Portion size and weight control: Insights from new research and implications for policy and practice

Transcription

1 Portion size and weight control: Insights from new research and implications for policy and practice Professor Susan Jebb Nuffield Department of Primary Care Health Sciences University of Oxford

2 Increases in portion sizes in US and UK

3 Changing tableware

4 Systematic review: methods Randomised controlled trials comparing effects on energy intake of selection and consumption of different sizes of: - portions - packages - items of tableware used Hollands et al. Cochrane Database of Systematic Reviews 2015

5 Methods: Searches 11 electronic databases plus citation searching, trials registers and key websites Dual screening of 51,288 unique title and abstract records then 182 full-text reports. 72 studies met eligibility criteria and were included in analysis (with a further 11 identified in updated searches but awaiting full integration) Study data extracted and risk of potential bias systematically assessed

6 Results Intervention Outcome Comparisons Effect Larger size vs smaller size Consumption 92 from 61 studies (6711 participants) Small to moderate increase SMD: 0.37 (95% CI: 0.29 to 0.45) Moderate quality evidence IF sustained reductions in exposure to large sizes could be achieved across the whole diet, this could reduce average daily energy consumed from food by up to 16% among UK adults (equivalent of 279 kcals per day) or up to 29% among US adults (527 kcals per day) No evidence that size of effect varied substantively between men and women, BMI or tendency to control eating behaviour.

7 x% increase in size equates to x% increase in energy intake

8 Portion size effect is maintained over 2 days Rolls et al. (2006) JADA, 106(4):

9 and onto 11 days Rolls et al. (2007) Obesity, 15(6),

10 Portion size and energy intake Larger packets encourage selection of greater quantities of food (Wansink, J Marketing; 1996:60, 1-14) Larger portion sizes increase energy intake of that food (Rolls et al. JADA; 2006: 106, ) Additional food does not increase sense of fullness (Rolls et al AJCN; 2002: 76, ) Energy compensation at the next course, or subsequent meal is incomplete (Rolls et al. Appetite, 2004: 42, 63-69) Portion size effect is maintained, even if taste is poor (Wansink and Kim J Nutr Educ Behav, 2005: 37, )

11 Reference portion size (100%) Most studies have addressed the effects of larger (than reference) portion size Smaller size < 100% reference portion size and Larger size = 100% reference portion size: 5% (n=2). Smaller size < 100% reference portion size and larger size > 100% reference portion size: 14% (n=6). Smaller and larger sizes both 100% reference portion size: 81% (n=34).

12 What happens to eating habits when portion sizes shrink??

13 Immediate calorie savings Grande filter coffee with semi skimmed milk = 188 kcals Short filter coffee with semi skimmed milk = 95 kcals Saving = 93 kcals MacDonald BigMac burger = 540 kcals MacDonald cheese burger = 300 kcals Saving = 240 kcals Large Jamie Oliver carbonara penne = 930 kcals Small Jamie Oliver carbonara penne = 465 kcals Saving = 465 kcals

14 Asymmetry of appetite control Weak satiety signals Energy excess Energy-dense diets Inactivity Energy Balance Low-energy diets Exercise Efficient hunger signals Energy deficit. Prentice and Jebb Nutr Rev Jul;62(7 Pt 2):S98-104

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16 A covert, randomised crossover study to test impact of smaller portions 0 minutes - Breakfast Eat in entirety 240 minutes Lunch Ad libitum 360 minutes - Snack Ad libitum Day prior to study day: overnight fast from 9pm A Regular portion size B Portion size reduced by 20% C Portion size reduced by 40% Minutes Food intake Lunch and snack ad libitum eating occasions Intake over rest of day weighed diet diaries Biochemical Measures (n = 20) PYY, GLP-1 and insulin Perceived appetite using VAS questionnaires Appetite and mood ratings taken before and after consumption of meals and at half hourly time points Lewis et al (2015). Obesity 23 (7):

17 Study design Participants: 33 overweight and obese men (n = 15) and women (n = 18), mean BMI 29 kg/m 2, mean age 43 years B A Differences in energy intakes were compared using mixed models (fixed effect = condition, random effect = person) Hormone and perceived appetite profiles were compared using mixed effects model (fixed effects = interaction between condition and time, random effects = person and time) C Lewis, Solis-Trapala and Jebb Obesity Facts, 6(suppl. 1), 139 Lewis et al (2015). Obesity 23 (7):

18 Greater hunger and reduced fullness after smaller breakfast Mean ± SEM Letter indicates the condition where the mean is significantly different at that time Lewis et al (2015). Obesity 23 (7):

19 Reduced postprandial GLP-1 and GIP after smaller breakfast GLP-1 GIP Mean ± SEM Letter indicates the condition where the mean is significantly different at that time Lewis et al (2015). Obesity 23 (7):

20 No significant differences in ad libitum energy intake at lunch Mean ± SEM Lewis et al (2015). Obesity 23 (7):

21 or over the remainder of the day Mean ± SEM Lewis et al (2015). Obesity 23 (7):

22 Do biochemical measures predict energy intake at lunch (fixed effects models)? AUC as predictor Pre-lunch measure as predictor Predictor of lunch EI Regression coefficient (SE) P value Regression coefficient (SE) P value Biochemical measure GLP (0.071) (11.17) GIP (4.446) (33.06) Glucose (0.710) (245.8) Insulin (259.8) (168.7) Lewis et al (2015). Obesity 23 (7):

