School of Experimental Psychology University of...

Exposure to dietary sweetness with calories: Is there a learned association, and does sweetness without

calories impact food intake patterns and energy balance?

Peter Rogers

School of Experimental Psychology

University of Bristol

ILSI Europe Workshop, Brussels, 3-4 April 2017

Dietary Sweetness – Is It an Issue?

Disclosures

• I have received funding for research from Sugar Nutrition UK, provided

consultancy services for Coca-Cola Great Britain and received speaker’s

fees from the International Sweeteners Association.

• I will be referring to a systematic review and meta-analysis of effects of

low-calorie sweeteners on energy intake and body weight. This review was

initiated by ILSI-Europe, who also provided administrative support, hosted

meetings of the authors, and paid the academic authors travel expenses

and honoraria. Two of the eleven authors of the review are food industry

employees, and one was an ILSI-Europe employee.

Exposure to dietary sweetness with calories:

1. Is there a learned association?

2. Does sweetness without calories impact food intake and energy balance?

‘Consequently [as a result of consuming aspartame], individuals may receive

ambiguous signals for the control of appetite and ingestion.’ (Blundell & Hill, 1986,

p 1093)

‘We reasoned that if sweet tastes are normally valid predictors of increased caloric

outcomes, then exposing rats to sweet taste that is not associated with these

outcomes should degrade this predictive relationship and impair energy intake and

body weight regulation.’ (Swithers et al., 2010, p 56.)

Blundell & Hill (1986) Lancet, 327, 1092-1093

Swithers et al. (2010) Physiology and Behavior, 100, 55-62

1. Exposure to dietary sweetness with calories: is there a learned association?

1. Is there a learned association? Rats can learn associations between flavour cues and post-ingestive consequences of nutrients

Learned preference Learned satiety

1. Is there a learned association? Human beings can learn associations between flavour cues and post-ingestive consequences of nutrients

Appetite (2007) 49, 368-271

(1) ‘We reasoned that if sweet tastes are normally valid predictors of

increased caloric outcomes,

(2) then exposing rats to sweet taste that is not associated with these

outcomes should degrade this predictive relationship

(3) and impair energy intake and body weight regulation.’

(Swithers et al., 2010, p 56)

Swithers et al. (2010) Physiology and Behavior, 100, 55-62

1. Exposure to dietary sweetness with calories: is there a learned association?

1. Exposure to dietary sweetness with calories: is there a learned association?

Unsweetened yogurt 3 d/wk

Sweetened yogurt 3 d/wk Non-predictive (of additional calories) = Saccharin

OR Predictive (of additional calories) = Glucose

Rat chow ad libitum

Saccharin

Glucose

1. Exposure to dietary sweetness with calories: is there a learned association?

Swithers et al. (2010) Physiology and Behavior, 100, 55-62 Boakes et al. (2016) Appetite, 105, 105-128

(1) ‘We reasoned that if sweet tastes are normally valid predictors of increased

caloric outcomes,* [THIS IS NOT TRUE]

(2) then exposing rats to sweet taste that is not associated with these outcomes

should degrade this predictive relationship

(3) and impair energy intake and body weight regulation.’

*‘In nature, and throughout most of our evolutionary history, sweetness has been a

reliable predictor of the energy content of food.’ (Swithers et al., 2010, p 56)

Swithers et al. (2010) Physiology and Behavior, 100, 55-62

1. Exposure to dietary sweetness with calories: is there a learned association?

1. Is there a learned association? Sweet taste predicts the sugars but not the energy content of foods and drinks

1. Is there a learned association? Sugar content does not predict energy content of ‘natural’ foods

Some individual fruits Strawberry = 8 g sugar Blueberry = 14 g sugar Grape = 17 g sugar

Exposure to dietary sweetness with calories:

1. Is there a learned association?

2. Does sweetness without calories impact food intake and energy balance?

Repeated exposure to sweetness engenders preference for sweetness.

e.g., Mattes & Popkin (2009) American Journal of Clinical Nutrition, 89, 1-14 “In addition, overstimulation of sugar receptors by frequent consumption of hyper-intense sweeteners may cause taste preferences to remain in, or revert to, an infantile state (i.e., with limited tolerance to more complex tastes).”

Ludwig, D.S. (2009) Journal of the American Medical Association, 302, 2477-8 Yang, Q. (2010) Yale Journal of Biology

and Medicine, 83, 101-8

2. Does sweetness without calories impact on energy intake and energy balance?

Hypothetical results based Rogers et al. (2016) International Journal of Obesity, 40, 381-394

2. Does sweetness without calories impact on energy intake and energy balance?

‘Preload’

‘Test meal’ 1500 kcal served

Total energy intake

= <1 kcal

900 kcal

‘Preload’

‘Test meal’ 1500 kcal served

Total energy intake

= <1 kcal 150 kcal

‘Compensation’ = 50%

900 kcal 975 kcal

Hypothetical results based Rogers et al. (2016) International Journal of Obesity, 40, 381-394

2. Does sweetness without calories impact on energy intake and energy balance?

‘Preload’

