Researchers: fructose is to blame for obesity

Nutrition experts have long been trying to identify the causes of obesity. The mission is challenging, despite appearances. There is much talk about the excessive intake of calories from certain foods, such as carbohydrates, fats, and the role of sugar. A team of American researchers is now proposing a unifying theory that brings together these seemingly contradictory ideas under a single common thread. Scientists believe they have discovered the potential culprit for the obesity epidemic: fructose.

According to the team led by Dr. Richard Johnson, a researcher at the Anschutz Medical Campus of the University of Colorado, fructose, found in table sugar and corn syrup, is at the heart of the obesity problem. Fructose can also be produced in the body from carbohydrates, especially from glucose. When the body metabolizes fructose, it reduces active energy known as ATP (adenosine triphosphate), which subsequently triggers hunger and increased food consumption. This concept, which researchers call the "fructose survival hypothesis," integrates various dietary theories related to obesity, including two that were previously contradictory: the energy balance theory, which assumes that excessive food intake, especially fats, causes obesity, and the carbohydrate-insulin model, which emphasizes the role of carbohydrates in weight gain. These theories, which previously seemed incompatible, can now be seen as pieces of a larger puzzle, united by a crucial component: fructose. "Essentially, these theories, which focus on a series of metabolic and dietary factors at the center of the obesity epidemic, are all pieces of a unified puzzle with a final piece: fructose," Dr. Johnson wrote in a university statement. Fructose is the trigger that causes metabolism to shift to low power mode and lose control of appetite, but fatty foods become the main source of calories that lead to weight gain, he explained.

To illustrate this unifying theory, researchers point to hibernating animals. When humans are hungry and lack sufficient active energy, the body goes into survival mode, just like animals preparing for winter by seeking food. Fruits, known for being rich in fructose, can significantly deplete active energy. Meanwhile, fats serve as stored energy. Consumption of fructose-rich foods prevents the replenishment of active energy from stored fats, leaving active energy levels low, similar to a bear preparing for a long winter hibernation. "This theory views obesity as a state of low energy," Dr. Johnson noted. Identifying fructose as the conduit that redirects active energy replacement to fat storage shows that fructose leads to an energy imbalance, uniting existing theories on obesity, he concluded. The study was published in the journal Obesity.