As part of the struggle against obesity, where the link between sugar and weight control is subject for debate, Institute Benjamin Delessert hosted an international conference last February 12th in Paris. The conference, chaired by Professor Bernard Guy-Grand (1), invited nine international experts to assess the current state of scientific knowledge on the topic.

Does sugar play a specific role in weight control? World-renowned experts ponder the question.

Weight gain is the result of an imbalance between energy intake and expenditure. The issue at stake is whether sugars present in liquid or solid food defeat food-intake, and incidentally weight, control mechanisms by creating passive consumption. Held on February 12th in Paris, the "Sugar and Weight Control" symposium surveyed the possible role of sugar in the overweight and obesity "epidemic".

Numerous interventions presented the complex nature that exists between "sugar and weight control". Talks given by world-renowned specialists approached the issue from a metabolic (metabolism of the various sugars, muscular energetic, the glycemic index / weight control relation) or epidemiological (analysis of data on sugar consumption and its impact on weight) standpoint. The following interventions focused on a behavioural and cognitive approach: the role of sugar in the food-intake control mechanism, the case of the sweet taste in acquired food preferences, the question of sweet-taste addiction, different social representations of sugar.

Conferences which contribute new elements of understanding

Here are a few preliminary elements of understanding on the complex relation between sugars and weight control gleaned from the interventions (2):

Sugar and weight: what does epidemiology teach us? Dr Alison Stephen (3) presented a detailed analysis of the data obtained from epidemiological literature associating sugar and the weight of populations. In those countries with relatively reliable data, sugar consumption did not increase over the past two decades, but food sources have changed. The results tend to show the lack of any link between sugar consumption and weight,

including in the case of sweetened beverages, for which there are fewer positive than negative correlations. Glycemic index, insulinemic index, and weight control. Tom Wolever (4) studied the ideas of glycemic and insulinemic indexes. Arguments drawn mostly from short-term studies lead to the conclusion that food with low glycemic indices fosters the maintenance of a stable weight by decreasing appetite. This effect is probably more closely related to other components than to the sugar content of such food.

Energy balance: is there any difference between sweet foods ingested in solid or liquid shape? Adam Drewnowski (5) considered the role of liquid foods, which might be less satiating than solid foods, thus resulting in a less controlled food intake. He underlined that as soon as the energetic density is the same, sweet liquids are as satiating as solid food. As regards the relation between sweet beverages and weight, he placed the blame on consumption behaviours rather than on sweet calories per se.

Role of sweet flavour in food-intake control. John Blundell (6) observed that the sweet taste is both a signal of energetic food and a source of pleasure and that - perhaps partly for genetic reasons - it has a pronounced effect on appetence. This effect is important if there is to be a desire to consume. However, there remain significant individual differences, based on sex and body fat, which do not allow overly general conclusions to be drawn.

Sweet-taste addiction: true or spurious debate? France Bellisle (7) stressed the importance of not misunderstanding the definition of addiction. She added that the excessive attraction for some foods (not necessarily sweet ones) may appear similar to a dependency on drugs because the mechanisms stimulated by the drugs are the same. Nevertheless, the fact remains that "sweet foods" may contribute to certain behaviour disorder, but not as a "drug" would". Generally, these disorders appear under specific circumstances (bulimia).

Conclusion: a necessarily varied answer

One certainty arises from the wealth of these conferences: the question of the role of sugar in weight control is so complex that it cannot be satisfied with a unique answer. The question of sugars and weight control deserves a multidisciplinary approach, integrating metabolic, epidemiological, behavioural and socio-cultural aspects, among others. The answer today must be varied: while sugars, through sweet foods, contribute to dietary intake, they cannot be blamed specifically for the obesity epidemic.

Institute Benjamin Delessert

The Institute Benjamin Delessert has helped Research since its creation in 1976, by financing studies bearing, among others, carbohydrate metabolism and physiopathology. The purpose of the Research Projects Awards, created in 2002, is to support academic research in France. "Benjamin Delessert Conferences" periodically gather several renowned lecturers to analyse a theme of current interest. http://www.institut-benjamin-delessert.org

CEDUS

The Information and Resource Centre on Sugar is a multidisciplinary agency, created in 1932: its mission is to provide information and documentation on an essential product of the French agro-food sector: Sugar.

http://www.lesucre.com

References

(1) Bernard Guy-Grand, Professeur Honoraire de Nutrition, Ancien Chef du Service de Nutrition, Hôtel-Dieu, Paris.

(2) A summary of lectures and a list of speakers are available on request.

(3) Dr Alison Stephen (PhD, Head of Population Nutrition Research at MRC Human Nutrition Research, Cambridge) UK.

(4) By Thomas MS Wolever, Department of Nutritional Sciences and Medicine, University of Toronto, Division of Endocrinology and Metabolism, St Michael's Hospital, Toronto, Canada.

(5) Adam Drewnowski - Center for Public Health Nutrition and the Nutritional Sciences Program, School of Public Health and Community Medicine, University of Washington, Seattle, WA 98195, USA

(6) John Blundell, Chair of Psychobiology, Institute of Psychological Sciences, University of Leeds, Leeds, LS2 9JT, UK

(7) France Bellisle, Institut National de la Recherche Agronomique (INRA), Centre de Recherche en Nutrition Humaine (CRNH - Île-de-France), SMBH, Bobigny France.

http://www.lesucre.com