23 Do appetite ratings predict energy intake at lunch and over the whole day (apart from breakfast); fixed effects models Predictor of lunch EI Appetite rating Regression coefficient (SE) AUC as predictor P value Pre-lunch measure as predictor Regression coefficient (SE) P value Hunger (0.022) < (3.934) Fullness (0.017) (3.389) Desire to eat (0.018) < (3.783) Prospective consumption (0.022) < (4.384) <0.001 Predictor of whole day EI AUC appetite rating Regression coefficient (SE) P value Hunger (0.025) Fullness (0.021) Desire to eat (0.023) Prospective consumption (0.025) Lewis et al (2015). Obesity 23 (7):

24 Energy intake (kj) Reducing portions at breakfast leads to day-long reduction in energy intake Mean (± SEM) energy intake over the whole day according to condition. Dark shading: energy intake at breakfast, medium shading = lunch, light shading + remainder of day A B C Condition

25 Implications for public health strategies Covert portion size reduction of 40% was largely unnoticed Biological responses were evident in attenuated gastrointestinal hormone and perceived appetite profile. Subsequent energy intake was not significantly affected Consistency of later intake implies importance of habitual behaviour, at least in a highly controlled laboratory setting

26 Portion size messages for consumers Portion size recommendations: No specific guidance Often include generic statements, such as choose smaller portions Specific portion sizes often inconsistent Lack credibility with consumers Perceived as only relevant to dieters and diabetics watch your portions

27 Educating families: Me-size meals November 11, 2015

28 What is an appropriate portion? kcal % female GDA Mini Party Snack Standard King Giant

29 Using labelling to indicate appropriate portion size

30 Muesli Lack of consistency in suggested portion sizes Varied from 45g to 105g Meat Industry = 100g NGOs/HCPs = 74g Fat spreads Industry = 10g NGOs/HCPs = 5g Ice cream Industry = 2 scoops NGOs/HCPs = 1 scoop Lewis, Ahern and Jebb (2012). Public Health Nutr. 15(11):

31 What do we consider as normal? Lewis, et al (2015) Int J Obes 39 (8):

32 Determining the portion size norm

33 Portion size index Portion size index Portion size index Participants Obese have larger personal norms than lean 1.7 Lean group (n = 30) 1.5 BMI = 22.7 (IQR: ) Age = 27 (IQR: 24-36) Obese group (n = 30) Lean Obese BMI = 32.1 (IQR: ) Age = 26 (IQR: 21-33) 0.5 Personal norm Social norm Those with lower restraint had larger personal norms 1.9 Those with greater liking, had larger personal norms Low restraint 1.1 Low liking 1.1 High restraint High liking Personal norm Social norm 0.5 Personal norm Social norm Lewis, et al (2015) Int J Obes 39 (8):

34 Norms are larger than suggested portion sizes Lewis, et al (2015) Int J Obes 39 (8):

35 Norms are larger than reported portion sizes Lewis, et al (2015) Int J Obes 39 (8):

36 Suggested potential actions Targeting physical environment: (Labelling) Define and indicate appropriate portion size (Design) Demarcate portions in packaging through wrapping; Introduce tableware shapes that reduce effects of size (Proximity) Place larger sizes less accessibly (Size) Make default serving sizes or tableware smaller (Availability) Reduce availability of larger size options From education Through Nudge Targeting economic environment: (Appeal) Restrict pricing practices whereby larger sizes cost less in relative terms than smaller sizes and so offer more value for money; Restrict promotions on larger-sized packages To regulation Marteau, Hollands, Shemilt, Jebb. BMJ, under review

37 Portion estimated (fasted) Packaging has a powerful influence on norms men (mean age 24.9 y; mean BMI 23.3 kg/m 2 ) Portion size error greater when hungry than full (p<0.01) Trend towards greater error on larger serving sizes Banana Cola Choc.bar Hot choc. Muffin Cornflakes Crisps Portion served (based on FSA) Ice-cream 488 g 150 g 80 g 85 g 63 g 427 g 140 g 520 g Brogden & Almiron-Roig (2011) Public Health Nutrition

38 Reductions in portion size of iconic brands

39 Need to build public acceptability for some interventions

40 Smaller portions in a canteen setting decrease intake of French Fries Portion size (g/bag) Number of diners choosing french fries Mean ± s.d. Consumption per diner Mean ± s.d.(g) Total weight served (g) ± ± ± ± ± ± ± ± ,373 24,847 19,027 19,604 Portion size negatively correlated with choosing more than one bag (p = 0.003) Portion size positively correlated with consumption per diner (P = 0.001) A 50% decrease in portion size led to a 35% decrease in intake Freedman et al Obesity 2010 Sep;18(9):

41 How small can you go without triggering compensatory responses?

42 Portion size: from laboratory to policy Larger portions are associated with increased consumption and constitute a risk factor for weight gain Smaller portions may help limit overall energy intake Consumer awareness of appropriate portion sizes is poor and needs consistent messages to improve understanding, shape social norms and build acceptability of interventions Preliminary evidence that environmental changes to decrease portion size can reduce energy intake within a meal Pragmatic research studies needed to measure longer-term impact on eating behaviours and body weight in real-world settings to inform policy options

43 With thanks to: University of Oxford Paul Aveyard Nerys Astbury Jamie Hartmann-Boyce Sarah Morrish Carmen Piernas Sarah Tearne University of Birmingham Amanda Daley Kate Jolly Claire Madigan Sydney Helen Parretti MRC Human Nutrition Research, Cambridge Amy Ahern Eva Almiron-Roig Gina Ambrosini Perth David Johns Hannah Lewis Celia Walker Other Theresa Marteau, Cambridge Eric Robinson, Liverpool Peter Rogers, Bristol

44 Thank you for listening