The Role of Fructose

December 30, 2018

Many people think that sugar is sugar, but there are different types and sugar comes in many forms. Compared with glucose, fructose plays a primary role in development of metainflammation, obesity, prediabetes, and type 2 diabetes

Fructose directly increases de novo lipogenesis, promotes dyslipidemia, decreases insulin sensitivity, increases visceral adiposity, and stimulates the reward center, similar to cocaine.

What is sugar?

Because glucose is the sugar that we most often talk about and measure in diabetics, most people assume that their regular table sugar is made of glucose. However, common table sugar is actually a disaccharide, made of two monosaccharides, fructose and glucose, bonded together in a 1:1 ratio.

High fructose corn syrup (HFCS) contains about 5% more fructose than glucose. HFCS is manufactured by hydrolyzing corn starch into glucose, which then is isomerized into fructose. Fructose is preferred by food and soft drink manufacturers because fructose exerts a significantly increased perception of sweetness and likely because its production is subsidized.  Glucose has a sweetness index of 74 compared to sucrose of 100 or fructose of 173.

According to the CDC, over 30 million Americans have diabetes, with 1 in every 4 not knowing their diagnosis. Fructose is more strongly linked to obesity and diabetes than glucose. There is no biochemical reaction in any eukaryotic organism that requires fructose.

Metabolism of glucose and fructose

Glucose can be utilized as an energy source by almost every cell in the body. Only the liver can metabolize fructose, and it will preferentially convert fructose into fat storage.  The body has the ability to handle a small amount of fructose at a time, without adverse health consequences. Fructose does come naturally from fruits, but the absorption is slow due to the large amount of fiber.  Unfortunately, removing the fiber by juicing or destroying the fiber, as done in a smoothie, dramatically increases the speed of absorption, overwhelming the liver and sending a fructose rush to the brain.

Glucose consumption normally causes insulin release from the pancreas. Insulin acts on surface cell receptors, which allow glucose absorption into the cell for energy use or converting it to fat inside the cell.  High levels of insulin, in the presence of high levels of glucose, cause a liver enzyme [phosphofructokinase PFK] to convert glucose to fructose, which is then quickly turned into fat storage and not used for energy production.  However, if you directly ingest fructose, it bypasses the enzyme gateway and insulin is not released, and it goes straight to fat storage.

The metabolism of fructose differs from that of glucose, with liver metabolism of fructose favoring de novo lipogenesis [fat production directly from fructose].  Additionally, fructose does not stimulate insulin secretion or leptin production. Insulin normally regulates the absorption of sugar into the cells, and leptin normally notifies brain receptors that you are full.  Because insulin and leptin act as key signals in the regulation of food intake and body weight, fructose consumption causes yet further hunger and additional weight gain.  The body is rapidly storing fat, and doesn’t know it’s full.

Insulin resistance from fructose and the beginning of metabolic inflammation

Fructose can also directly trigger insulin resistance. When mice are fed with excessive amounts of fructose, they produce carbohydrate responsive element-binding protein, or ChREBP, which blocks the liver from responding to the insulin.

Fructose is 20 times more likely to cause fatty liver (the key problem of insulin resistance) compared to glucose alone.  Fructose feeding studies, replacing glucose with a calorically equal amount of fructose, document  a 5x increase in de novo lipogenesis and an increased liver fat by 38% within eight days.

[The metabolism of ethanol (alcohol) is similar to that of fructose. Nearly 80% of the ingested ethanol is delivered to the liver, and metabolized to acetaldehyde, which also stimulates de novo lipogenesis.]

Fructose overfeeding can provoke insulin resistance. Healthy subjects overfed 1000 calories per day of fructose demonstrated a 25 percent worsening of their insulin sensitivity in seven days.

Fructose induces insulin resistance even at typical consumption doses, in less than eight weeks. Subjects were fed 25 percent of their daily calories as Kool-Aid sweetened with either glucose or fructose. The fructose group increased their insulin resistance, and could be clinically classified as pre-diabetic.  The glucose group did not.

Fructose engages in the Maillard reaction, or glycation seven times faster than glucose, and  a metabolite of fructose does it 250 times faster.  We commonly measure this as HgBA1C for glucose.  The measure for fructose is fructosamine.  This glycation effect makes the cell walls sticky, and the receptors not work.  This may explain why patients with high glycation levels require more pain medication, because their receptors simply don’t work.  It also is part of the explanation how insulin resistance occurs.

Fructose and addiction

Fructose stimulates the reward center of the brain while glucose does not.  Data suggests that the fructose molecule in sugar is what it makes it addictive.


