Fructose is even more strongly linked to obesity and diabetes than glucose. From a nutritional standpoint, neither fructose nor glucose contains essential nutrients. As a sweetener, both are similar. Yet fructose is particularly malevolent to human health compared to glucose due to its unique metabolism within the body. Glucose and fructose metabolism differ in many significant ways. Whereas almost every cell in the body can use glucose for energy, no cell has the ability to use fructose. Once inside the body, only the liver can metabolize fructose. Where glucose can be dispersed throughout the body for use as energy, fructose is targeted like a guided missile to the liver. When large quantities of glucose are eaten, it circulates to virtually every cell in the body, helping disperse this load. Body tissue other than the liver metabolizes eighty percent of ingested glucose. Every cell in the body, including the heart, lungs, muscles, brain, and kidneys help themselves to this all-you-can-eat glucose buffet.

This only leaves the remaining twenty percent of the incoming glucose load for the liver to mop up. Much of this glucose is converted into glycogen for storage leaving a little glucose as substrate for new fat production. The same does not hold true for fructose. Large quantities of ingested fructose goes straight to the liver, since no other cells can help utilize or metabolize it, putting significant pressure on the liver. Levels of carbohydrates and insulin may be 10 times higher here than in other parts of the circulation. Thus the liver is exposed to far higher levels of carbohydrates - both fructose and GlycoModeBloodSugar.com glucose than any other organ. It is the difference between pressing down with a hammer and pressing down with a needle: all the pressure is directed onto a single point. Sucrose provides equal amounts of glucose and fructose. Where the glucose is metabolized by all 170 pounds of an average person’s tissue, an equal amount of fructose needs to be valiantly metabolized by only 5 pounds of liver.

What this means practically is that fructose is likely 20 times more likely to cause fatty liver (the key problem of insulin resistance) compared to glucose alone. This explains how many primitive societies could tolerate extremely high carbohydrate diets without developing hyperinsulinemia or insulin resistance. The liver metabolizes fructose into glucose, lactose and glycogen. There are no limitations on this system of metabolism for fructose. The more you eat, medicalsysconsult.com the more you metabolize. When the limited glycogen stores are full, the excess fructose is changed directly into liver fat through de novo lipogenesis. Fructose overfeeding can increase DNL five fold, and replacing glucose with a calorically equal amount of fructose increases liver fat by a massive 38% within only eight days. It is precisely this fatty liver is crucial to the development of insulin resistance. Fructose’s propensity to cause fatty liver is unique among carbohydrates. The fatty liver directly causes insulin resistance setting in motion the vicious cycle of hyperinsulinemia - insulin resistance.

Furthermore, this harmful effect of fructose does not require high blood glucose or blood insulin levels to wreak havoc. Further, this fattening effect, because it acts through fatty liver and insulin resistance, cannot be seen in the short term - only in the long term. The metabolism of ethanol (alcohol) is quite similar to that of fructose. Once ingested, tissues can only metabolize 20% of the alcohol leaving 80% delivered straight to the liver, where it is metabolized to acetaldehyde, which stimulates de novo lipogenesis. The bottom line is that alcohol is easily turned into liver fat. Excessive ethanol consumption is a well-known cause of fatty liver. Since the fatty liver is a critical step toward insulin resistance, it is no surprise that excessive ethanol use is also a risk factor for the development of metabolic syndrome. That fructose overfeeding could provoke insulin resistance has been known as far back as 1980. Healthy subjects overfed 1000 calories per day of fructose showed a 25 percent worsening of their insulin sensitivity - after just seven days!

Those given an extra 1000 calories per day of glucose did not manifest any similar deterioration. A more recent 2009 study reinforced how easily fructose induces insulin resistance in healthy volunteers. Subjects were fed 25 percent of their daily calories as Kool-Aid sweetened with either glucose or fructose. While this seems high, many people consume this high proportion of sugar in their diets. The fructose, but not the glucose group, had increased their insulin resistance so much that they would be clinically classified as pre-diabetes. Even more remarkable, this development only needed eight weeks of fructose overconsumption. It only takes six days of excess fructose to cause insulin resistance. It only takes eight weeks to allow pre-diabetes to establish a beachhead. What happens after decades of high fructose consumption? The result is a diabetes disaster; precisely we are having right now. Fructose overconsumption stimulates fatty liver and leads directly to insulin resistance. There is definitely something sinister about overconsumption of fructose.