Why is behaviour change so difficult to achieve?

Dr Elisabeth WeichselbaumNutrition Scientist and Consultantewnutrition.net

• 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

Knowledge alone is not enough

Food Standards Agency 2010

What factors influence behaviour?

Michie et al. 2011, Implementation Science 6:42

Physical Psychological

Includes knowledge & skills

Reflective processes

Automatic processes

Physical Social

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.

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

Environmental cues + power of immediate and certain pleasure (e.g. of eating chocolate)

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

vs.

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 food-related 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

• 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

Are we aware of influence?

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

Neal et al. 2011, Pers Soc Psychol Bull 37:1428-37

Fresh Stale

Strong habit of eating popcorn in cinema

Weak habit of eating popcorn in cinema

Meeting room context Cinema Meeting room context Cinema

Ate less when presented with stale than with fresh popcorn.

Ate the similar amount of fresh and stale

popcorn.

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.

Chocolate

47 kcal

+569 kcal

Which promotes more weight gain?

vs.

Students and adults were presented with a variety of ‘healthy’ and ‘unhealthy’ snack options

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

The Dieter’s Paradox

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

+OR

Weight-concious in-dividuals

Weight-indifferent individuals

0

1000

2000

3000

4000

BurgerBurger plus celery sticks

8%14%

kJ

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!