portion size and weight control: insights from new
TRANSCRIPT
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
Increases in portion sizes in US and UK
Changing tableware
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
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
Results
• 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.
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
x% increase in size equates to x% increase in energy intake
Portion size effect is maintained over 2 days …
Rolls et al. (2006) JADA, 106(4): 543-549
… and onto 11 days
Rolls et al. (2007)Obesity, 15(6), 1535-1543
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, 543-549)
• Additional food does not increase sense of fullness (Rolls et al AJCN; 2002: 76, 1207-1213)
• 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, 242-245)
Smaller and larger sizes both ≥ 100% reference portion size: 81% (n=34).
Smaller size < 100% reference portion size and larger size > 100% reference portion size: 14% (n=6).
Smaller size < 100% reference portion size and Larger size = 100% reference portion size: 5% (n=2).
Reference portion size (100%)
Most studies have addressed the effects of larger (than reference) portion size
What happens to eating habits when portion sizes shrink?
?
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
.Prentice and Jebb
Nutr Rev. 2004 Jul;62(7 Pt 2):S98-104
Energy excess
Energy Balance
Energy deficit
Weaksatiety signals
Energy-dense dietsInactivity
Efficienthunger signals
Low-energy diets Exercise
Asymmetry of appetite control
A covert, randomised crossover study to test impact of smaller portions
Day prior to study day: overnight fast from 9pm
B – Portion size reduced by 20%
A – Regular portion size
Minutes 0
C – Portion size reduced by 40%
60 120 240 300 360
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
0 minutes- BreakfastEat in entirety
240 minutes– LunchAd libitum
360 minutes- SnackAd libitum
90 150 21018030
Lewis et al (2015). Obesity 23 (7): 1362-70
Study design
• Participants: 33 overweight and obese men (n = 15) and women (n = 18), mean BMI 29 kg/m2, mean age 43 years
• 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)
A
B
C
Lewis, Solis-Trapala and Jebb Obesity Facts, 6(suppl. 1), 139
Lewis et al (2015). Obesity 23 (7): 1362-70
Greater hunger and reduced fullness after smaller breakfast
Mean ± SEMLetter indicates the condition where the mean is
significantly different at that time
Lewis et al (2015). Obesity 23 (7): 1362-70
Reduced postprandial GLP-1 and GIP after smaller breakfast
Mean ± SEMLetter indicates the condition where the mean is
significantly different at that time
GLP-1 GIP
Lewis et al (2015). Obesity 23 (7): 1362-70
No significant differences in ad libitum energy intake at lunch…
Mean ± SEM
Lewis et al (2015). Obesity 23 (7): 1362-70
…or over the remainder of the day
Mean ± SEM
Lewis et al (2015). Obesity 23 (7): 1362-70
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-1 0.019 (0.071) 0.790 15.95 (11.17) 0.154
GIP 2.666 (4.446) 0.549 39.08 (33.06) 0.237
Glucose -0.916 (0.710) 0.197 -365.5 (245.8) 0.137
Insulin -197.0 (259.8) 0.448 -157.0 (168.7) 0.352
Do biochemical measures predict energy intake at lunch (fixed effects models)?
Lewis et al (2015). Obesity 23 (7): 1362-70
AUC as predictor Pre-lunch measure as predictor
Predictor of lunch EI Regression coefficient
(SE)
P value Regression coefficient
(SE)
P value
Appetite rating
Hunger 0.091 (0.022) <0.001 11.96 (3.934) 0.002
Fullness -0.029 (0.017) 0.085 -10.43 (3.389) 0.002
Desire to eat 0.087 (0.018) <0.001 8.788 (3.783) 0.020
Prospective
consumption
0.100 (0.022) <0.001 19.21 (4.384) <0.001
Predictor of whole
day EI
Regression coefficient
(SE)
P value
AUC appetite rating
Hunger 0.057 (0.025) 0.026
Fullness -0.016 (0.021) 0.469
Desire to eat 0.057 (0.023) 0.013
Prospective
consumption
0.068 (0.025) 0.007
Do appetite ratings predict energy intake at lunch and over the whole day (apart from breakfast); fixed effects models
Lewis et al (2015). Obesity 23 (7): 1362-70
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
0
2000
4000
6000
8000
10000
12000
A B C
Ener
gy in
take
(kJ
)
Condition
Reducing portions at breakfast leads to day-long reduction in energy intake
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
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”
November 11, 2015
Educating families: Me-size meals
What is an appropriate portion?
0
100
200
300
400
500
600
700
800
900
Min
i
Par
ty
Sna
ck
Sta
ndar
dKin
g
Gia
nt
kcal
20%female GDA
Using labelling to indicate appropriate portion size
Lack of consistency in suggested portion sizes
Muesli
• 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):2110-7.
What do we consider as ‘normal’?
Lewis, et al (2015) Int J Obes 39 (8): 1319-24.
Determining the portion size ‘norm’
Participants
Lean group (n = 30)
BMI = 22.7 (IQR: 21.7-24.3)
Age = 27 (IQR: 24-36)
Obese group (n = 30)
BMI = 32.1 (IQR: 31.2-33.4)
Age = 26 (IQR: 21-33)
0.5
0.7
0.9
1.1
1.3
1.5
1.7
Personal norm Social norm
Po
rtio
n s
ize
ind
ex
Lean
Obese
Obese have larger personal norms than lean
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
Personal norm Social norm
Po
rtio
n s
ize
ind
ex
Low restraint
High restraint
Those with lower restraint had larger personal norms
0.5
0.7
0.9
1.1
1.3
1.5
1.7
Personal norm Social norm
Port
ion
siz
e in
dex
Low liking
High liking
Those with greater liking, had larger personal norms
Lewis, et al (2015) Int J Obes 39 (8): 1319-24.
Norms are larger than suggested portion sizes
Lewis, et al (2015) Int J Obes 39 (8): 1319-24.
Norms are larger than reported portion sizes
Lewis, et al (2015) Int J Obes 39 (8): 1319-24.
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
• 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
Marteau, Hollands, Shemilt, Jebb. BMJ, under review
Fromeducation
To regulation
Through ‘Nudge’
Packaging has a powerful influence on norms
• 27 men (mean age 24.9 y; mean BMI 23.3 kg/m2)
• Portion size error greater when hungry than full (p<0.01)
• Trend towards greater error on larger serving sizes
63 g 427 g 140 g85 g150 g 80 g 520 g488 g
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
Po
rtio
n e
sti
ma
ted
(fa
ste
d)
Portion served (based on FSA)
Ice-creamCrisps
Hot choc.
Muffin Cornflakes
Choc.bar
Cola
Banana
Brogden & Almiron-Roig (2011) Public Health Nutrition
Reductions in portion size of iconic brands
Need to build public acceptability for some interventions
Portion size negatively correlated with choosing more than one bag (p = 0.003)Portion size positively correlated with consumption per diner (P = 0.001)
Freedman et al. 2010. Obesity 2010 Sep;18(9):1864-6.
Portion size (g/bag) Number of diners choosing
french fries
Mean ± s.d.
Consumption per diner
Mean ± s.d.(g)
88 315 ± 88 74.3 ± 2.2
73 348 ± 62 71.4 ± 2.4
58 359 ± 144 53.0 ± 2.5
44 377 ± 74 52.2 ± 6.0
Smaller portions in a canteen setting decrease intake of French Fries
A 50% decrease in portion size led to a 35% decrease in intake
23,373
24,847
19,027
19,604
Total weight served (g)
How small can you go without triggering compensatory responses?
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
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
Thank you for [email protected]