Insulin--Your Friend and Your Enemy, Part II

In Part I we saw that insulin is a food storage hormone, somewhat like the grocery stocker who puts shipments of food onto the correct shelves in the grocery store. We can't survive without insulin, but sometimes insulin hurts us as well as helps us.

As people get older, they can develop a condition called insulin resistance. In early insulin resistance, insulin is still secreted by the pancreas, but gradually the insulin does a poorer and poorer job as a food stocker. This happens at different rates in different tissues.

Remember gluconeogenesis--the process our liver uses to make extra glucose out of the food we eat? Normally when insulin is released, the liver responds by shutting off its production of extra glucose. That makes sense. If we're getting glucose in our food, there is no reason for the liver to make more of it. But when insulin stops doing its job properly, the liver doesn't get a clear message to stop making glucose, and blood glucose levels rise higher than they should. Think of bags of sugar starting to litter the aisles in the grocery store.

Elsewhere in the body, our muscles normally respond to insulin by taking up glucose from the blood and storing it as muscle glycogen. But if insulin starts doing a poor job of stocking muscle cells with glucose, the glucose stays in the blood and muscle cell "shelves" start to become empty. In this case, not only are the bags of sugar littering the aisles, but they are missing from the shelves where they are supposed to be.

So insulin resistance produces a condition in which there is excess glucose in the blood from gluconeogenesis and also from the fact that muscle cells are taking up less glucose to store as glycogen. The pancreas responds by producing more insulin (more grocery stockers), and eventually the liver and the muscles get the message and respond appropriately.

However, fat is the last tissue to become insulin resistant. The original insulin/grocery stocker continues to allow triglycerides to be stocked into fat cells. When extra glucose is present in the blood, the insulin/grocery stocker allows some of the extra glucose to be stored as fat in the fat cells, too. So far, so good. But when the pancreas decides that our bodies need more insulin to function properly, the insulin/grocery stockers won't let customers take very much back out of the fat cells. Fat inventory increases, but is unavailable to be used by customers that might need it. At this point, insulin is starting to become your enemy.

Insulin--Your Friend and Your Enemy, Part I

Insulin is a hormone produced by the pancreas. It is released in response to food--specifically it is released when you eat carbohydrates or protein. It is not released in response to eating fat, but it does have an important role in the way your body handles fat.

Insulin is a storage hormone. When nutrients are absorbed by the gut, they enter the blood. If allowed to remain unchanged in the blood, these nutrients are somewhat toxic. Insulin is your friend because it promotes the use and storage of the nutrients we eat. Carbohydrate is burned as fuel, stored as glycogen, or stored as fat. The protein you've eaten is absorbed from your gut as amino acids. Insulin promotes the storage of amino acids in the form of other proteins (lean muscle, for example). If there are excess amino acids, those can be used as fuel. Fat is also broken down and then stored in response to insulin. You can think of insulin as the grocery stocker who sees to it that a shipment of food is stored in the proper places rather than rolling around randomly in the aisles.

But what if the grocery stocker develops an attitude? What if he decides not to tell management when new stock has arrived? What if he avoids putting certain items onto their appropriate shelves but leaves them in the aisle? What if he continues to add other items to the correct shelves, but won't let the customers take those items off again? When that happens, insulin also becomes your enemy. More tomorrow.

Stargazey, You Use Hard Words!

That's true. I try to keep these posts brief and to the point. Using specific terminology helps me cover a topic in paragraphs instead of pages.

If you don't understand a word, Google it. One interesting aspect of low carbing is that those who do it, learn to teach themselves all sorts of things.

Or just ask me about it in the comments section. I'll do my best to explain anything that isn't clear in my posts.

Welcome Jimmy Moore Readers!

Jimmy Moore at Livin' La Vida Low-Carb has kindly referenced my blog, and I thank him for it.

As he said, I'm not giving much information about myself here. That's because I don't want anybody to say, "She's _____ (fill in the blank), and that's why she can do low-carb and I can't."

As long as your doctor has said it's medically safe for you, anybody can do low-carb. After you have survived the "Atkins flu" of induction, you will start to feel better and your health will improve. Then you'll start to look better, and you'll be even more motivated to do low-carb for the rest of your life.

Welcome to the journey!

Good Fats, Good Proteins

Carbohydrates, fats and protein are all macronutrients, i.e., the part of our diet that provides energy and the building blocks our bodies use for growth and maintenance. If we don't need to eat carbs, what macronutrients DO we need to eat?

Good fats and good proteins.

Good fats are (obviously) not the transfats. We also have to be careful with mono- and polyunsaturated fats, found in liquid vegetable oils. These become rancid within days to weeks and turn into forms that cause oxidative damage to our bodies. A better choice is the saturated fat found in animal fat and butter. An even better choice is the medium chain triglycerides found in coconut oil.

Good proteins are complete proteins. Proteins are made of long chains of amino acids. We can make some of the amino acids through intermediary metabolism, but some are essential amino acids and must be taken in as food. Excellent souces of complete protein include eggs, whey protein, cheese, meat and fish.

You Are NOT What You Eat

Intermediary metabolism is another difficult term that helps us understand how low-carbing works. Let's break it down:

inter - between

mediary - acting

meta -change/transform

bolism - placing


The idea is that we have a process acting between one thing and another, transforming or changing the thing from one form to another form.