  • Glucose activates the cortex, the basal ganglia, and certain other parts, but not the limbic system.  Glucose results in a sensation of serotonin-induced happiness. By contrast, fructose stimulates the limbic system and is associated with increased dopamine release in the nucleus acumbens, similar to other addictive drugs (glucose does not stimulate the nucleus acumbens).  Fructose results in a sensation of dopamine-induced pleasure.

Agricultural subsidies

Governmental subsidies were initially a method to subsidize farmers during the Depression and the Dust Bowl in 1933.  We had a destitute population in the American southwest, dying of famine. Most of the the food and food manufacturers were in the Northeast.  By the time it took to transport food by rail to the Southwest, it would go rancid. They had to process it: remove the fiber from the  wheat, package it in 5 pound bags, ship it to the Southwest, and then bake it locally. The subsidy was designed to make it worthwhile for the American food industry to invest in a processing and distribution system for a famine-stricken population, which made sense through World War 2.

Unfortunately, President Nixon, concerned about re-election, knew that fluctuating food prices caused political unrest.  Nixon instituted a policy of maintaining low consumer prices for food by agricultural subsidy.  Until that point, our subsidies were actually designed to pay farmers to not grow certain crops and maintain inflated prices. This policy also allowed the soil to regain nutrient after crop harvest.  His agriculture secretary, Rusty Butz, changed farming operations so soil was no longer left fallow; there was no time to restore nutrient after a crop was harvested.  It also encouraged monocropping and megafarms.  Subsidies have created an agricultural farmer dependency on governmental support.  The massive overproduction of just a few grain items resulted in a huge surplus and difficulty in long-term storage.  Distributing this slowly rotting surplus was solved through the food stamp system, creating a consumer dependency on governmental support. Unfortunately, these processed staple items are carbohydrate-rich, but have had most of their fiber stripped and fat removed to prevent rancidity,  and lack much of the soil-derived micronutrients.

Governmental subsidies and import tariffs have resulted in corn being a much more economical sweetener than sugar–a trend that is not seen in other parts of the world.  The consumption of HFCS increased by more than 1000% between 1970 and 1990, far exceeding the changes in intake of any other food or food group. HFCS now represents more than 40% of caloric sweeteners added to foods and beverages, a daily average of 132 calories per person. The effect of governmental subsidy is most evident when you compare the same soft drink in the United States to one in Mexico; for example, Coke contains corn syrup as the sweetener in the United States while it contains cane sugar in Mexico.

The per capita consumption of high fructose corn syrup — the primary sweetener in soft drinks and other sweetened beverages — has increased from 38.2 pounds in 1980 to 868 pounds in 1998 (Chou et al., 2004). In 1942, annual U.S. production of soft drinks was 90 8 oz. servings per person; in 2000, it was 600 servings (Jacobson, 2005).

Other names for sugars:

Processed foods will most likely have sugars added. Unfortunately, they can go by any number of names. While this is an extensive list, it is not complete. The more naturally you can eat your foods, the better success you will have with creating a permanent weight loss solution.

Agave Syrup


Any name ending in “ose” or “ol” or “syrup”

Barbados Sugar

Barley Malt

Blackstrap Molasses

Black Sugar

Brown Sugar

Cane Juice or Cane Juice Crystals

Cane Sugar

Caramel or Caramel Coloring

Castor Sugar

Confectioner’s Sugar

Corn Sweetener

Corn Syrup – a manufactured syrup of corn

starch, containing varying proportions of glucose

maltose, and dextrose

Corn Syrup Solids

Crystallized Cane Juice


Date Sugar


Demerara Sugar

Dehydrated Cane Juice or Dehydrated Cane

Juice Crystals





Dextrose (glucose) – a simple sugar made of

only one molecule


Evaporated Cane Juice

Evaporated Cane Juice Sugar

Florida crystals (a trademarked name)

White or Brown Sugars

Fructose – a simple sugar refined from fruit

Fruit Juice Concentrate

Galactose or Galatactose

Glucose or Glucose Syrup

Golden Syrup

Grape Sugar

Grape Juice or Grape Sweetener

High Fructose Corn Syrup (HFCS)


Hydrolysed or Hydrolyzed Starch

Hydrogenated Glucose Syrup

Hydrogenated Starch Hydrolysates (HSH)

Invert Sugar



Lactitol or Lactital

Lactose – a simple sugar from milk


Malt Extract

Malt Syrup




Maple Syrup




Organic Dehydrated Cane Juice

Organic Brown Sugar



Powdered Sugar

Raw Cane Crystals

Raw Honey

Raw Sugar