Fructose, the simple sugar found in high-fructose corn syrup and table sugar, may do more damage to the body than other carbohydrates — and a new review published in a peer-reviewed journal suggests the mechanism runs deeper than just excess calories.
The review, reported by Healthline, found that fructose metabolism bypasses key regulatory steps in the body's energy processing pathways. That shortcut leads to increased fat synthesis, depletion of cellular energy, and the production of compounds linked to metabolic syndrome, a cluster of conditions that includes obesity, insulin resistance, and elevated cardiovascular risk.
Unlike glucose, which is processed throughout the body, fructose is routed almost entirely through the liver. Michelle Routhenstein, a preventive cardiology dietitian at EntirelyNourished, explained the problem plainly. "When it is consumed, it goes to the liver, where it easily turns into fat, which can build up in the liver and around the organs and contribute to conditions like fatty liver and metabolic syndrome," she said. Routhenstein was not involved in the study.
Fructose consumption has climbed sharply over the past few centuries, driven by the widespread use of sweeteners in packaged and processed foods. Part of what makes fructose difficult to moderate is its potency: it is roughly twice as sweet as glucose, which researchers say may fuel cravings for more fructose-containing foods and drinks.
The review also flags fructose's effects beyond metabolic syndrome. High intakes of concentrated fructose can raise uric acid levels and increase oxidative stress in the body. Routhenstein noted both findings, and certified nutritionist Serena Poon added that chronic, high-volume fructose exposure — particularly in liquid form — may also interfere with appetite regulation, satiety signaling, and gut barrier function.
"The emerging body of research suggests that fructose is not metabolically identical to all other carbohydrates, especially when it is consumed in excess through sugar-sweetened beverages and ultra-processed foods," Poon said. She was not involved in the study.
Poon was careful to frame the findings in context. Excess calories still matter, she said, but fructose may affect metabolism in ways that are distinct from other sugars, particularly in how the liver handles it. "In my view, this supports a more nuanced conversation — it is not just about sugar in the abstract, but also about the form, dose, and dietary context in which fructose is consumed," she said.
The review draws a distinction between fructose found naturally in whole fruits and honey and the concentrated forms used in processed food manufacturing. The strongest concerns, both researchers noted, are tied to patterns of habitual excess intake rather than to moderate consumption of naturally occurring fructose in whole foods. The authors suggest that understanding how fructose functions differently in the body could help develop new strategies for preventing and treating metabolic diseases.
