The weighty cost of added sugar

A calorie is not a calorie, according to a new study that found that a reduction in added sugar improved the health in 43 obese children over just 10 days.

Total caloric intake and activity levels were not changed in the study group, and the children were allowed to keep eating non-sugary snacks like potato chips. Researchers found that the children were satisfied with the diet; felt more full; lost weight; had better hepatic and renal function; and had lower blood pressure, blood glucose, and cholesterol from the change in sugar intake alone.

For pediatricians, this may lead to a shift in thinking about how to tackle metabolic dysfunction, says the report’s lead author.

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"Obesity is not about energy balance, it's about energy deposition. And the hormone that causes energy deposition is insulin. Yet, the standard mantra amongst providers remains, ‘If you fix the obesity, the metabolic dysfunction will improve.’ However no one can fix the obesity. It's really the opposite. If you fix the metabolic dysfunction, the obesity will improve. This is what we do in our clinic every day-get the insulin down,” says the report’s lead author Robert Lustig, MD, a pediatric endocrinologist and director of the Weight Assessment for Teen and Child Health (WATCH) Program at the University of California San Francisco. “Our study shows that sugar reduction-unrelated to calorie reduction-reduces hyperinsulinemia and improves metabolic health. Children are consuming almost 5 times their allotment of added sugar per day (19.5 tsp/d vs. 4 tsp/d). Sugar is not the sole cause of metabolic syndrome, but it is the most easily modifiable contributor. Reducing dietary sugar consumption should be the first step in pediatric obesity management."

The childhood obesity problem in the United States cannot be denied-it has doubled in children and quadrupled in adolescents over the last 30 years, according to the Centers for Disease Control and Prevention (CDC), and 17% of children and adolescents are not considered obese. While genetics, overconsumption of unhealthy foods, and inadequate activity are all in part to blame, Lustig and others have made it clear that sugar is a major factor in the epidemic.

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The American Heart Association recommends that men consume less than 9 teaspoons of added sugar each day and women less than 6 teaspoons, yet the average American consumes more than 22 teaspoons of added sugar-sugars that are not naturally occurring-each day. Children, on the other hand, should consume no more than 3 or 4 teaspoons a day of added sugar. Nearly half of the sugar consumed by children-an average of 15 teaspoons each day-is from sugary beverages and 20% comes from non-dessert sugary foods consumed at every meal, according to CDC.

The World Health Organization recommended limiting added sugar intake to less than 10% of total daily energy intake back in 1989 and recently affirmed that position, adding that further reduction to 5% would carry greater health benefits. According to the US Food and Drug Administration (USDA), Americans consumed about 35% of their calories from sugar, with soft drinks and other sweetened beverages claiming the largest portion of that consumption.

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Like the prevalence of chronic diseases, this over-consumption of added sugar is a modern-day problem. The USDA estimates that American now consume more than 110 pounds of added sugar each year, compared to a mere 2 pounds per year 200 years ago. The problem of hidden sugars has become so pronounced, that the USDA is now proposing the addition of a daily percent value for added sugars to nutrition facts labels. The agency is also due to released updated nutritional guidance later this year.

Lustig says physicians have never seen so many chronic diseases like non-alcoholic fatty liver disease, type 2 diabetes, dyslipidemia, and hypertension in children as they are seeing today. While they are more prevalent in obese children, these problems are occurring even in children of normal weight, according to the study, and are higher than in other countries.

Caloric intake is less to blame than the Western diet, which causes biochemical changes that promote insulin resistance and lead to a host of conditions collectively known as metabolic syndrome, according to the study.

Lustig says fructose is of particular concern, since it is metabolized in the liver; causes cellular dysfunction; and promotes excessive food consumption. For this study, researchers looked at the effects of sugar restriction with isocaloric substitution of complex carbohydrates. After adjusting the diets in the study group, the children were consuming 4% less carbohydrates, and 2% more protein, with no change in the number of calories from fat. Dietary sugars were reduced from nearly 28% to about 10%, and fructose from almost 12% to just under 4%. Fiber consumption was increased, too, but the diets still included a variety of low- or no-sugar processed foods and snacks like turkey hot dogs, pizza, baked potato chips, and popcorn.

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The intent of the study was to keep the weight of the study participants at baseline, but a weight loss of about 1% among participants was noted at the end of the 10-day study. Other changes included a heart rate decrease of 2.8 beats per minute; a 17.8 mmol/L drop in uric acid; and diastolic blood pressure decreases of 4.9 mmHg. Systolic blood pressure levels did not change over the 10-day study period. Fasting glucose decreased by 0.3 mmol/L and glucose area under the curve (AUC) dropped by 7.3%. Fasting insulin dropped by 53%; HOMA-IR decreased by 58%; peak insulin decreased by 56%; and insulin AUC dropped by 57%, according to the study. Additional, fasting triglyceride levels dropped by 46%, alanine aminotransferase dropped by 13%, and aspartate transaminase decreased by 3.6 U/L.

Previous studies have focused more on caloric consumption and weight loss in the management of chronic disease, but Lustig’s study reveals the negative effects of sugar-mainly fructose–on its own.

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“Concerns surrounding the role of sugar consumption in chronic disease have previously focused on its caloric equivalence and its role in fomenting increases in weight. Furthermore, previous clinical studies have relied upon excessive sugar administration, which introduces experimental artifact,” Lustig writes in his report. “This study mitigates all 3 of these concerns by intervening in children who are already sick with metabolic syndrome and by adjusting for effects of calories, weight gain, and adiposity. This study argues that the health detriments of sugar, and fructose specifically, are independent of its caloric value or effects on weight.”

Additional research will be needed to determine whether sugar restriction alone can serve as a long-term intervention for metabolic syndrome in adults.