Cutting sugar consumption pays off in weight loss for adults, while eating more produces weight gains, a new review that supports limits on intake has confirmed.
The weight-loss effect was small, an average of 0.8 kilograms or about 1.7 pounds, researchers in New Zealand conclude in this week's issue of the British Medical Journal.
The findings come as concerns mount worldwide about sugar intake and obesity. The World Health Organization, one of the study's funders, has said intake of free sugars should be less than 10 per cent of total energy intake. The review backs that strategy, the journal said in a release.
Lisa Te Morenga of the University of Otago and colleagues reviewed studies and randomized trials among adults that did not emphasize weight loss.
In the review, reduction of free sugars — those added by the manufacturer, cook or customer as well as those present in honey, syrup and fruit juice — was associated with weight loss in studies lasting up to eight months.
On the other hand, advice to increase intake was associated with about the same increase in weight, adding 0.75 kilograms or 1.6 pounds.
Body weight did not change when sugars were replaced with other carbohydrates.
The researchers said the relatively small effect isn't surprising considering the many causes of obesity.
Evidence was less consistent for children, who tended not to follow the dietary advice. But the risk of being overweight or obese increase among children consuming the most sugar-sweetened beverages compared with the least.
On Tuesday, officials in New York City said an upcoming ban on large, sweetened beverages will include a three-month grace period for restaurants and food service outlets before fines are issued.
A journal editorial accompanying the research called the sugar finding important but said recommendations on sugar intake should consider all health effects, not just fat. Consuming sugar and other carbohydrates raise blood glucose levels and drinking sugar-sweetened beverages has been associated with increased risk of Type 2 diabetes and heart disease.
The editorial called for measures including:
Reduced intake of refined grain products and potatoes.
Adding better quality food and drinks in schools and workplaces.
Reducing sugar consumed in drinks through taxes, restricting advertisements to children, and limits on serving sizes as enacted in New York City.
Having health care providers routinely ask about sugar sweetened beverage consumption.
Sugar in liquid form doesn't make people feel full the same way it does when solid, Walter Willett of the Harvard School of Public Health in Boston and David Ludwig, a pediatrics professor at Boston Children's Hospital, said in their editorial.
In a statement, the American Beverage Association said the study confirms that "it's calories that count when it comes to weight loss, not uniquely calories from sugar."
The editorial blamed overconsumption of sugar in part to sweetness itself.
"Food technologists exploit this fact to encourage greater consumption of these products," the pair wrote. "This results in a food supply that is permeated by a high level of sweetness, which may promote behaviours akin to addiction."
The University of Otago and Riddet Institute also funded the research.