Study fails to isolate whether weight loss or calorie source was cause of health impact
In the recent study “Isocaloric Fructose Restriction and Metabolic Improvement in Children with Obesity and Metabolic Syndrome,” the authors allege that sugar, more specifically fructose, causes health-related problems that are independent of the health concerns related to intake of calories. However, the significant limitations of this research study warrant caution in developing conclusions and recommendations.
Most participants didn’t comply with research requirements
The study was originally designed to test whether substituting calories from starchy foods for the same number of calories from foods with sugar, specifically fructose, changes biomarkers related to cardiovascular health and glucose metabolism. Obese children were provided with 9 days of food intended to maintain each child’s body weight. However, more than 75% of the children participating in this study did not comply with the instructions and were unable to consume all of the food provided for weight maintenance. Therefore, the findings are not based on the question that the study was originally designed to evaluate.
Study skewed by substituting dietary fiber for sugar
Further, it is not surprising that blood pressure, lipid, and metabolism markers would change as obese children lose weight. However, this study cannot distinguish if improvements in biomarkers are due to the weight loss or dietary changes. While the diet modifications aren’t well described, the authors reported that restricting added dietary sugar was partly achieved by increasing dietary fiber. While both are carbohydrates, dietary fiber may specifically improve blood biomarkers differently than other carbohydrates and may not provide the same energy to the body as the original diet. While the authors attempted to research isolated effects of sugar as opposed to calories, the study was not conducted in a way to achieve this goal.
Conclusions from leading global research authorities differ with researchers
Nonetheless, numerous researchers have studied this question and the findings have been reviewed by authorities around the world. The Institute of Medicine of the National Academies (IOM), the European Food Safety Authority (EFSA), and most recently the Scientific Advisory Committee on Nutrition (SACN) in the United Kingdom concluded the relationship between dietary sugar and weight gain and body mass is related to the number of calories consumed — not the source of the calories. With this conclusion in mind, consumers concerned with their body weight should consider ways to limit dietary calorieswhile increasing physical activity.