A review published in Nature Metabolism on April 17, 2026, by researchers at the University of Colorado Anschutz makes a case that fructose, the sweetener in table sugar, high-fructose corn syrup, and most processed food, is not simply another source of calories.
It is a metabolic signal, and that signal tells your body to store fat through mechanisms that are fundamentally different from how glucose works.
The lead author, Dr. Richard Johnson, professor at the University of Colorado Anschutz, stated it plainly.
“Fructose is not just another calorie,” he said. “It acts as a metabolic signal that promotes fat production and storage in ways that differ fundamentally from glucose.”
Here is what the research says, what it means, and what experts recommend doing about it.
The Basic Difference Between Fructose And Glucose
Both fructose and glucose are simple sugars. Both contain the same number of atoms and the same caloric value per gram. On a nutrition label they look identical. In your body they behave very differently.
Glucose is the body’s primary energy currency. When you eat glucose, it is distributed to cells throughout your body, muscles, brain, organs, where it is used for energy through tightly regulated pathways.
Insulin facilitates this process and also signals satiety, letting your brain know that energy has arrived and you can stop eating.
Fructose takes a different route. It is metabolized almost entirely in the liver, bypassing the regulatory checkpoints that govern how glucose is processed.
It does not trigger insulin release. It does not signal fullness. The liver receives fructose and converts it to fat, specifically to triglycerides, more readily than it converts glucose.
And because fructose does not produce the same satiety signals that glucose does, you can consume a meaningful amount of it without your body registering that it has received energy.
Certified holistic nutritionist Robin DeCicco explained the liver burden directly in an interview with Fox News Digital.
“Unlike glucose, fructose metabolism can make the liver turn the sugar into fat more easily,” she said. “Triglycerides are fat deposits in the arteries.”
She added that the increased fat buildup caused by fructose can then interfere with insulin signaling, contributing to the insulin resistance that sits at the center of type 2 diabetes.
What Fructose Does Inside The Body
The Nature Metabolism review lays out several distinct mechanisms by which fructose contributes to disease, each one operating differently from the caloric impact that conventional nutritional thinking would predict.
The first is triglyceride synthesis. When fructose arrives in the liver in large quantities, it accelerates lipogenesis, the process by which the liver builds fat.
This fat enters the bloodstream as triglycerides and can accumulate in the liver itself, contributing to non-alcoholic fatty liver disease. Elevated triglyceride levels are an independent risk factor for cardiovascular disease.
The second is ATP depletion. ATP is the molecule that stores and transfers energy within cells, think of it as cellular fuel. Fructose metabolism consumes ATP rapidly in the liver, creating a localized energy deficit.
That energy deficit sends signals to the brain that the body needs more fuel, even if plenty of calories have just been consumed.
This may be one reason why foods high in fructose drive overeating, not through any psychological mechanism, but through a straightforward cellular signaling effect.
The third is uric acid production. Fructose metabolism generates uric acid as a byproduct.
Elevated uric acid is associated with gout, kidney disease, and hypertension.
The researchers describe it as both a biomarker and a mediator of fructose-induced metabolic damage, meaning it is not just a warning sign but an active contributor to the harm.
The fourth is interference with insulin signaling. As fat accumulates in liver cells and muscle tissue, the body’s ability to respond to insulin degrades. Insulin resistance is the defining characteristic of type 2 diabetes and a central feature of metabolic syndrome.
Fructose contributes to this through fat accumulation, not through any direct effect on insulin secretion.
The Part Nobody Expected: Your Body Makes Its Own Fructose
The most surprising finding in the review, and the one that explains why the paper describes fructose’s role as bigger than previously assumed, is the internal fructose pathway.
Your body can produce fructose from glucose. The conversion happens via a biochemical route called the polyol pathway, and the paper describes this as a previously underappreciated contribution to fructose’s disease impact.
This means that even people who are careful about limiting fructose in their diet may be generating it internally, particularly if they eat large amounts of carbohydrates, salty foods, or alcohol, all of which provide substrate or amplify the conversion pathway.
The implication is significant. It suggests that fructose’s role in metabolic syndrome may not be limited to people who drink soda and eat processed food.
Anyone eating a high-carbohydrate diet in conditions of overnutrition may be generating meaningful amounts of fructose internally and experiencing the downstream effects.
The Evolutionary Explanation
The researchers offer an evolutionary framework that helps explain why human biology responds to fructose this way.
In early human environments, fructose was rare, found mainly in ripe seasonal fruit.
When fructose was available, it was a reliable signal that summer had arrived, food was plentiful, and the body should prepare for leaner times by storing energy as fat. Fructose’s fat-promoting effects were adaptive. They helped our ancestors survive winters.
In a modern food environment, that ancient signal fires constantly. High-fructose corn syrup was introduced into the American food supply in the 1970s.
Since then, obesity rates have tripled and diabetes diagnoses have risen sharply.
The paper does not argue that fructose alone caused this, but it does argue that the biological machinery that once served survival is now, under conditions of constant food availability and persistent overnutrition, contributing to chronic disease.
The Diseases Linked To Fructose
Beyond metabolic syndrome, the cluster of conditions including abdominal obesity, high blood pressure, elevated blood sugar, high triglycerides, and abnormal cholesterol, the paper cites emerging evidence connecting fructose to a broader range of conditions.
Fructose’s ability to deplete ATP and interfere with normal cellular metabolism may fuel tumor growth, according to the paper’s review of cancer research.
Fructose’s effects on brain energy metabolism and hunger hormones have been linked in emerging studies to increased dementia risk.
Uric acid accumulation contributes to kidney disease. Gut dysfunction and systemic inflammation are also cited as downstream effects of chronic fructose exposure.
The authors are careful to note that much of this evidence is still emerging and that individual responses to fructose vary based on gut microbiota composition, enzymatic activity, hepatic function, and genetic factors.
This is a review paper, not a new clinical trial, it synthesizes existing evidence rather than proving new results.
That is a meaningful limitation. But the pattern of evidence the paper describes across multiple mechanisms and multiple disease outcomes is consistent and substantial.
What To Do About It
The practical question for people reading this research is what to actually change. DeCicco and the study itself offer some concrete guidance.
The highest-risk form of fructose is liquid fructose in sugar-sweetened beverages, sodas, sweetened teas, fruit drinks, energy drinks.
Liquid fructose is absorbed faster, arrives in the liver in higher concentrations, and has the strongest demonstrated link to metabolic harm.
Eliminating or substantially reducing sugary beverages is the single most impactful dietary change for anyone concerned about fructose.
Whole fruit is a different situation. Yes, fruit contains fructose, but it also contains fiber, which dramatically slows absorption and reduces the liver burden. It contains antioxidants, vitamins, and minerals.
The paper and the experts interviewed treat whole fruit as categorically different from processed fructose. The goal is not to stop eating apples. The goal is to stop drinking apple juice.
For people who need to bake or want something sweet and have specific metabolic concerns, liver disease, obesity, diabetes, DeCicco points to several alternatives.
Stevia and monk fruit are natural sweeteners with no fructose content. Maple syrup has less fructose than honey. Rice malt syrup and glucose syrup contain zero fructose.
These are not suggestions for everyone, but for people actively managing metabolic health they represent meaningful options.
“This review highlights fructose as a central player in metabolic health,” Johnson said. “Understanding its unique biological effects is critical for developing more effective strategies to prevent and treat metabolic disease.”
The conventional nutritional framework has treated all sugars as approximately equivalent, calories in, calories out.
This paper argues that framework is wrong in a specific and important way. Fructose is not just a calorie. It is a signal. And in a food environment saturated with that signal, the body responds accordingly.
