Healthy choices - University of Otago

Why is behaviour change so difficult to achieve? Dr Elisabeth Weichselbaum Nutrition Scientist and Consultant ewnutrition.net

Knowledge alone is not enough • Plenty of information about healthy diet and lifestyle • It is likely that many people are aware of ‘what they are supposed to eat’ • Survey in UK – 99% knew fruit and vegetables very or fairly important – 94% said eating less salt was important – 92% said limiting foods high in saturated fat was important Food Standards Agency 2010

What factors influence behaviour? Physical

Psychological Includes knowledge & skills

Reflective processes

Automatic processes

Physical

Social Michie et al. 2011, Implementation Science 6:42

Why is the healthier choice not always the easier choice? Our intentions and plans can only influence behaviour if they generate sufficiently strong wants or needs at the relevant moment to overcome competing wants or needs. Environmental cues + power of immediate and certain pleasure (e.g. of eating chocolate)

Larger, less certain and more distant vs. rewards (e.g. losing weight, stay healthy)

Marteau 2011, BMJ 342:263-265; Atkins and Michie, Nutrition Bulletin 38:30-35

Human behaviour shaped by two systems (Dual Process model)

Reflective, goal oriented system • Driven by our values and intentions • Requires cognitive capacity or thinking space • Many traditional approaches to health promotion target this system, i.e. designed to alter beliefs and attitudes

Automatic, affective system • Requires little or no cognitive engagement • Driven by immediate feelings and triggered by environments

Strack and Deutsch 2004, Pers Soc Psychol Rev 8:220-47.

Beyond awareness • Adults typically make more than 200 foodrelated decisions per day… • …but are aware of 14.4 food-related decisions. • Most of our food-related decisions are beyond conscious awareness • This is for a good reason – Would you get much done if you questioned all of your 200+ food-related decisions? Wansink and Sobal 2007, Env Behav 39:39-106; Chadwick et al. 2013, Nutrition Bulletin 35:36-42

Consumption norms • People very easily influenced when it comes to how much they eat • Plate size, package size, larger portions in restaurants, larger kitchen ware… • They all suggest a certain ‘norm’ or portion size • People underestimate this influence and believe they are immune to them Wansink 2010, Psychology & Behavior 100:454-463

Are we aware of influence? • 4 Experiments, intervention: – A larger serving (double popcorn) – Same serving, but in larger package

• Intervention groups consumed 32% more than control group – Only 8% thought they ate more than usual – 73% thought they ate about the same – 19% thought they ate less Wansink 2010, Psychology & Behavior 100:454-463

Are we aware of influence? • When told about the intervention and its effect – 52% claimed they did not eat more – 31% said if they did eat more it was because they were hungry – 15% gave other reasons (special occasion, it was free) – Only 2% acknowledged it was because of the environmental cue Wansink 2010, Psychology & Behavior 100:454-463

The power of habit • Strength of habit has a strong influence on behaviour • Habit can even override taste (which itself strongly influences food choice) • Habitual behaviour is more dependent on environment and less under conscious control Chadwick et al. 2013, Nutrition Bulletin 35:36-42;

The power of habit

Fresh

Stale

Weak habit of eating popcorn in cinema Meeting room context

Cinema

Strong habit of eating popcorn in cinema Meeting room context

Ate less when presented with stale than with fresh popcorn.

Cinema

Ate the similar amount of fresh and stale popcorn. Neal et al. 2011, Pers Soc Psychol Bull 37:1428-37

Nudging – a possible way to change behaviour • Nudging means to change physical or social environment to make a certain behaviour more likely • Mainly operates through the automatic, affective system

Marteau 2011, BMJ 342:263-265; Thaler and Sunstein: Nudge. Yale University Press 2008.

Does nudging work? • Nudging works, although currently often used to drive unhealthy eating behaviour • Limited evidence on nudges to encourage healthy behaviour • Cumulative nudges in a wide range of contexts may be required to be effective • Within enabling legislative and policy environments Marteau 2011, BMJ 342:263-265.

Healthier choice does not equal healthy weight • People tend to think of foods as either ‘good’ or ‘bad’ • Behave as though healthy foods have ‘halos’ – are perceived to be less likely to promote weight gain

Chernev 2011, J Cons Psych 21:178-183.

Which promotes more weight gain? Students and adults were presented with a variety of ‘healthy’ and ‘unhealthy’ snack options

Chocolate

47 kcal

vs.

+ 569 kcal

Oakes 2005, Appetite 44:317-324; Oakes 2005, Food Quality and Preference 16:447-454

The Dieter’s Paradox

+

OR 4000

14%

8%

3000 kJ 2000 Burger

1000

Burger plus celery sticks

0 Weight-concious individuals

Weight-indifferent individuals Chernev 2011, J Cons Psych 21:178-183.

Conclusion • How can we influence behaviour that lies outside awareness? • Could nudging work? • How can we avoid stereotype thinking about food?

Obesity is not a rational choice!