3 Knowledge alone is not enough Plenty of information about healthy diet and lifestyleIt is likely that many people are aware of ‘what they are supposed to eat’Survey in UK99% knew fruit and vegetables very or fairly important94% said eating less salt was important92% said limiting foods high in saturated fat was importantAwareness about healthy eating and lifestyle alone has not led to behaviour changePerhaps the key to behaviour change lies in better understanding the mechanisms behind behaviour itself?Food Standards Agency 2010
4 What factors influence behaviour? PhysicalPsychologicalIncludes knowledge & skillsReflective processesAutomatic processesSocialPhysicalMichie et al. 2011, Implementation Science 6:42
5 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.Larger, less certain and more distant rewards (e.g. losing weight, stay healthy)Environmental cues + power of immediate and certain pleasure (e.g. of eating chocolate)vs.Marteau 2011, BMJ 342: ; Atkins and Michie, Nutrition Bulletin 38:30-35.
6 Human behaviour shaped by two systems (Dual Process model) Reflective, goal oriented systemDriven by our values and intentionsRequires cognitive capacity or thinking spaceMany traditional approaches to health promotion target this system, i.e. designed to alter beliefs and attitudesAutomatic, affective systemRequires little or no cognitive engagementDriven by immediate feelings and triggered by environmentsStrack and Deutsch 2004, Pers Soc Psychol Rev 8:
7 Beyond awarenessAdults 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 awarenessThis is for a good reasonWould 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
8 Consumption normsPeople very easily influenced when it comes to how much they eatPlate size, package size, larger portions in restaurants, larger kitchen ware…They all suggest a certain ‘norm’ or portion sizePeople underestimate this influence and believe they are immune to themWansink 2010, Psychology & Behavior 100:
9 Are we aware of influence? 4 Experiments, intervention:A larger serving (double popcorn)Same serving, but in larger packageIntervention groups consumed 32% more than control groupOnly 8% thought they ate more than usual73% thought they ate about the same19% thought they ate lessWansink 2010, Psychology & Behavior 100:
10 Are we aware of influence? When told about the intervention and its effect52% claimed they did not eat more31% said if they did eat more it was because they were hungry15% gave other reasons (special occasion, it was free)Only 2% acknowledged it was because of the environmental cueThis means these determinants are not available for the processes of monitoring, reflection and goal-directed behaviour required for successful modificationMany people say “don’t know why they are so overweight since they hardly eat anything”Could be explained by fact that many determinants of food choice are beyond conscious awarenessWansink 2010, Psychology & Behavior 100:
11 The power of habitStrength of habit has a strong influence on behaviourHabit can even override taste (which itself strongly influences food choice)Habitual behaviour is more dependent on environment and less under conscious controlChadwick et al. 2013, Nutrition Bulletin 35:36-42;
12 The power of habit Fresh Stale Weak habit of eating popcorn in cinema Strong habit of eating popcorn in cinemaMeeting room contextCinemaMeeting room contextCinemaAte the similar amount of fresh and stale popcorn.Ate less when presented with stale than with fresh popcorn.Neal et al. 2011, Pers Soc Psychol Bull 37:
13 Nudging – a possible way to change behaviour Nudging means to change physical or social environment to make a certain behaviour more likelyMainly operates through the automatic, affective systemMarteau 2011, BMJ 342: ; Thaler and Sunstein: Nudge. Yale University Press 2008.
14 Does nudging work?Nudging works, although currently often used to drive unhealthy eating behaviourLimited evidence on nudges to encourage healthy behaviourCumulative nudges in a wide range of contexts may be required to be effectiveWithin enabling legislative and policy environmentsMarteau 2011, BMJ 342:
15 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 gainChernev 2011, J Cons Psych 21:
16 Which promotes more weight gain? Students and adults were presented with a variety of ‘healthy’ and ‘unhealthy’ snack options+vs.Chocolate569 kcal47 kcalOakes 2005, Appetite 44: ; Oakes 2005, Food Quality and Preference 16:
17 + The Dieter’s Paradox OR 14% kJ Chernev 2011, J Cons Psych 21:
18 Obesity is not a rational choice! ConclusionHow 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!