understanding fructose

Question
I have take nutrition in college but don't remember learning anything about this.

I just read this, "Fructose, on the other hand, does not trigger insulin release. This in turn means that fructose doesn′t affect leptin levels either. Since it increases neither insulin nor leptin levels, fructose consumption does not generate the same satiety signals as glucose. The result is overeating and weight gain."

Could you tell me more about fructose. Does it just go straight to the liver to be converted to glucose and that is why is only refills liver glycogen stores, then when liver glycogen is full it turns to adipose tissue?

Once it is turned to glucose why doesn't it enter the general circulation to possibly refill muscle glycogen?

Also, if it doesn't cause insulin secretion that why is it listed on the GI index? I'm confused how it doesn't cause insulin secretion yet it raises blood sugar. How can the two be mutually exclusive.

Also, I was reading about treatment of hypoglycemia and most mentioned fructose sources 4-6 oz OJ, 4-6oz pop, etc.. but I was confused when I saw milk listed. Wouldn't the protein in the milk cause a slower rise in blood sugar?

Sorry for all the questions but I'm really trying to understand all of this.

Thanks so much!

Tom

Answer
Tom, I'm not sure I can answer your question but I do know that the body metabolizes fructose faster and therefore is stored as fat faster than other carbohydrates.  The body turns all carbs into glucose, which in turn should increase insulin (the insulin gets the glucose into the cells).  Milk works pretty quickly at raising blood sugar - protein doesn't negate a rise in blood sugar.  Good question though.  My recommendation would be to eat fruit (limit if you have diabetes) but to not drink juice and definitely avoid high fructose corn syrup - a processed sweetener that provides absolutely no nutritional benefit.  Take care,

Jen Birge, RD
www.realhelpforweightloss.com

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