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Glycaemic index and body weight

Gary Frost

Imperial College

19902005

No Data <10% 10%–14% 15%–19% 20%–24% 25%–29% ≥30%

Percentage of people with a BMI over 30kg/m2

Change in nutrient intake over time

1000

1200

1400

1600

1800

2000

2200

2400

2600

2800

1943

1945

1947

1949

1951

1953

1955

1957

1959

1961

1963

1965

1967

1969

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

Years

En

erg

y (

Ka

cl/d

ay

)

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

60.0

Energy

Fat

CHO

Stable but mismatched genetic background

Increase GI

Decrease dietary fibre

What is glycaemic index

History

Known from the beginning of the century that different CHO have different effects on blood glucose and insulin

Early 1980’s Jenkins, Wolever and Leeds termed the phrase GI. Aimed at improving glycaemic control in people living with diabetes

Glycaemic response of carbohydrates

0

2

4

6

8

10

12

0 30 60 90 120

Time (minutes)

De

lta

ch

an

ge

in

glu

co

se

(mm

ol/l)

White Bread Wholemeal Bead White pasta Kidney beans

What is Glycaemic Index

Incremental area under the bloodglucose response curve for 50g of available carbohydrate from

test food

Corresponding area after equi-carbohydrate portion of glucose

X 100

Glycaemic indexFOOD

White bread

Wholemeal bred

Brown rice

White rice

Boiled potato

Pasta

Yam

Green banana

Sucrose

Baked beans

Chickpeas

GI bread

100

100

81

81

98

65

53

54

83

69

39

GI glucose

71

71

56

56

70

44

37

38

58

48

28

Glycaemic Index

Amount and type of

resistant starch

Degree of starch

gelatinisation

amylose to

amylopectin ratio

sugar

protein-starch and fat-

starch interactions

Physical form of food

fibre

fat

anti-nutrients

Physical form of food

Evidence in diabetes

Systematic reviewBrand-Miller 2004

0.4%

Model Group byDis

Study name Statistics for each study Rate ratio and 95% CI

Rate Lower Upper ratio limit limit Z-Value p-Value

Type 2 diab SalmeronF 1.37 1.09 1.72 2.74 0.01

Type 2 diab SalmeronM 1.37 1.02 1.84 2.11 0.03

Type 2 diab Schulze 1.59 1.21 2.09 3.30 0.00

Type 2 diab Hodge 1.36 0.95 1.95 1.68 0.09

Type 2 diab Zhang 1.30 1.00 1.68 1.98 0.05

Fixed Type 2 diab 1.39 1.23 1.57 5.33 0.00

Random Type 2 diab 1.39 1.23 1.57 5.33 0.00

0.1 0.2 0.5 1 2 5 10

Favours high GI Favours low GI

Meta-analysis of Low GI studies - Type 2 diabetes

Adjusted GI - validated studies only

Meta-analysis of observational studies

GI and diabetes risk (RR = 1.39)

Barclay et al. 2007, AJCN, in press

The evolution of Man…

Acute studies

Glycaemic response to foods: Impact on satiety and long-term

weight regulationFrancis R.J. Borneta etal Appetite 49 (2007) 535–553

19 studies covering 248 volunteers

12 supported an increase in satiety with low GI using VAS

4 out of the 7 studies using an objective method for satiety assessment

Effect of the glycemic index of carbohydrates on day-long (10 h) profiles of plasma glucose,

insulin, cholecystokinin and ghrelin

R C Reynolds etal 2008

Mean (±SE) breakfast and lunch self-reported hunger (A), fullness (B), and desire-to-eat (C) ratings obtained on a general labeled magnitude scale by 39 participants on days 1 and 8.

Alfenas R C , and Mattes R D Dia Care 2005;28:2123-2129

Copyright © 2011 American Diabetes Association, Inc.

Influence of Glycemic Index/Load on Glycemic Response, Appetite, and Food Intake in Healthy Humans Rita C.G. Alfenas, etal

Mean ± SE changes in plasma glucose (A), serum insulin (B), and hunger (C) after test meals.

Lennerz B S et al. Am J Clin Nutr 2013;98:641-647©2013 by American Society for Nutrition

Effects of dietary glycemic index on brain regions related to reward and

craving in men

Why is this different:GI difference 47 points different

Regions with significantly different cerebral blood flow 4 h after test meals (P ≤ 0.002).

Lennerz B S et al. Am J Clin Nutr 2013;98:641-647

©2013 by American Society for Nutrition

Cerebral blood flow was greater 4 h after the high-than low-GI meal in the right nucleus accumbens

right striatum down regulate dopamine and lead to overeating

Total glucagon-like peptide-1 (GLP-1), total peptide YY (PYY), dipeptidylpeptidase-4 (DPP-4) activity, blood glucose, and insulin in rats fed control diet (□) or resistant starch (RS) diet (▪)

ad libitum for 10 days in study 1.

Zhou J et al. Am J Physiol Endocrinol Metab 2008;295:E1160-E1166

©2008 by American Physiological Society

Long term

Weight loss

The study was based on a mean (±SD) difference in BMI of 1.2 ± 2.5, assuming 90% power and a 5% significance level. The needed total sample size was 148 (8). Allowing for non-compliance in both groups, the estimated sample size was 172; after further adjustment for an estimated 20% loss during follow-up, the total sample size was estimated to be 206.

Weight maintenance

Diogenes.

Larsen TM et al. N Engl J Med 2010;363:2102-2113.

The Effect of Dietary Glycemic Index on Weight Maintenance in Overweight Subjects: A Pilot Study

Obesity

Volume 17, Issue 2, pages 396-401, 6 SEP 2012 DOI: 10.1038/oby.2008.533

http://onlinelibrary.wiley.com/doi/10.1038/oby.2008.533/full#f1

What is going on?

Inulin and Appetite

Dietary NDCs have positive biological effects – mediated by SCFA

Increased concentrations of SCFA

Increased dietary NDCsIncreased fermentation

Increase anorexigenic signalling

Reduced appetite and food

intake

Reduced free fatty acid outputIncreased lipogenesisIncreased leptin secretionReduced inflammation

Increase inPYY & GLP-1

FFAR2/3 ??

FFAR2/3

Improved insulin sensitivity

Reduced cholesterol synthesisReduced glucose outputReduced inflammation

SCFA

FFAR2/3

Reduced inflammation

FFAR2/3

+

Change in gut flora

Conclusion

The effect of glycaemic index on appetite and body weight is a bit mixed.

But

Big differences show clear effects

High intakes of fermentable carbohydrate show effect

Need a fresh look with this insight.