Fructose and Glucose: A HealthCentral Explainer

SSuchy Editor
  • (Flickr, ShellyS)


    A study published in the Journal of the American Medical Association (JAMA) – just in time for New Year’s resolutions – suggested that the sugar fructose may actual lead to more weight gain than its sister monosaccharide glucose.  Which prompted us to as ask: What exactly is the different between fructose and glucose? And, more importantly, what do those differences have to do with your waistline?


    Simple sugars: the basics


    Fructose and glucose are two of three simple monosaccharaides, meaning the most basic unit of carbohydrate with any biological importance.  Molecularly speaking, there is not much to these compounds.

    Add This Infographic to Your Website or Blog With This Code:


    Fructose is the natural sweetener in many of your favorite fruits.  In its dry, powder form, fructose is odorless and the most water soluble of all the sugars.


    Glucose, of the other hand, is another monosaccharide found mostly in the starches of carbohydrates.  Believe it or not, your pasta and rice actually contain sugar, and this sugar is mostly glucose.


    The JAMA study


    The study published in JAMA found that the sugar fructose – of high fructose corn syrup fame – affects the brain in a different way from the less-sweet glucose.  


    How specifically?  The study on 20 average-sized adults found that the sugar glucose, when consumed, slowed blood flow to the areas of the brain that control appetite, motivation and reward processing.  In other words: the more glucose the person consumed, the less hungry he or she felt.


    The sugar fructose, however, did not prompt the same slow in blood flow.  This means that no matter how much fructose the person consumed, they did not feel any fuller. 


    Are you full yet?


    There are several conclusions one could draw from this, but one of them is that eating foods high in fructose could prompt you to eat more than you need because you simply do not feel full after eating these foods. 


    Ever notice how you can absentmindedly eat a whole bag of candy without feeling full right away?  Part of the reason this happens is because of what the researchers observed in this study: It takes a lot longer to feel full from eating foods high in fructose, such as  candy or other processed foods than it does from eating high protein foods, such as beans or meat.


    Adding to fructose’s rap sheet: A 2009 study published in the Journal of Clinical Investigation found that weight gain fueled by an excess of fructose was more likely to trigger unhealthy changes in liver function and fat deposits.


    What to do now?


    But is it enough to simply say, “Avoid fructose?”  Unfortunately, no.  First, because there are some foods with natural fructose, such as fruits, that are very good for you.  With these foods it is best to simply stick to the tried and true mantra: “Everything in moderation.”


    In the case of added sugar, however, very few foods with an extra sweet kick contain either all fructose or all glucose.   In fact, most foods that contain sugar have some combination of the two monosaccharaides.  Table sugar, for example, is called sucrose and has a 50-50 combination of fructose and glucose.


    Add This Infographic to Your Website or Blog With This Code:

    Pure glucose is generally not used to sweeten anything on its own because it tastes significantly less sweet than fructose.  The American sweet tooth would spot the difference right away.


    The best thing to do is to attempt to cut down on or totally avoid added sugars as much as you can.




    Journal of the American Medical Association, Effects of Fructose vs Glucose on Regional Cerebral Blood Flow in Brain Regions Involved With Appetite and Reward Pathways. (January, 2013). Retrieved from:


    The Atlantic, Study: Another Bad Thing About Fructose. (January 2013). Retrieved from:


    Time Health & Family, All Sugars Aren’t the Same: Glucose is Better, Study Says. (April, 2009). Retrieved from:,8599,1892841,00.html

Published On: January 16, 2013