Jan. 15, 2013 -- Eating less sugar is linked with weight loss, and eating more is linked with weight gain, according to a new review of published studies.
The review lends support to the idea that advising people to limit the sugar in their diets may help lessen excess weight and obesity, the New Zealand researchers conclude.
"The really interesting finding is that increasing and decreasing sugar had virtually identical results [on weight], in the opposite direction of course," says researcher Jim Mann, DM, PhD, professor of human nutrition and medicine at the University of Otago.
However, those studies have produced conflicting findings.
The new review is published in BMJ.
Sugar & Weight: The Studies
Since 2003, the World Health Organization (WHO) has recommended that intake of "free" sugars be limited to 10% of calories daily. The WHO is in the process of updating that recommendation, and it commissioned the review of this research to help that process.
Free sugars are defined as sugars added to foods by the manufacturer, cook, or consumer, or those naturally present in fruit juice, syrups, and honey.
In some of the studies evaluated, adults were told to lower their sugar intake.
Those who did lowered their weight slightly, Mann says. Over the course of the studies, which lasted for up to eight months, the average weight loss was about 1.7 pounds.
Adults who increased their sugar intake over the same average time period increased their weight nearly the same amount.
Over time, Mann says, that decrease (and increase) could be more. "There is also evidence that the longer the study, the more striking the effect," he says.
The link between sugar intake and weight was less consistent in studies of children, Mann found. He says that is mainly due to the kids not following the diet advice.
When they looked only at sugary beverages, however, the link between a sugary beverage habit and being overweight in children was strong.
Those who had the highest intake after a year were about 1.5 times as likely to be overweight or obese as those with the lowest intake, Mann found.