Here
comes the first bite. That maple syrup taste is so sweet! It sends
a signal to the command center of this operation (the brain) that
something really good is coming down the old hatch. Time to rev
up the system for digesting something sweet. Even before the first
bite of pancake hits the stomach, the message goes to the brain:
send out the insulin!
Once
the pancakes and maple syrup arrive in the stomach, other hormones
called GIP and GLP-1 are put out by the body. These hormones increase
the release of insulin, affect the rate at which the stomach empties,
influence appetite and feeding behavior, and affect the function
and size of beta cells (the cells that secrete insulin) in the pancreas.
. Insulin is our very best friend as fat cells, because it is the
key to filling us up with more and more fat. And we love getting
fatter and fatter!
Okay,
all that sugar has been absorbed by the blood stream now and it’s
heading toward the liver. There are sensors in the vein leading
to the liver that sends more instructions: Start storing that sugar
in the liver and other tissues! Stop, repeat, stop, eating! Insulin,
let’s go!
In
the liver cells, called hepatocytes, biochemical reactions get started
that will convert the sugar into glycogen, which can be used for
short-term energy needs. The liver has only a limited capacity for
glycogen storage, so once it is filled up, the rest of the sugar
is converted into fat. That makes today my lucky day. This breakfast
will exceed the glycogen-storage capacity of the liver by several
hundred calories of sugar, so we fat cells are going to get pumped
up!
Some
of the glucose is chemically changed into xylulose-5-phosphate (
a slightly different sugar with a phosphate molecule attached).
That guy is really our friend, because it moves into the nucleus
of the cell and turns on genes that will ultimately make fatty acids.
Fatty acids are the molecules that move into us fat cells and plump
us up.
The
sugar also turns on cholesterol synthesis, so those blood vessels
better watch out or they’ll be clogged before you know it.
Best of all (from my humble point of view) the sugar in the blood
stream tells the pancreatic beta cells to put out insulin. That
insulin is great stuff. Fill me up, baby!
But . . . now it is 10;30 AM and the body is hungry again? What's up with that?
It's a funny thing. Breakfast this morning, pancakes, maple syrup, bacon and orange juice was delicious. It clocked in at about 800 calories, and generated a sensation of complete satiety by 8:00 AM. Yet the command center (brain) was signaling “hungry, I'm hungry” at about 10:30 AM. What happened? Well, the pancakes were quickly converted to simple sugars and the maple syrup was absorbed as sugar. The orange juice, with no pulp, had no fiber to slow down its absorption, so it wound up in the blood stream as sugar, too. The end result was a massive outpouring of insulin, which drove down the blood sugar level very rapidly. Hence, the sensation of hunger at 10:30 AM.
Good thing the coffee cart came around just about that time at work. One large cup of coffee, two sugars, no milk, and a chocolate-covered donut really hit the spot. This is really a bonanza day for us fat cells, because the cycle started all over again – the sugar from the coffee and the donut was rapidly absorbed. The glycogen stores in the liver and muscle were all full from the morning meal, so the body's biochemical mechanisms immediately went to work converting all this sugar into fatty acids and triglycerides. These molecules are then moved directly in the fat cells. This is really great for us here in Adipo-City!
Well, it's 12:30 PM now and we're starving again. The command center has decided to go out for a quick lunch at a fast-food restaurant. This is going to be good. A double cheeseburger with fries and a 32 oz diet soda should be just the ticket. The command center always chooses diet soda because there's no point in adding extra calories, right? On the way back to the office, the diet soda is the first to come down the pike. Just like this morning's maple syrup, the sweet taste in the mouth sends a signal to the command center that a sweet morsel is coming and will need to be dealt with. So the pancreas gears up for digestion of the incoming sweet, and insulin is secreted. But guess what? That diet soda has no sugar in it, and so the insulin acts on the existing sugar in the blood stream, which is already low in the aftermath of the mid-morning coffee and donut snack. By the time we get back to the office and dig in to the burger and fries, the hunger signals are off the chart, and the food vanishes in a New York minute.
Those fries are the greatest. The fast food restaurants spike them with sugar so they taste fabulous and keep us coming back for more. The potatoes themselves are rapidly digested into sugars. And of course, the fats from the fries don't even have to be converted into fat; they're already there. Come on down!
Now, the cheeseburger, that's another story. We've got the bun, which is made of enriched white bread, and is digested to sugars just as fast as the fries. The cheeseburger itself is made up of protein and fat. The protein is broken down into amino acids, which can be used to rebuild muscle and other bodily structures. But there is a limit to how many amino acids can be put to use at any given time, so if the body takes in too much protein, guess where it winds up? In the fat cells, of course. Those excess amino acids get converted to either sugars or fats, and if the glycogen stores are full, the sugars eventually wind up as fat. Biochemistry is a wonderful thing for us fat cells.
