Childhood obesity is one of the most pressing public health challenges facing the world today. According to the World Health Organization (WHO), the problem is global and is steadily affecting many low- and middle-income countries, particularly in urban settings. The WHO defines overweight and obesity as ”abnormal or excessive fat accumulation that presents a risk to health.” So, what are the health risks of overweight and obesity? The answer includes a long list of disorders, as for example cancer, reproductive problems, and metabolic syndrome.
Metabolic syndrome is the name for a group of risk factors that raises the risk for heart disease and other health problems, such as type 2 diabetes and stroke. Below is the list of the metabolic risk factors. A diagnosis of metabolic syndrome is usually made when at least three of these risk factors are present.
- A large waistline. This also is called abdominal obesity or “having an apple shape.” Excess fat in the stomach area is a greater risk factor for heart disease than excess fat in other parts of the body, such as on the hips.
- A high triglyceride level. Triglycerides are a type of fat found in the blood.
- A low HDL cholesterol level. HDL sometimes is called “good” cholesterol. This is because it helps remove cholesterol from the arteries. A low HDL cholesterol level raises the risk for heart disease.
- High blood pressure. If this pressure rises and stays high over time, it can damage the heart and lead to plaque buildup.
- High fasting blood sugar. Mildly high blood sugar may be an early sign of diabetes.
In the US, nearly 35% of all adults and 50% of those aged 60 years or older are estimated to have metabolic syndrome, a worrisome observation given the increasing aging US population. Metabolic syndrome also occurs in children, although only recently it has been identified as a condition of childhood obesity. Other diseases associated with metabolic syndrome, such as non-alcoholic fatty liver disease, now occur in children — this disorder, along with type 2 diabetes, was previously unknown in the pediatric population.
Consumption of drinks and foods with added sugars — and especially fructose, either as sucrose or high-fructose corn syrup — is linked to the development of metabolic syndrome. Dietary fructose is naturally present in fresh fruits — thus, many people think of fructose as a “healthier” alternative to other types of sugar. However, fruits contain very small amounts of this sugar. In contrast, fructose is present in much larger amounts in sweetened products such as sodas.
To ascertain whether or not cutting consumption of dietary fructose would improve metabolic syndrome in obese children, a group of researchers at UC San Francisco and Touro University California designed a study in which they modified the diet of 43 obese children, aged nine to 18, who had at least one other metabolic disorder — foods with added sugar were replaced with other carbohydrate-rich foods, such as bagels, cereal and pasta, so that the children’ weight and overall calorie intake remained about the same.
The study results were published online in the journal Obesity on October 27, 2015. After just 9 days on the sugar-restricted diet, virtually every aspect of the children’ metabolic health improved, without change in weight. Thus, the researchers concluded that the health detriments of sugar, and fructose specifically, are independent of its caloric value or effects on weight.
Robert Lustig, lead author of the study, said in a press release: “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.” He added: “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. This study demonstrates that ‘a calorie is not a calorie.’ Where those calories come from determines where in the body they go.”
Jean-Marc Schwarz, senior author of the study, said, “I have never seen results as striking or significant in our human studies; after only nine days of fructose restriction, the results are dramatic and consistent from subject to subject. These findings support the idea that it is essential for parents to evaluate sugar intake and to be mindful of the health effects of what their children are consuming.”
Interestingly, results from previous research show that fructose helps our brains to find high-calorie foods more appealing — in other words, it leads to overeating. In addition, excess fructose cannot be converted into energy by the mitochondria inside our cells. Instead, our cells turn excess fructose into liver fat, thus starting a cascade of insulin resistance that leads to chronic metabolic disease, diabetes and heart disease.