LONDON -- Increasing or decreasing intake of sugar is associated with changes in body weight, a commonly held view confirmed by the first systematic review of available evidence commissioned by the World Health Organization.
Increased consumption of so-called free sugars -- including additives to foods and those naturally present in honey, syrups and fruit juices -- led to an average gain of 0.8 kilograms (or 1.8 pounds) in body weight in adults, University of Otago researchers in New Zealand found in a review of 71 studies. Limiting the analysis to studies lasting longer than eight weeks, weight gain was 2.7 kilograms (or 6 pounds), they said.
The WHO commissioned the review in preparation for updating its 2003 recommendation that free sugar be limited to less than 10 percent of energy intake. The study adds to a debate over public policy aimed at curbing the obesity epidemic and related diseases, including New York City's decision to restrict sales of large-sized sugary soft drinks.
"When considering the rapid weight gain that occurs after an increased intake of sugars, it seems reasonable to conclude that advice relating to sugars intake is a relevant component of a strategy to reduce the high risk of overweight and obesity in most countries," the authors said in a paper published Wednesday in the British Medical Journal.
Cutting consumption of sugars led to an average 0.8-kilogram reduction in weight in adults, according to five studies that ranged from 10 weeks to eight months, the authors said. Among studies in children, comparison of varying levels of consumption suggested a "significantly increased risk" of being overweight associated with higher intakes, they said.
"This review clearly indicates the positive association, which I think is quite striking, given that no such systematic reviews have been conducted so far," Chizuru Nishida, a coordinator in the WHO's Department of Nutrition for Health and Development in Geneva, said in an interview. The study defends the current WHO guidelines that have been criticized as having no scientific basis, she said.
The WHO has commissioned a second study, to be published sometime in the next few months, looking at sugars and tooth decay and will consider both analyses in its updated recommendation, Ms. Nishida said.
"Reducing the amount of sugar consumed in drinks deserves special attention because of the strength of the evidence and the ease with which excessive sugar is consumed in this form," said Walter Willett, a Harvard School of Public Health professor, and David Ludwig, a Boston Children's Hospital professor, in an editorial accompanying the study. "But questions remain. What is a desirable limit?"
In September, New York City's Board of Health approved Mayor Michael Bloomberg's plan to restrict sales of sugary soft drinks to no more than 16 ounces (450 grams) a cup. They rejected arguments from Coca-Cola Co., PepsiCo Inc. and restaurant companies whose coalition says the issue is about consumers' freedom to choose. The mayor is founder and majority owner of Bloomberg News parent Bloomberg LP.