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OBESITY AND THE REGULATION OF BODY WEIGHT. OBESITY: A Huge Public Health Problem. Definition of obesity: BMI > 30 Definition of overweight : BMI > 25. BMI = weight (kg)/ height 2 (m). Obesity Trends* Among U.S. Adults BRFSS, 1985.
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OBESITY: A Huge Public Health Problem Definition of obesity: BMI>30 Definition of overweight: BMI >25 BMI = weight (kg)/ height2 (m)
Obesity Trends* Among U.S. AdultsBRFSS, 1985 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% www.cdc.gov
Obesity Trends* Among U.S. AdultsBRFSS, 1986 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14%
Obesity Trends* Among U.S. AdultsBRFSS, 1987 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14%
Obesity Trends* Among U.S. AdultsBRFSS, 1988 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14%
Obesity Trends* Among U.S. AdultsBRFSS, 1989 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14%
Obesity Trends* Among U.S. AdultsBRFSS, 1990 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14%
Obesity Trends* Among U.S. AdultsBRFSS, 1991 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19%
Obesity Trends* Among U.S. AdultsBRFSS, 1992 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19%
Obesity Trends* Among U.S. AdultsBRFSS, 1993 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19%
Obesity Trends* Among U.S. AdultsBRFSS, 1994 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19%
Obesity Trends* Among U.S. AdultsBRFSS, 1995 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19%
Obesity Trends* Among U.S. AdultsBRFSS, 1996 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19%
Obesity Trends* Among U.S. AdultsBRFSS, 1997 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% ≥20%
Obesity Trends* Among U.S. AdultsBRFSS, 1998 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% ≥20%
Obesity Trends* Among U.S. AdultsBRFSS, 1999 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% ≥20%
Obesity Trends* Among U.S. AdultsBRFSS, 2000 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% ≥20%
Obesity Trends* Among U.S. AdultsBRFSS, 2001 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% 20%–24% ≥25%
Obesity Trends* Among U.S. AdultsBRFSS, 2002 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% 20%–24% ≥25%
Obesity Trends* Among U.S. AdultsBRFSS, 2003 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% 20%–24% ≥25%
Obesity Trends* Among U.S. AdultsBRFSS, 2004 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% 20%–24% ≥25%
Obesity Trends* Among U.S. AdultsBRFSS, 2005 (*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% 20%–24% 25%–29% ≥30%
Obesity Trends* Among U.S. AdultsBRFSS, 2006 (*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% 20%–24% 25%–29% ≥30%
Obesity Trends* Among U.S. AdultsBRFSS, 2007 (*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% 20%–24% 25%–29% ≥30%
Obesity Trends* Among U.S. AdultsBRFSS, 2008 (*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person) No Data <10% 10%–14% 15%–19% 20%–24% 25%–29% ≥30%
% From: Handbook of Obesity: Etiology and Pathophysiology, 2nd edition, G.A. Bray and C. Bouchard, editors, Marcel Dekker, NY,2004
Obesity is a risk factor for: • Type 2 diabetes • Hypertension • Atherosclerosis • Some types of cancer • Asthma • Gall bladder problems • Fertility problems • Osteoarthritis • Sleep disordered breathing • Gastroesophageal reflux
Prevalence of type 2 diabetes by BMI From: Handbook of obesity, Marcel Dekker Inc, 2004
1990 1995 2001 Diabetes Trends* Among Adults in the U.S.,(Includes Gestational Diabetes)BRFSS, 1990,1995 and 2001 Source: Mokdad et al., Diabetes Care 2000;23:1278-83; J Am Med Assoc 2001;286:10.
What’s my BMI? About 30.5 (based on height of 1.87 m and weight of 107 kg)
Normal BMI doesn’t necessarily mean normal body fat A. Romero-Corral et al, Eur. Heart J. 31:737-746, 2010
Body fat increases disease risk in normal weight subjects A. Romero-Corral et al, Eur. Heart J. 31:737-746, 2010
Risk of premature death 15 20 25 30 35 BMI
Risk factors for the development of obesity • Genetics • animals can be bred for fatness • there are inbred strains of mice and rats that are spontaneously obese • whole genome wide genetic studies have identified several genes associated with obesity • Environment • Animals on a high fat diet gain weight • Human who live in other cultures gain weight when they move to the US or other places with a Western diet • Animals born to obese mothers tend to also become obese • Amount of sleep affects weight gain
Wildtype (C57BL/6J) Ob/Ob
Risk factors for the development of obesity • Genetics • animals can be bred for fatness • there are inbred strains of mice and rats that are spontaneously obese • whole genome wide genetic studies have identified several genes associated with obesity • Environment • Animals on a high fat diet gain weight • Human who live in other cultures gain weight when they move to the US or other places with a Western diet • Animals born to obese mothers tend to also become obese • Amount of sleep affects weight gain
Risk factors for the development of obesity • Genetics • animals can be bred for fatness • there are inbred strains of mice and rats that are spontaneously obese • whole genome wide genetic studies have identified several genes associated with obesity • Environment • Animals on a high fat diet gain weight • Human who live in other cultures gain weight when they move to the US or other places with a Western diet • Animals born to obese mothers tend to also become obese • Amount of sleep affects weight gain
Short sleep duration increases BMI From: Taheri et al, PLoS Med 3:e62, 2004
Sleep and Obesity • Elevations of BMI are observed in subjects who sleep fewer than • 6 h per night • Childhood sleeping problems predict adult BMI • Experimental acute sleep curtailment increases hunger and appetite • especially for energy rich foods • -Mice in which circadian rhythms are disrupted become obese • More than 33% of adolescents get less sleep than recommended
WHY IS OBESITY INCREASING? • 1) Genetics? Unlikely. It takes thousands of years to • change the gene pool that drastically (but could be • epigenetic effects). • 2) Changes in environment? • Diet: more carbohydrates and less fat, also • different types of fat • Exercise: more sedentary lifestyles • 3) Gene environment interactions? Susceptibility genes • that are only expressed in conjunction with certain diets
Koh-Banerjee et al, Am J Clin Nutr, 2003 Not all fats are created equal: • Amount of transfat in diet is significantly related • to waist circumference gain • Total amount of fat in diet is not
Also called “partially hydrogenated” oil • Performed to increase shelf life and increase flavor stability • Present in most processed foods • Makes fat solid at room temperature
Consumption of trans fats increases the risk of heart disease Mozaffarian et al NEJM 354:1601-1613, 2007
HOW IS BODY WEIGHT REGULATED? Body weight represents a balance between calorie input and calorie expenditure. InputsExpenditures -food eaten - basal metabolic rate - cost of food digestion (liver) - exercise