High fructose processed foods linked to obesity, gout, hypertension, diabetes, cholesterol and fatty liver
There has been a "cloud" over the health benefits of fructose added to processed foods over the last few decades. Food manufacturers have been adding pure fructose to foods in the quest to lower the glycaemic index (GI) of the food because fructose does not affect insulin production therefore is considered to be a low GI sugar (this is contrast to glucose which does raise insulin levels). The food industry have also been adding fructose in the form of corn syrup (popular in the United States) or sucrose (this is half fructose) to foods, especially low fat/diet foods to improve flavour. There is emerging evidence that this may be making the obesity epidemic even worse, starting with damage to our liver cells, the hepatocytes.
The only organ in your body that can take up fructose is your liver and this is where the problem begins. In contrast, glucose can be taken up by every organ in the body, only 20% of glucose load ends up at your liver - the rest is metabolised by muscles, brain, kidneys, heart etc. .
Fructose increases uric acid which in turn increases blood pressure and causes gout (where uric acid crystals are deposited in joints)
Fructose increases phosphate depletion of the hepatocyte which ultimately causes an increase in uric acid. Uric acid is an inhibitor of nitric oxide - nitric oxide is your naturally occurring blood pressure lowerer.
Fructose increases fat production in the liver (also known as denovo lipogenesis) which in turn increases blood fats like cholesterol and triglycerides (glucose does not do this) and liver fat (which could result in non-alcoholic fatty liver disease). In fact fructose is being metabolised via the same pathway as alcohol and is actually damaging your liver in the the same way as alcohol. Fructose causes deposition of fat within the liver so it is actually like alcohol and alcohol is like a fat. So in contrast to glucose, it can be said that fructose behaves like a fat.
Fructose increases inflammation which in turn increases insuln levels in the long term: fructose initiates an enzyme called Junk one in the liver which stimulates the inflammation pathway. This in turn stops the insulin receptor in your liver from working resulting in higher insulin levels in the body (pancreas responds to this situation by pumping out more insulin in the hope to get the insulin working) . Eventually insulin resistance sets in where your insulin receptors are no longer responding to the excessive amounts of insulin and thus less glucose gets into the cells and more remains in the blood (this is when diabetes is diagnosed). High insulin levels stimulate the conversion of sugar to fat which means you will be storing more fat in the liver (which could result in non-alcoholic fatty liver disease) and more fat in fat cells, especially around the abdomen and internal organs (resulting in abdominal/visceral obesity).
Fructose doesn't raise your insulin in the short term because there's no fructose receptor on your beta cell in your pancreas which produces insulin but there is a receptor for glucose (fat also does not increase insulin production). However, in the long term fructose will raise insulin due to the effects on inflammation in the liver which in turn can make you insulin resistant (mentioned above).
Bottom line: A low fat diet containing fructose (as sugar or pure fructose) is really a high fat diet because fructose behaves like a fat. We were not designed to eat a lot of refined sugars, we're supposed to be eating our carbohydrate, particularly our fructose, with high fibre in unprocessed foods like fruit and vegetables. If you are trying to lose weight, lower your blood pressure, blood fats or fatty liver reduce your intake of sugars/fructose in processed foods that do not contain fibre (like soft drinks, fruit juices, sweet yoghurts, cakes, biscuits, fructose sweetened protein drinks etc) even if the label says low GI.

Source: ABC Health Report - Dr Norman Swan interviews Obesity expert Dr Robert Lustig Professor of Pediatric Endocrinology, University of California http://www.abc.net.au/rn/healthreport/stories/2007/1969924.htm

Last Updated: July 2008