Food addiction - does it exist?

1. Food addiction - does it exist? Suzanne Higgs School of Psychology University of Birmingham, UK

2. Why consider food addiction? Food addiction: a pervasive concept

3. Why consider food addiction?

4. Why consider food addiction? • Policy • Fat and sugar taxes • Limiting availability • Control of marketing • Treatment • Use of substance abuse approaches in the treatment of obesity • Screening for addiction in obesity programmes • Implications for dieting for weight loss

5. Why do some people think food addiction exists? • Food and drugs have similar effects on brain reward systems • There is overlap in the behavioural features of substance dependence and obesity • Evidence from animal models

6. Common brain reward systems Activation of brain dopamine systems and connected circuits by food and drugs underlies their rewarding effects Adapted from Kenny 2011

7. Drug addiction and obesity are associated with reduced dopamine D2 receptor availability From Volkow and Wise 2005

8. Issues • Drugs of abuse and food have different effects on dopamine systems • Different populations of neurons are stimulated by food and drug rewards (Carelli 2002) • The response to food but not drug rewards rapidly habituates (Roitman et al. 2004) • Not known what distinguishes an “addictive” food from a “non-addictive” food

9. Overlap in behavioural features From Volkow and O'Brien 2007

10. Clinical evidence • The Yale Food Addiction questionnaire (Gearhardt et. al. 2009) • A subset of obese patients scored highly on the YFA (Davis et al. 2011) • High scorers showed elevated brain activation to food cues in striatum (Gearhardt et al. 2011)

11. Issues • Some DSM-IV criteria translate well but for others the evidence is less clear • Tolerance? • Loss of control, restriction of activities and compulsion may apply more to binge eating than obesity

12. Evidence from animal models • Sugar addiction model (e.g. Avena, Rada and Hoebel 2008) • History of dieting and stress model (e.g. Hagan et al. 2002) • The limited access to palatable food model (e.g. Corwin and Wojnicki 2006)

13. Sugar addiction model • Intermittent access to glucose causes binge like behaviour • 12 hour access to normal diet and 25% glucose • 12 hours food deprived • Amount consumed in the first 1 hour is doubled after 20 days exposure (Colantuoni et al., 2001)

14. Cross sensitization Rats given intermittent sugar show greater response to amphetamine Avena and Hoebel 2003

15. Sugar addiction model: summary of findings

16. The limited access to palatable food model • Two groups of rats • time-limited access to palatable food every day • time-limited access a few times a week • Usually pure fat • Non-deprived – chow available at all times

17. The limited access to palatable food model Fat intake is increased after limiting access to 2 hours 3 times per week compared with 2 hours daily (Corwin et al. 1998) Intermittent fat binging increases responding for cocaine (Puhl et al. 2011)

18. Issues • Can replicate the conditions under which foods might act like drugs on the brain and behaviour • is this relevant to human eating situations? • Patterns of behaviour are important not specific food constituents • Animals do not gain weight in most models

19. Food addiction: does it exist? • Some people report problems with eating that resemble features of addiction • This may be due to patterns of consumption of palatable foods that alter brain reward systems • No clear evidence that specific foods are “addictive”

20. Food addiction: is it a helpful concept? • A focus on how diets affect brain function could be helpful for reducing stigma associated with obesity • Could learn from treatment approaches in addiction to help some people with eating problems • Personalizing treatment

21. Food addiction: is it a helpful concept? • Most people who are obese are not suffering from “food addiction” • Obesity is a heterogeneous condition with complex underlying causes • Notion that food is addictive may change our relationship with food • Focus on policies and treatments based on food addiction may ignore other approaches that could be more effective