I am going to a school that wants me to eat nothing but fruit on the days that we attend class (once a week). The idea is that we follow a routine, that we renounce a little something and as a community do this one thing together all day long. So….I ate three oranges for breakfast, and I am already suffering from hunger pangs at 8AM, when I normally only have them at around 1130 after my bacon and egg breakfast. Fructose sucks.
I know why we have hunger pangs so soon after we eat sweets. Fructose is a form of sugar. The sugar in your sugar canister is half fructose and half glucose. When combined with glucose in the normal proportions this kind of sugar is called sucrose. From Livestrong.com:
One medium-sized navel orange contains 17.56 grams of total carbohydrates, which includes 11.9 grams of natural sugar. Sucrose accounts for half of the total sugar. Another 23 percent of the total comes from glucose, while fructose represents 27 percent of the sugar in an orange. One navel orange has 69 calories. Almost 48 of the total calories come from sugar because each gram of sugar provides 4 calories, according to Iowa State University. – See more at: http://www.livestrong.com/article/267094-natural-sugars-in-oranges/#sthash.lEmbOP3m.dpuf
So the sucrose disaccharide that they say is in the orange is half glucose, and half fructose. The sucrose is broken immediately into its component parts inside of you. The fructose you get eating an orange is 77% of the total monosaccharides contained in it.
Glucose by itself is ‘starch’. Think white rice. When you eat glucose (mashed potatoes) this is what happens:
1. Glucose metabolism is insulin-dependent. Consuming glucose raises the glucose level in the bloodstream, stimulating insulin release, which promotes energy storage into fat cells and causes weight gain.
2. The overwhelming majority of glucose in the liver will be directed toward forming glycogen, or liver starch, which is not harmful to the liver cell. This also will keep the liver from releasing glucose into the blood, preventing diabetes.
3. A small amount of glucose will be metabolized by the liver mitochondria for energy.
4. Any excess glucose in the liver that is not shunted to glycogen and not metabolized by the mitochondria for energy will instead be converted to triglycerides. High triglyceride levels in the blood can promote development of cardiovascular disease.
Lustig, Robert H. (2012-12-27). Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease (pp. 120-121). Penguin Publishing Group. Kindle Edition.
The fructose dose you get eating that orange undergoes a completely different process, and in combination with the glucose you are eating causes different biological effects:
Let’s now consume 120 calories of sucrose (60 of glucose, 60 of fructose)— for example, an 8-ounce glass of orange juice…The 60 calories of glucose do the same 20-80 split, so 12 calories of glucose will enter the liver. But, unlike with glucose, which can be metabolized by all organs, the liver is the primary site of fructose metabolism… Give or take, the whole 60 calories of fructose end up in the liver. So, the liver gets a 72-calorie dose, triple the amount as with glucose alone.
1. Triple the dose means the liver needs triple the energy to metabolize this combo versus glucose alone, depleting the liver cell of adenosine triphosphate (or ATP, the vital chemical that conveys energy within cells). ATP depletion leads to the generation of the waste product uric acid. Uric acid causes gout and increases blood pressure.
2. The fructose does not go to glycogen. It goes straight to the mitochondria. Excess acetyl-CoA is formed, exceeding the mitochondria’s ability to metabolize it.
3. The excess acetyl-CoA leaves the mitochondria and gets metabolized into fat, 9 which can promote heart disease.
4. Fructose activates a liver enzyme, which is the bridge between liver metabolism and inflammation. This inactivates a key messenger of insulin action, leading to liver insulin resistance.
5. The lack of insulin effect in the liver means that there is no method to keep the glucose down, so the blood glucose rises, which can eventually lead to diabetes.
6. The liver insulin resistance means the pancreas has to release extra insulin, which can force extra energy into fat cells, leading to obesity. The fat cells that fill up most are in the visceral fat, the bad kind associated with metabolic disease.
7. The high insulin can also drive the growth of many cancers.
8. The high insulin blocks leptin signaling, giving the hypothalamus the false sense of “starvation,” and causing you to eat more…
Lustig, Robert H. (2012-12-27). Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease (pp. 123-124). Penguin Publishing Group. Kindle Edition.
The hunger I feel already is a function of having eaten fructose. I am not really in need of energy, but my biology is turned on to make me think I am. This fact would make it very difficult for me to turn down a sweet treat. If a vendor would show up now with a box of donuts or Christmas cookies it would take incredible willpower to deny them, the way that I feel right now. Had I eaten my bacon and egg breakfast I wouldn’t be having any problem thinking that I am starving. No fructose in bacon and eggs.
The real problem with the store-bought diet is all of the sugar that is in it these days. They hide it, they call it by different names. It is in eight out of ten processed foods. You wouldn’t play Russian roulette with those kinds of odds, but just about every boxed, bagged or bottled food is going to contain fructose.
I don’t know if I will be able to keep playing with the other kids in my class if they insist that I eat nothing but fruits for one day out of the week. When I eat fructose I want it to be dessert when I am out on a date with my sweetie, not as a symbol of devotion. If they could make the symbol something like ‘eat only single ingredient foods’ then I could advocate for that strongly. The science is behind doing that for the good of your body.