In the U.S., children often consume double or triple the amount the federal recommended guidelines for sugar intake, but cutting the amount of sweets that kids consume for as little as 9 days is all it takes for youngsters’ health to start improving, according to a new study from researchers at the University of California-San Francisco and Touro University.
For the study, 43 extremely obese youths, ages 9 to 18, were placed on low-sugar diets. Researchers extensively tested how their bodies changed during a little over week. The children or their parents completed a food questionnaire and were interviewed by a dietitian to develop a baseline diet which included a similar amount of protein, fat, and carbohydrates as their normal diet, but with 10 to 28% less sugar. The dietitian replaced the sugar with starch calorie-for-calorie.
The sugar removed from the kids’ diets was added sugar only. Naturally occurring sugar, such as the kind found in fruit, was considered acceptable. 
As you might expect from previously reading about the amazing effects of giving up sugar, the results of this test were not unexpected, but the rapid rate at which the children’s health improved was quite a shock. The children lost weight so fast during the study that scientists actually had to increase the number of calories they were feeding them.
At the end of the 9 days, the kids’ diastolic blood pressure had dropped, as did their LDL or “bad” cholesterol. Researchers saw drastic improvements in the participants’ glucose tolerance and the amount of excess insulin circulating in the blood.
Dr. Robert Lustig, professor of pediatrics at UC San Francisco School of Medicine and president of the Institute for Responsible Nutrition, worked with the group of researchers and wrote in an editorial in The Washington Post that he and his colleagues catered all of the meals for the participants, and that the children were welcome to eat processed “kid food” as long as there was no added sugar. They replaced chicken teriyaki with turkey hot dogs, sweetened yogurt with baked potato chips and pastries with bagels. 
Dr. Lustig wrote:
“In short, every aspect of their metabolic health improved: Their average diastolic blood pressure decreased by 5 mmHg, and their triglycerides (high levels of which are a risk factor for stroke) decreased by 33 percent. Their LDL cholesterol level and fasting blood glucose also fell, and their liver function tests improved — all without changing the children’s calorie intake or weight and without exercise. We simply substituted starch for sugar in their processed food and watched their health improve.
This is not correlation. It’s causation — the most robust evidence of all.”
The fact that the study participants’ health improved in spite of the salty chips and pretzels they were eating can be explained this way, according to Dr. Lustig: where a calorie comes from determines where a calorie goes and how the body will respond to it. Five-hundred calories worth of chips have a vastly different effect on the body than 500 calories worth of soda. 
Sugar calories turn to fat in the liver, which can lead to insulin resistance and a higher risk of diabetes, heart and liver disease. Even thin people can have metabolic syndrome, as evidenced by the high rates of diabetes in India and China, despite fairly low rates of obesity.
“The positive message is you can very quickly reverse a bad picture [of health] in a very simple way,” says Jean-Marc Schwarz, senior author of the study, which was published in the journal Obesity. “I have never seen results as striking or significant.”
Many lobbying groups have been pressuring the U.S. Food and Drug Administration (FDA) to require companies to list on product labels how much added sugar is in a product. The industry has resisted because it claims there is no scientific proof that sugar is harmful. This latest batch of research has done little to silence industry insiders.
The Sugar Industry Association – which represents major companies like Domino and C&H Sugar – calls the study “flawed,” arguing that since so many of the participants lost weight during the study, it’s “impossible to separate the effects of weight loss from dietary changes on the health variables measured.”
The group also says the lack of information the scientists provided concerning what the participants ate makes them question the legitimacy of the study’s hypothesis.
But as Dr. Lustig points out, Mars Incorporated candy company has embraced the U.S Dietary Guidelines Advisory Committee’s (DGAC) recommendation that people limit their sugar consumption, especially added sugar, to no more than 10% of their total daily energy and caloric intake. Mars announced in May that it would comply with the DGAC’s recommendation that food companies list added sugar on their products.