Cutting most of the sugar from a child’s diet can rapidly and dramatically improve health, even without reducing calorie consumption or losing weight, a new study suggests.
Researchers put a group of 43 obese kids and teens on a nine-day diet that severely restricted sugar intake, but replaced added sugars with starchy foods to maintain the children’s intake of calories and carbs. That diet caused immediate reductions in their high blood pressure and improvement in their blood sugar and cholesterol levels, the investigators reported in a paper published online ahead of print in the medical journal Obesity.
“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 lead author Robert Lustig, M.D., MSL, pediatric endocrinologist at UC San Francisco’s Benioff Children’s Hospital. “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 study is part of a growing body of research showing the negative health effects of the roughly 22 teaspoons of sugar Americans eat or drink each day, mostly from sodas and processed foods. The increasing awareness of how sugar affects the body has prompted changes to the food industry, including labeling requirements and efforts to tax or legislate the size of sugary drinks. This year, Berkeley, CA, became the first city in the country to levy a tax on sugar-sweetened beverages. Studies suggest that taxing sugary drinks is among the most effective of all anti-childhood-obesity policies.
Participants in this latest study, ages 9 to 18, were selected through the Weight Assessment for Teen and Child Health Clinic (WATCH), a UCSF program that concentrates on improving metabolic health rather than reducing weight. The researchers limited recruitment to African American and Latino youths because of their disproportionately high rates of metabolic syndrome, a cluster of conditions — high blood pressure, high blood glucose levels, excess abdominal fat, and elevated cholesterol levels — that occur together and increase the risk of heart disease, stroke and diabetes.
Upon enrollment, all participants underwent extensive testing that included everything from basic blood pressure measures and cholesterol counts to oral glucose tolerance tests and sophisticated bone density scans. Next, the children (or their parents) filled out a food questionnaire and were interviewed by a dietitian to come up with a baseline diet (an approximation of the child’s typical eating habits).
The scientists then designed a new diet that included a similar amount of protein, fat, carbohydrates, and calories as their usual diet, but cut back on added sugar. The goal here was to isolate the effect of added sugars on the children’s metabolism, keeping all other dietary inputs equal. To keep carbohydrate and caloric intake at the same levels while also reducing added sugars, the researchers replaced sugars with starches, calorie for calorie.
Food choices were still designed to be ‘kid-friendly’ — not exactly your typical health foods — but instead of high-sugar foods like pastries and sweetened yogurt, the children were offered other processed foods such turkey hot dogs, bagels, pizza and baked potato chips, which contain carbs in the form of starches, not added sugars. Sugar-sweetened beverages, including fruit juice, were not allowed. These dietary changes reduced kids’ average sugar intake from 28 percent of total calories to 10 percent, in accordance with current World Health Organization guidelines.
‘Dramatic and consistent improvements’
The transformation in the kids was almost immediate.
“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 Dr. Lustig.
After just nine days, the kids showed marked improvements across multiple key indicators of health: Diastolic blood pressure (the bottom number) dropped an average of 5 points, triglycerides (fat in the blood) dropped 33 points, LDL (the “bad” cholesterol) went down 10 points, and liver function tests improved. In addition, fasting blood glucose (sugar) went down five points and insulin levels were cut by a third, signaling improved glucose tolerance and decreased risk of diabetes.
The magnitude and consistency of these improvements were so remarkable that even the researchers were surprised by their findings. “I have never seen results as striking or significant in our human studies,” said senior author Jean-Marc Schwarz, Ph.D., a professor in the College of Osteopathic Medicine at Touro University California. “After only nine days of fructose restriction, the results are dramatic and consistent from subject to subject.”
Furthermore, even though participants were still eating roughly the same amount of calories, many ended up losing weight — an average of one percent of their body weight in that short period of time. Several of the children lost so much weight so quickly that the researchers had to increase the number of calories they were feeding them in an attempt to help stabilize their weight.
While surprised by the results, Dr. Schwarz said his previous research has indicated the body responds rapidly to short-term sugar reduction. He found similar results in a study released this year on a small group of normal to moderately overweight adult men.
Sugar calories ‘worse than other calories’
One of the key questions the researchers were interested in answering was whether restricting dietary sugars in children with metabolic syndrome would lead to the metabolic dysfunction resolving. The study seems to have answered that with a preliminary ‘yes’.
By isolating the effect of sugar on metabolic function (through dietary planning and weight maintenance), the researchers can say with more confidence that the observed health benefits are attributable to cutting back on sugar intake, not some other dietary change. Additionally, if the children had lost significant amounts of weight, the improvements in their blood sugar and other measures could be attributed to the weight loss, not the sugar restriction, the researchers said. Although some of the kids did experience slight weight loss, there were no differences in health outcomes between those who lost weight and those who didn’t, and a regression analysis confirmed that weight-loss did not contribute significantly to the improvements in kids’ metabolic health.
The findings raise serious concerns about the health effects of sugar, and call into question the longstanding belief that all calories are the same, regardless of the food source, said Dr. 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,” he said.
Dr. Lustig also pointed out that not all sugars are the same, either, and some are much more harmful than others. The sugar contained in foods is made up of two simple sugars called glucose and fructose, and studies have found that fructose can promote cellular aging, along with a host of other adverse physiological effects. According to Dr. Lustig, fructose is “one of the most egregious components of the western diet, directly contributing to heart disease and diabetes, and associated with cancer and dementia” 3e4wFructose also acts directly upon the reward system in a person’s brain, causing them to crave more sugar and creating a vicious cycle in which sugar cravings lead to increased sugar intake, which in turn worsens cravings and reinforces the maladaptive eating pattern.
The bottom line? Sugar in large amounts is definitely associated with weight gain, and we can be pretty certain that it’s also an independent risk factor for diabetes and metabolic and heart disease. Reducing it (even without intentional caloric restriction) usually leads to weight reduction, and to improved health outcomes. So cutting out added sugar and aiming for the World Health Organization‘s and the American Heart association‘s target of no more than 6 teaspoons a day for women, 9 teaspoons a day for men, is very sound advice. The first step towards that not-easy-to-achieve goal is to know how much sugar is added to our food, which is what’s proposed by the FDA, and being fought mightily by the food industry.