The knocks on fructose:

- Fructose causes the metabolic syndrome: insulin resistance, high blood pressure, high blood glucose, high triglycerides and LDL cholesterol, visceral fat. Researchers actually feed a high-fructose diet to rats as a quick way of giving them metabolic syndrome, so they can study it!

- Fructose doesn't stimulate insulin secretion. The pancreatic beta-cells that secrete insulin don't have a receptor for fructose, so they don't "see" it. It's good to have insulin released after meals, since this causes the satiety hormone leptin to be released. So fructose bypasses the leptin aspect of the body's satiety signals.

- Fructose causes leptin resistance in rats, so they gained more when they were given a high-fat diet. Leptin resistance is associated with being overweight. It may be part of why people get fat, why their bodies don't tell them to stop eating.

- Fructose and glucose interact differently with a satiety signaling system in the brain involving malonyl CoA in mice. Glucose causes satiety via this system but fructose doesn't.

- Fructose causes glycation of proteins, which is part of the mechanism of aging. Glucose is less reactive than fructose and causes far less glycation of proteins. Fructose feeding in rats caused changes typical of aging in their skin collagen. Fructose promotes atherosclerosis via glycated proteins as well as via high triglycerides and LDL cholesterol.

- Fructose makes pancreatic cancer cells proliferate. But high fructose intake reduces the risk of prostate cancer.