Intermediary metabolism describes the hundreds of biochemical reactions that take place in our bodies every second. Through intermediary metabolism, the food we eat is transformed into energy. Through intermediary metabolism, our food is also transformed into new molecules that are then used to make up cellular organelles, cells, and tissues. Although all of the biochemical reactions are now understood in great detail, we can think of intermediary metabolism as the black box that takes the nutrients we eat and transforms them into the structures of our bodies and the energy we need to run them.

For those who would like a simplified overview of the process of intermediary metabolism, here is an illustration found in the Elmhurst College Virtual Chembook by Charles E. Ophardt.


People like to say, "You are what you eat." That sounds right, doesn't it? But if it were true, the prototypical policeman would resemble a Krispy Creme. The vegetarian would look like a stalk of broccoli. Why don't they? Because of intermediary metabolism. Within certain limits, our bodies are able to take in what we eat, break it down into pieces of molecules, and build it back up into the molecules we need to build and to run our bodies. In other words, intermediary metabolism is what makes us what we are in the physical sense.

Because of intermediary metabolism, the fat we eat does not have to become fat in our bodies. It can be burned as fuel. Because of intermediary metabolism, the cholesterol we eat does not have to become cholesterol deposits. It can be incorporated into cell walls to make them less rigid. Because of intermediary metabolism, the carbohydrates we eat can easily be transformed into energy or, if conditions are right, turned into fat, stored, and locked into storage.

Bottom line: You are NOT what you eat.

High Carbs/Low Fat--Not Such a Good Idea

A book that has changed my life is Gary Taubes's Good Calories, Bad Calories. In this book, Taubes explains how Ancel Keyes hypothesized that high fat and high cholesterol produce heart disease. By carefully picking their data, and controlling who was allowed to be influential in the scientific discussion, Keyes and his colleagues were able to persuade the American medical community that carbohydrate should constitute 70% of our diets and we should eat no more than 15% fat.


When Americans began increasing carbs and decreasing fat, heart disease did not decrease. Obesity, however, increased. Experts said that Americans were exercising too little. Americans started exercising more, but as they continued to eat high carb/low fat diets, they continued to get fatter. The graph above comes from the Centers for Disease Control, National Center for Health Statistics. Look at the line labeled "Obese, 20-74 years." In the 1970's, about 13% of adult Americans were obese. By the early 1990's it was about 21%. By 2000, about 31% of adult Americans were obese. In subsequent posts, we may be able to gain some insights into the reasons for this trend.

Why Limit Carbs?

There are several reasons for choosing a low-carb lifestyle. One of them is that our bodies don't handle large amounts of carbohydrate very well.

Consider our hunter-gatherer ancestors. They obtained most of their calories from hunting and fishing, which provided both protein and fat. But their carbs came primarily from nuts and fruit. It takes a long time to crack open and eat a significant number of nuts. In pre-agricultural days, fruits were small and seasonal. If our ancestors were to survive, their bodies had to be able to convert the nutrients found in protein and fat into everything needed to sustain life. And sure enough, all the biochemical pathways are present in our bodies for that to happen.

Agriculture has only been a significant factor for the past 10,000 or so years of human existence. Agriculture is what has made large amounts of carbohydrates available to us. And, unfortunately, our bodies have not adapted very well to abundant carbohydrates.

(The man in the picture is a descendant of the ancient hunter-gatherer "San" people in the Kalahari. Photo by South African tourism.)

How Much Carbohydrate Do I Need?

Not much. Carbohydrates can be used by our bodies for energy. But so can fat and proteins. Any cells that contain the little organelles called mitochondria are able to use fatty acids (which come from fat) and ketone bodies (which are made from fatty acids and from the ketogenic amino acids in proteins*) for energy. In fact, some tissues prefer non-carbohydrate energy sources.

There are only a few tissues in the body that must use carbohydrates as their energy source--some parts of the brain, some kidney cells, red blood cells and the cornea of the eye. These tissues will use about 40 grams of carbohydrate per day, which is well within the margin that can be produced by gluconeogenesis in the liver.

*Corrected from the original version. Thanks to Hans, in the comments.

Gluconeogenesis

Gluconeogenesis is a big word, but it's important because it's why low carbing works. Let's break it down:

gluco - glucose (a carbohydrate)

neo - new

genesis - to make


Gluconeogenesis means "to make new glucose." It's a process that happens in the liver. The liver uses a set of enzymes to take the glycerol backbone of lipids or amino acids (the building blocks of protein) and convert them to glucose. People will often tell you that you need to eat carbohydrates to be healthy. You don't. In fact, if you ate nothing but protein, your body would be able to make about 400 grams of carbohydrate every day from the amino acids in that protein. (Not recommended, of course, but it's theoretically possible.) More tomorrow.

(The picture is from the Elmhurst College Virtual Chembook by Charles E. Ophardt.)

Who Am I?

I'm a woman who has done Atkins 2002 for five years.

I've gone from a size 22 to a size 6.

Do you want to feel better and look better than you do today? Come join me in the low-carb lifestyle!

By the way, I'm also an inveterate blog-tweaker. If you read something here one day and find that it reads a bit differently the next day, don't worry that your memory is failing. Sometimes I'll reread a post and decide that I could have expressed myself better, so I'll change it. I don't usually point out the changes because I'd rather not distract from the point I'm trying to make. Now, back to low-carbing and why it works.)

Welcome!

Hi! I'm new to blogging, but not to low-carbing.

I'd like to provide a place where others can learn to low-carb.

Welcome to the journey!