‘Test meal’ 1500 kcal served

Total energy intake

= 0 kcal = <1 kcal 150 kcal

‘Compensation’ = 50%

900 kcal 975 kcal 900 kcal

Hypothetical results based Rogers et al. (2016) International Journal of Obesity, 40, 381-394

2. Does sweetness without calories impact on energy intake and energy balance?

Rogers et al. (2016)

International Journal of Obesity, 40, 381-394

2. Does sweetness without calories impact on energy intake and energy balance?

Preload, test-meal studies showed:

• Reduced energy intake after sweetness without calories (LCS) versus sweetness with calories (sugar)

Rogers et al. (2016)

International Journal of Obesity, 40, 381-394

2. Does sweetness without calories impact on energy intake and energy balance?

Preload, test-meal studies showed:

• Reduced energy intake after sweetness without calories (LCS) versus sweetness with calories (sugar)

• No effect on energy intake after sweetness without calories (LCS) versus no sweetness and no calories (water)

2. Does sweetness without calories impact on energy intake and energy balance?

Sustained intervention studies: effects of LCS versus sugar on body weight

Rogers et al. (2016) International Journal of Obesity, 40, 381-394

Rogers et al. (2016) International Journal of Obesity, 40, 381-394

2. Does sweetness without calories impact on energy intake and energy balance?

Sustained intervention studies: effects of LCS versus water on body weight

Repeated exposure to sweetness engenders preference for sweetness.

e.g., Mattes & Popkin (2009) American Journal of Clinical Nutrition, 89, 1-14 “In addition, overstimulation of sugar receptors by frequent consumption of hyper-intense sweeteners may cause taste preferences to remain in, or revert to, an infantile state (i.e., with limited tolerance to more complex tastes).”

Ludwig, D.S. (2009) Journal of the American Medical Association, 302, 2477-8

And/or Sensory-Specific Satiety?

Hetherington M.M. et al. (1989) The time course of sensory-specific satiety. Appetite, 12, 57-68.

Yang, Q. (2010) Yale Journal of Biology and Medicine, 83, 101-8

2. Does sweetness without calories impact on energy intake and energy balance?

Effect of consuming a non-sweet drink (water) versus sweet drink (low-calorie blackcurrant squash) on desire to consume apple juice, fresh apple and apple pie

Effect of Drink, p=.003 Effect of Stimulus, p=.002 Drink x Stimulus, F<1

Rogers et al., unpublished data

2. Does sweetness without calories impact on energy intake and energy balance?

Cross-over design Participants consumed the drink with a sandwich and with the subsequently presented Doritos (savoury) and chocolate chip cookies (sweet)

*p<.05, **p<.01, vs water

** *

Effect of consuming sweet drinks on sweet and savoury food intake

Rogers et al., unpublished data

2. Does sweetness without calories impact on energy intake and energy balance?

Participants randomised to choose water (n=106) or diet beverages (n=104) in place of sugar-sweetened beverages for 6 months.

Blundell and Hill (1986) Lancet, 327, 1092-1093

Increased appetite

‘Consequently [as a result of consuming aspartame], individuals may receive ambiguous signals for the control of appetite and ingestion.’

Exposure to dietary sweetness with calories: conclusions

1. Is there a learned association?

• There is no association to learn

2. Does sweetness without calories impact food intake and energy balance?

• Yes, when sweetness without calories (LCS) replaces sweetness with calories (sugars) it reduces energy intake and body weight

• No, sweetness without calories (LCS) versus water does not increase energy intake or body weight*

*This is a conservative conclusion, as accumulating evidence suggests that in some contexts sweetness without calories may reduce energy intake and body weight compared with water

Morenga et al. (2012) British Medical Journal, 345, e7492

Effect on body weight (kg) of iso-energetic exchange of free-sugars with other CHOs or other macronutrients

Sweetness and energy balance

Month 1: Baseline

Months 2-3:

Low-sugar diet group (n=13) replaced 40% of calories from simple sugars with fats, proteins and complex carbohydrates

Control group (n=16) did not change their sugar intake

Month 5: Both groups ate what they wished

Effect of reducing dietary intake of simple sugars on perceived sweet taste intensity and pleasantness

Wise et al. (2016) American Journal of Clinical Nutrition, 103, 50-60

Wise et al. (2016) American Journal of Clinical Nutrition, 103, 50-60

Effect of reducing dietary intake of simple sugars on perceived sweet taste intensity and pleasantness

Sweetness intensity Sweetness pleasantness

Sustained intervention studies: effects of low-calorie sweeteners on energy intake

• Low-calorie sweeteners versus sugar: -75 to -514 kcal/d (9 studies)

• Low-calorie sweeteners versus water: -126 kcal/d (1 study)

Rogers et al. (2016) International Journal of Obesity, 40, 381-394

Sustained intervention studies: further results

Blinding

• Outcomes were similar whether or not participants were ‘blinded’ to the intervention (i.e., whether they were aware or not aware they were consuming reduced calorie products)

Addition versus substitution • Outcomes were similar for studies in which (1) the test products were

added to the diet, compared with (2) when participants were already consuming sugar-sweetened products and the intervention was (partial) replacement of sugar with low-calorie sweeteners

Rogers et al. (2016) International Journal of Obesity, 40, 381-394