You’re likely referring to a study from the University of California, San Francisco investigating the effects of cutting sugar intake in children from 28 percent of daily calories to 10 percent. The authors reported dramatic differences in blood pressure, cholesterol levels, blood sugar and other signs of metabolic syndrome, a condition that increases the risk of diabetes, heart disease, and stroke. The 43 youngsters who took part were between the ages of 8 and 18, were obese and considered at high risk for diabetes. All were African-American or Hispanic and had at least one or more symptoms of metabolic syndrome.
The study team’s objective was to determine whether sugar itself – not excess calories – is responsible for the risks to health that constitute metabolic syndrome. They replaced sweetened foods such as pastries, flavored yogurt and other foods containing sugar in the kids’ diets with non-sweet, starchy carbohydrates including baked potato chips, bagels, turkey hot dogs or hamburgers that added up – in terms of calories – to the amount of sugar-laden sweets they had been eating. The researchers arranged for the “diet” food to be packed and distributed to each of the kids so that they would be getting the same number of calories they had been consuming when the they were eating sweets. Fresh fruit was the main source of sugar included on their nine-day diet.
Pediatrician Robert Lustig, M.D., who led the study, was quoted by Time magazine as saying his team deliberately didn’t give the kids healthy foods to substitute for the missing sweets. “We gave them crappy food…processed food – and they still got better. Imagine how much better they would have gotten if we didn’t substitute and took the sugar out. Then they would have gotten even better…”
After the nine days with less sugar, the findings were impressive. The kids’ LDL (“bad”) cholesterol had dropped by 10 points, their diastolic (the bottom number) blood pressure fell by five points, their triglycerides declined by 33 points. The investigators further reported that the kids’ fasting blood sugar and insulin levels, both of which can signal diabetes risk, also improved.
While these findings certainly suggest that sugar is responsible for increased risk of metabolic syndrome in obese kids, some other factors may also play a role. Although the study was designed to guard against weight loss in the youngsters – since dropping only a small amount of weight can have similarly beneficial effects on health – in fact, 77 percent of the kids did lose some weight. One expert quoted in news reports noted that even modest weight loss can make metabolic changes seem larger than they actually are. However, the researchers reported comparing the test results of the kids who lost weight with those who didn’t and seeing the same improvements.
Others criticized the fact that the study was uncontrolled – that is, there wasn’t a group of similar kids who continued to eat their regular diet for the nine days to compare with those who cut their sugar intake.
Although this study has generated a lot of interest, I doubt that it is the last word on this subject. But however you look at it, getting 28 percent of daily calories from sugar can’t be good for kids. Or adults.
Andrew Weil, M.D.
Richard M. Pulsford et al, “Associations of sitting behaviours with all-cause mortality over a 16-year follow-up: the Whitehall II study.” International Journal of Epidemiology, 2015; dyv191 DOI: 10.1093/ije/dyv191