Simon Thornley Public Health Physician/ PTF/ PhD student University of Auckland Sugar, addiction and obesity
Summary • What is science? • Is there an obesity epidemic? • A brief history of nutrition • I get involved… • Food addiction • What next?
What is science? • “In God we trust, all others must bring data” • William Edwards Deming • “First establish the facts, then seek to explain them” Aristotle • Anarchistic • Consensus not useful • Hypothesis and argument • Disproving useful, not proof. • Probabilities over absolutes
The obesity epidemic • Where has it occurred? • Over what time period? • Explanations? • What have we been told to eat? • Is it working?
What happened in the 1960s? • Diet-Heart Hypothesis • Heart disease caused by saturated fat • Response: reduce fat (↑sugar or carb.) • Cheap sugar (HFCS) • American Heart Assoc.– spread to other English speaking countries Taubes G. The Diet Delusion. New York: Vermilion; 2007.
Laws of thermodynamics • A – B = C • A = Energy in (food) • B = Energy out (burned, exercise/basal metabolic rate) • C = Energy stored (as fat) • δA - environmental change (Coke ads/vending machines)
My thoughts on obesity Medical training Traditional Nutritional theory - Energy density Public Health Understanding addiction Research Similarities between obesity and smoking Research Critique of energy density Focus on sugar 1994 2005 2007 2011
Addiction? Automatic behaviour Rational behaviour e.g. Planning, Picking up children after work Addiction – Automatic, withdrawal, can’t stop, causes harm e.g. heroine Automatic behaviour? e.g. breathing Mid brain/brain stem Cortex
Negative re-inforcement Withdrawal discomfort Puff cigarette Nicotine metabolised Withdrawal relief More puffs
Eating and addiction? “Atkins Diet” An executive who had tried obesity surgery, laxatives, diets, everything… “Often I would shake until I could put some sugar in my mouth”
“I had an hour’s drive from my office to my home, and I knew every restaurant, every candy machine and every soft drink dispenser along the whole route.”
What about glucose? • Glycemic index very similar for glucose • Is carbohydrate the same as nicotine? • Is low GI a way out like nicotine patch or gum?
What about sugar? • Sugar is actually moderate GI
Brian Mckenna Big Sugar
What does the good book say? • “It is not yet clear whether any single attribute of the Western way of life is particularly important in increasing the risk of diabetes. Excess sucrose has largely been exonerated as an important dietary factor in the aetiology of type 2 diabetes...” • J. I. Mann and A. S. Truswell • Diseases of overnourished societies and the need for dietary change: in the Oxford Textbook of Medicine, 4th Edition.
Sugar – traditional views • 30% increase over last 30 years Popkin BM, Nielsen SJ. The sweetening of the world's diet. Obesity Research 2003;11(11):1325-32. • “empty calorie” Nestle M. Soft drink "pouring rights": marketing empty calories to children. Public Health Reports 2000;115(4):308-19. • Sucrose and other free sugars restricted to up to <15% of total caloric intake, due to excess energy and dental caries. Food and nutrition guidelines (Ministry of Health) 2003. • Fructose not mentioned
Average NZ consumption: • UN statistics (‘07)– 153g/day = 38 teaspoons/ day • 17% of total energy • Compare – 1961 – 33 teaspoons/day
Recent guidelines • American Heart Association 2002 Circulation 2002;106;523-527 • “No definitive evidence... Rely on professional judgement” • “Consuming fructose either free or in the form of sucrose has neither beneficial or adverse effects”
Brian Mckenna Big Sugar
Update... • “Originally proposed as the ideal sweetener for people with diabetes... Fructose... has been indirectly implicated in the epidemics of obesity and type 2 diabetes” Circulation 2009;120;1011-1020
Update • Upper limit set to reduce heart disease risk and maintain healthy weight • “6 teaspoons per day” for women • “9 teaspoons per day” for men
Health effects? • 1990s ADA encouraged diabetics to eat sugar/HFCS • 2000s about face due to ↑triglycerides • Small RCTs: • Rots teeth; raises triglycerides, ↓HDL, ↑BP, ↑urate. Johnson, R.J., et al., Hypothesis: Could Excessive Fructose Intake and Uric Acid Cause Type 2 Diabetes? Endocr Rev, 2009. 30(1): p. 96-116. Segal, M.S., E. Gollub, and R.J. Johnson, Is the fructose index more relevant with regards to cardiovascular disease than the glycemic index? European Journal of Nutrition, 2007. 46(7): p. 406-17.
Sugar - What has changed? • GI ignores fructose –Sugar half fructose (half glucose) • 4x as sweet as glucose • Links to gout, diabetes • Human studies limited, • Does not trigger satiety hormones→↑hunger • E.g. Insulin, CCK Johnson, R.J., et al., Hypothesis: Could Excessive Fructose Intake and Uric Acid Cause Type 2 Diabetes?Endocr Rev, 2009. 30(1): p. 96-116. Segal, M.S., E. Gollub, and R.J. Johnson, Is the fructose index more relevant with regards to cardiovascular disease than the glycemic index? European Journal of Nutrition, 2007. 46(7): p. 406-17.
Refined carbohydrate (high GI) • Reduced risk of chronic disease • Heart disease, cancer, gallstones. Barclay A, Petocz P, McMillan-Price J, Flood V, Prvan T, Mitchell P, et al. Glycemic index, glycemic load, and chronic disease risk—a metaanalysis of observational studies. Am J ClinNutr 2008;87:627-37 • Modest weight loss Thomas D, Elliott E, Baur L. Low glycaemic index or low glycaemic load diets for overweight and obesity. Cochrane Database of Systematic Reviews 2007;Art. No.: CD005105. DOI: 10.1002/14651858.CD005105.pub2(3).
What about saturated fat? • Meta-analyses now show no link between eating saturated fat and heart disease. Skeaff CM, Miller J. Dietary Fat and Coronary Heart Disease: Summary of Evidence from Prospective Cohort and Randomised Controlled Trials. Ann NutrMetab2009;55:173–201 Mente A, de Koning L, Shannon HS, Anand SS (April 2009). A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch. Intern. Med. 169 (7): 659–69.
Sugar and CHD? Sugar consumption Dental caries Coronary Heart Disease
Sugar addiction? • Yes in rats • Anecdote in humans
Food addiction-evidence Neural pathways (dopamine) Correlation between obesity & receptor density like other addictions Automaticity – serving size, availability Rise in sugar consumption worldwide over last 40 years. Rodents – sugar induces withdrawal; fat does not.
After the publicity... my inbox... • “For the first three weeks I cut all processed sugar and flour from my diet and suffered mood swings with extreme tension and depression, even a sense of hopelessness at times, I had horrible stomach pains, all my joints and muscles throbbed, and I had the shakes constantly.”
“I don't even know how to describe the horrible headaches that went along with all this. People who knew me started thinking I was hiding a drug problem.”
“The worst physical symptoms have been gone for about two weeks now, and the cravings are finally starting to subside… I look at birthday cake today and all I see is myself curled up in the foetal position crying in bed. “