A new study from the University of Colorado School of Medicine suggests that the risk for obesity and insulin resistance may be related to fructose made by our body, along with fructose we consume in our diet.
In recent years, sweeteners such as high fructose corn syrup (HFCS) and table sugar (sucrose) have emerged as the prime suspects responsible for the epidemic of obesity and insulin resistance sweeping the U.S. Interestingly, many studies strongly suggest that the risk from added sugars may specifically be due to their extra fructose content.
In this study, mice were shown to convert glucose to fructose in their liver. This conversion was seen to be critical for driving the development of obesity and insulin resistance.
In other words, fructose made in the liver from glucose appears to be largely responsible for how carbohydrates cause fatty liver and insulin resistance. Health experts believe this may be the reason why high glycemic foods increase risk for obesity and insulin resistance.
The glycemic index (GI) is an estimate of how quickly blood sugar levels rise after eating a particular type of food, relative to the consumption of pure glucose which has a GI of 100. The effects that different foods have on blood sugar levels vary considerably and are not always easy to predict.
High GI foods will release more glucose into blood upon consumption, which means the liver will make more fructose - raising the risk of obesity and insulin resistance. While some of the weight gain is driven by caloric content and the effects of stimulating insulin, the ability of high GI foods to cause insulin resistance and fatty liver is at least partly due to the conversion of glucose to fructose in the liver.
Ironically, this study shows that much of the risk from ingesting high GI foods is actually due to the generation of fructose, which is a low GI sugar. It challenges the existing belief that fructose is safe - and that it is simply the high GI carbohydrates that need to be restricted in our diet for weight loss and overall health.
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