This has certainly been the decade of jumping the sugar ship – and largely with good reason. The studies to illustrate what excess sugar can do to the body keep rolling in. And a new one in the journal Obesity goes a little further by trying to tease apart the difference between cutting out sugar and losing weight. It argues that sugar isn’t bad because it makes you gain weight. It’s bad because it brings about other, more sinister changes to the body – metabolic changes that are distinct from weight. Though this may be true, in part, weight certainly plays a role. So for the purposes of most of us, there may not be much reason to split hairs, since the takeaway hasn’t changed: Sugar is bad for us for multiple reasons, and cutting down on it is usually a good thing.
“This study definitively shows that sugar is metabolically harmful not because of its calories or its effects on weight; rather sugar is metabolically harmful because it’s sugar,” said study author Robert Lustig. “This internally controlled intervention study is a solid indication that sugar contributes to metabolic syndrome, and is the strongest evidence to date that the negative effects of sugar are not because of calories or obesity.”
The researchers studied the effects of sugar-restriction on 43 obese children, aged nine to 18, who had at least one other metabolic problem, like high blood pressure or high triglycerides (blood fats) or markers of fatty liver. For nine days, they ate a sugar-restricted diet, but their calories were kept as constant as possible, by substituting in starches and carbs for the sugars. The goal was to reduce sugar content in the diet from an average of 28% to 10%. But the team did not want the kids to lose weight – they wanted to keep weight constant while simply subtracting sugar from the diet, so see what would happen when this variable to changed but nothing else was.
At the end of the nine days, the kids’ metabolic parameters did shift significantly: Their average diastolic blood pressure decreased by 5 mmHg; their triglycerides were lowered by 33 points; their LDL (“bad”) cholesterol went down 10 points; insulin levels were reduced by a third, and fasting glucose and liver function tests improved.
“All of the surrogate measures of metabolic health got better, just by substituting starch for sugar in their processed food – all without changing calories or weight or exercise,” said Lustig. “This study demonstrates that ‘a calorie is not a calorie.’ Where those calories come from determines where in the body they go. Sugar calories are the worst, because they turn to fat in the liver, driving insulin resistance, and driving risk for diabetes, heart, and liver disease. This has enormous implications for the food industry, chronic disease, and health care costs.”
The study certainly confirms that reducing sugar can make a difference metabolically – and in a short period of time.
“Reducing the prevailing excess of sugar intake is associated with health benefits,” says David L. Katz, founding director of the Yale University Prevention Research Center, who was not affiliated with the new study. “That is shown here, and I certainly believe that to be true.”
But there’s a caveat. The researchers couldn’t keep the kids’ weight a stable as they’d hoped. There was an average trend to lose just under a kilogram over the course of the nine days.
“The researchers intended to keep weight stable, and could not,” says Katz. “Why? Presumably because sugar makes food more palatable to those habituated to the high levels that prevail in our culture, and replacing sugar with starch makes food less palatable. Many of the health effects seen here may as much a product of weight loss as they are a product of reduced sugar intake.”
But it may not matter why the kids got healthier, metabolically. That they got healthier, and by many measures, from cutting out sugar is the takeaway. “Whether reducing dietary sugar leads to health benefits mostly directly, mostly indirectly by means of weight loss, or both,” says Katz, “it leads to health benefits just the same.”
The researchers who conducted the study point out that even the kids who didn’t lose weight showed the same trend in metabolic measures. Though this may certainly have been the case, there are probably multiple ways in which cutting out sugar benefits health.
“When obese people lose weight, metabolic improvements occur with the weight loss, no matter what is causing it (even illness),” adds Katz. “But again, that means at worst that reducing sugar in the diet may help get kids to eat less and lose weight, and benefit accordingly. It may mean they benefit directly from the reduction in sugar, independent of calories and weight change. Personally, I think it’s a combination of both effects.”
So keep cutting down on sugar, especially added ones – and help your kids do the same. Whichever way it works, and there may be many, it does seem to work.