Fructose

       Here is an interesting article I just read on FitBie this morning. Basically, it is talking about foods that you may think are healthy, except they can make you fat or keep you in that plateau.  I would say that after reading it, some things made sense.
In the article he mentions pasta and granola, stating that the carbs become sugar, which in turn signal insulin and that signals fat storage. You'd me surprised at the some of the foods like black beans and sweet potato, which hes says just have too many carbs. I haven't looked at any research that has shown this to be true or not, but one thing he brought up was the pear, stating it had about 90 calories of sugar. And this is where I started thinking, because I hate when fruit is compared to candy. The sugar in a pear is different. Here's why. A pear contains mostly fructose. According to this website fructose in a pear ( I did the math myself 4 kcals per gram of sugar) there are only about 22 calories of insulin stimulating sugar in a pear. That sugar is glucose. There is about 45 calories from fructose in a small pear. Fructose does not stimulate insulin release.
Now, I'm not saying a lot of fructose is good for you. Far from it. I'm saying his point was that a pear has 90 calories of sugar that will stimulate insulin ( a medium-sized pear is only about 60-70 calories, so I don't know why he says 90, but anyway)and really only 22 of those calories stimulate insulin. I don't think this is what is behind the obesity epidemic. 

I've already said that too much glucose sucks because it causes a huge spike in blood sugar and a huge release in insulin that leads to getting fat among other nasty side effects.
If you want to know a little about fructose here you go. Fructose has a completely different metabolic pathway. wikipedia fructose metabolism (I'm using wikipedia, because it is an easier than scanning my human nutrition text book:) Now with fructose, it doesn't raise insulin because, as previously stated the metabolism is different.
Here's a nice picture showing the difference between glucose and fructose.

If you haven't had biochemistry, there is no reason to start. This is just showing where the difference in metabolism is. It doesn't need insulin to get into the cell. The Fructose forms glyceraldehyde and then an enzyme converts it to glyceraldehyde-3- phosphate and it can enter the gluconeogenic pathway (to make glucose or glycogen) or it can enter the lower glycolytic pathway  (the same pathway as glucose; it just skips the first part) and becomes pyruvate, which gives us ATP=Energy and can also become triaclyglycerols which is stored as fat. 

They both give us energy. What's bad about that? Nothing, we need energy. We just don't want more than we can use or else it becomes fat. I just don't by that that 22 calories of insulin stimulating glucose or the 45 calories of non insulin stimulating fructose from a pear is what makes us fat....

But in large quantities (here's some complicated papers that talk about this - paper 1, paper 2) they are no good. Insulin is important. If we don't make it we will die. That is why type 1 diabetics have to inject insulin into their bodies so they won't go into shock and die. It also signals leptin. Leptin signals the down-regulation of ghrelin. (Ghrelin says "I'm hungry", Leptin says" you ate; you're full). Fructose will not signal this and studies show that you will not feel full from that sugar and will overeat. It also shows that fructose will first make glycogen (our stored glucose in our bodies) and then it will make the triacylglycerols, which become stored fat on our liver (and fat elsewhere on our bodies) , and contribute to non-alcoholic fatty liver disease.

So if you have too much glucose you trigger the release of a lot of insulin which triggers fat storage and if you have too much fructose you can eat without feeling that you have eaten, over eat and store more fat. 

But if you are just having a pear at breakfast (not Cinnamon Toast Crunch or Pepsi) you will feel full from the water and fiber content of the pear, there is still some glucose to signal insulin (and the whole leptin-ghrelin fullness thing) and those 45 calories of fructose are probably not going to have a devastating effect on your liver. If you're active in your day you will use those calories up. If you have a donut and sit around all day, you won't.

 Sugar in large quantities such as in a Pepsi isn't good for you. Pepsi has 42 grams of sugar. This is from Pepsi's own website that honestly I don't think I can stomach reading in its entirety.

What is the difference between sugar and HFCS?

Sugar comes from either sugar cane or sugar beets while high fructose corn syrups come from corn. Table sugar and the HFCS used in soft drinks have the same calories and sweetness and research shows that our bodies cannot differentiate one from the other. Both table sugar and HFCS are made up of the two simple sugars, fructose and glucose. The difference between the two sweeteners is in the amount of these two simple sugars they contain. Specifically, table sugar is made of 50% fructose and 50% glucose while the most common type of HFCS is made of 55% fructose and 45% glucose.

  

So, according to Pepsi, if you are drinking the recipe with HFCS, in 12 oz you are getting 99 calories from fructose and 81 calories from glucose ( a way different amount than a pear minus the fiber and the nutrients).

Now please do not confuse HFCS (high fructose corn syrup) with fructose. HFCS is a mixture of fructose and glucose in the amounts specified above. They are only saying that when it comes to eating HFCS or sugar they are both bad for you. Now, they are not using those words but sugar in that form of empty calories whether its a little more fructose or glucose doesn't matter because they both suck. They may just suck in a slightly different way. And I would call HFCS sugar. Drinking soda because it is made with sugar and not HFCS is ridiculous. You shouldn't be drinking 42 grams of sugar in a 12 oz drink that contains no nutritional value whatsoever. The 17 grams in the pear is not the problem....

There is research in regards to plateaus and being carbohydrate sensitive, where fat fasting to get into ketosis  (fat-burning metabolism) is used. That is another subject for another time. I think that instead of demonizing fruit(incorrectly demonizing it, he could've demonized it better saying the 45 calories of fructose was too much) first cut out the sugary cereals, the handfuls of chocolate chips (my problem) and the sub sandwiches on a 400 calorie baguette and then see if you need to explore fat fasting and cutting down on fruits.