales as a Function of Price Carrot Sales as a Function of Price Mean weekly carrot sales 160 140 120 100 80 60 40 20 0 Baseline 1 Low price Baseline 2 Average School 1 urban School 2 suburgan Average vs each school French et al, 1997
Low-Fat Snack Sales in Vending Machines (%) as a Function of Price % 50 40 30 20 10 0 French et al, 1997 French et al, 1997 Same price 50% low-fat discount Same price
CHIPS! Randomized trial with Latin Squares design studying effects of price and health education on vending machine snack choices.! 12 worksites and 12 high schools! Health education: " None " Fat color codes " Fat color codes + promotional ads! Pricing: " Equal " Low-fat discount of 10%, 25%, 50% French et al, 2001 French et al, 2001
Effect of Price on Low-Fat Snack Sales % Sales LF Snacks 25 20 15 10 5 0 Equal -Ź10% -Ź25% -Ź50% Price % Increase in sales: 9% 39% 93% French et al, 2001 French et al, 2001
% Sales LF Snacks Effect of Health Promotion on Low-Fat Snack Sales 25 20 15 10 5 0 No Label Label Label & Sign Promotion % Increase in sales: 1% 8% French et al, 2001 French et al, 2001
Results of Two Studies on the Effects of Price on the Use of Exercise Facilities 1. University employees given membership to a campus recreation facility did not use it more than employees not given memberships. French, et al French, et al 2. Only 2 of 616 participants in a weight gain prevention study used free access to a community YWCA that included exercise facilities and free child care. Sherwood, et al
Percentage of People Using the Stairs During Each Phase of the Study % People Using the Stairs 20 15 10 5 0 11.1 a No Intervention 12.7 a 15.5 b Signs Signs + Music + Artwork 13.8 c No Intervention NOTE: Percentages with unshared superscripts differ significantly, p <.05. Boutelle et al, 2002
Policy Implications of an Environmental Perspective on Obesity 1. Reduce food availability Number of outlets Hours of operation Portion sizes 2. Increase food price All food Energy-dense food 3. Limit food promotion
Public Opinion on Who Is Responsible for Today s Diet-Related Problems (n = 821)! Individuals 80%! Stores 2%! Manufacturers 14% Jeffery et al, 1990
Public Opinion of 8 Specific Public Policy Measures Related to Food Positive 1. Limit food advertising on children s TV X 2. Require schools to serve low-fat food X 3. Ban high-fat food from school vending machines X 4. Warning labels on high-fat food X Neutral Negative Jeffery et al, 1990
Public Opinion of 8 Specific Public Policy Measures Related to Food: continued Positive Neutral Negative 5. Tax incentives for restaurants to serve low-fat food. X 6. Tax incentives for farmers to produce lower fat meat and dairy products. X 7. Tax high-fat food. X 8. Restrict high-fat food sales to minors. X Jeffery et al, 1990
Current Research Directions Current Research Directions Further examine environmental correlates of obesity Expand environmental change research to include new exposures and body weight outcomes