This is partially correct, but your mistake is focusing on the insulin, and not the sugar. The energy from sugar is what causes the "energy rush", insulin merely facilitates the process.

Insulin has zero positive/increasing effect on the rate at which energy is used. While it is true insulin is a necessary component for metabolic activity to occur, in that it regulates the usage of sugar, but apart from this necessary function it does not cause an INCREASE in the rate of metabolic activity at all. It is by its nature neutral in how much or little energy is burned, it merely facilitates the processes. In fact, after a long enough time, insulin causes metabolic suppression, and I will explain why. Here is how it works.

First a brief introduction to IR. Insulin resistance is basically how sensitive your body's cells are or aren't to the effects of insulin. A young and healthy metabolism has no problem handling sugar and keeping energy balanced, even when dietary composition is very rich in sugars and starches. This is because the body's cells are receptive to the effects of insulin, and degree of insulin resistance is very low. Things are fine for a long time.

After a long enough time of this kind of diet, eventually your cells' ability to respond to insulin begins to decline. Basically, what body is doing is inducing insulin resistance on itself to protect from premature cellular aging/death. By eating a high sugar diet, you are exposing the body to an abnormally high flood of potential energy that it must deal with via metabolic activity. Metabolic activity causes aging; living causes dying (shocker eh?). Insulin resistance - making energy using tissues less sensitive to the reception/usage of energy - is the survival mechanism your body developed to protect itself from premature cellular death. Insulin resistance itself contributes to a whole host of other problems when sever enough, but it is important to remember that IR is to your body a last-ditch survival mode. Think of your body using insulin resistance to survive in much the same way as a drowning man using his own clothes to stay afloat the rising tides. Even though stripping himself will expose him to hypothermia and kill him that way after a long enough time, he still does it because he has a more immediate threat to deal with (the flood of water). SO it is the same with your body. Even though IR will eventually kill you (uncontrolled type 2 diabetes), your body sees it as a necessary action that must be taken to deal with a more pertinent threat (threat of cellular death).

Now that that is out of the way, let me explain why insulin - a hormone that starts out neutral to metabolic rate, eventually contributes to a decrease in metabolic activity.

I already explained what insulin resistance is, and why your body does it. It is important to also know that not all cells are the same, and some types of cells are more readily prone to become insulin resistant than others. As I said, your body uses insulin resistance as a survival mechanism to protect itself from abnormally high metabolic rates. These metabolic rates aren't caused by the insulin itself as you claim, but they are caused by over eating sugar. The flood of sugar = flood of energy = more demand on metabolism/cellular activity.

Your body intelligently selects which cells to make insulin resistant, and which cells to leave more insulin sensitive. Cells that are more likely to spend energy (i.e. muscle tissue) are the most likely to become insulin resistant. Fat cells are generally the last to become insulin resistant. Like I said, your body does this for a reason - it makes energy using tissues more insulin resistant before others, so as to prevent premature cellular aging/death. What your body is doing is trying to HALT the continuous flood of energy it is being exposed to, as this high sugar/energy will cause early cellular death. Therefore, your body is most likely to make cells with the highest metabolic expense the most insulin resistant, and fat cells the last to become insulin resistant. This is because fat cells have the least net metabolic expense; for every bit of energy they burn, they also preserve some.

Now imagine this with me: pretend your body is a sieve, and each hole of the sieve represents clusters of body cells. Pretend each hole in the sieve of your body is a different size, and how small/large the hole is = how insulin resistant that particular cell is. Fat cells are represented by larger holes, and LBM is more accurately represented by the smallest holes. Pretend sugar is the water. When you pour water (carbs) into the sieve of your insulin resistant body, here is what happens. The water will more easily fall into the fat cells than the muscle cells. Because the water can't get into the "energy using" holes effectively any more, a greater and greater percentage of the water will go into the less insulin resistant "energy sparing" holes (fat cells).

The result? Very insulin resistant people who eat a high sugar - low fat diet will experience the following unfortunate symptoms.
1) Fatigue and low energy levels. This is because the body cannot effectively utilize the energy you are giving it for vital metabolic activity. Your body responds to this by drastically lowering basal metabolic rate and making you feel tired sleepy and sluggish so you are less likely to increase demand for energy via activity.
2) So what happens to all that energy then that you can't use? Easy. It goes where it can go, the relatively insulin sensitive cells: the fat cells. Making you fat.

This is how it is VERY possible for an extremely insulin resistant person to gain weight on a 1000 calorie a day diet, if the composition of that diet is all wrong (i.e. high sugar and low fat).

Where do you go from here if you don't change what you are doing? Simple. Diabetes occurs eventually. First what happens is type 2 diabetes. The muscle tissue and the fat tissue have become so extremely insulin resistant, that even the very high insulin levels your pancreas is already churning out just isn't enough anymore. The sugar quite simply has no where to go because your body refuses to deal with it. Blood sugar levels are through the roof, and you are losing large amounts glucose through the urine. Starved for energy, your body starts to cannibalize itself and you become ketogenic at the same time as having extremely high blood sugar. You are losing weight rapidly. You are also extremely thirsty and can't hold to any nutrients including liquids (insulin also regulates fluids and minerals and the like). This is the danger zone. Your life hangs in the balance. If you don't get medical attention soon to help control your sugars, you will eventually go into a diabetic coma and you will die.

Sometimes you can also become type 1 after a long enough time of being type 2. If you have a particularly strong pancreas, you may very well be able to handle the demand for insulin your insulin resistant body cells require. Your insulin levels will be through the roof, and trouble is certainly lurking around the corner, but your symptoms right now may very well be minimal. However, even the strongest beta cells will burn out after awhile. If you don't do something to reduce the demand for insulin, you may eventually lose the ability to make it and have to depend on synthetic injections.

*whew* that was a lot of typing. Anyway, I hope I have clarified this confusing subject.

Basically, insulin definitely doesn't cause an increase in metabolic activity, nor is it truly accurate to say insulin causes a decrease in metabolic activity (although this is certainly more accurate than the former, because insulin in high levels lowers energy-transforming metabolic activity as describe above. However, even insulin isn't the cause in this case, as its presence is reactionary). Insulin is by its nature neutral, it does what is needed of it.
It is the sugar. It's always been the sugar. Insulin simply regulates the flow of energy/sugar, how it is spent and used. It is a traffic cop. Blaming insulin for IR/diabetes/etc is like blaming a traffic cop for a traffic jam because the streets are congested with too many cars. Blaming insulin for the excessive flood of energy caused by YOUR dietary choices is equally as foolish.

Your body does what it has to do in times of crisis. IR is a necessary evil from a biological perspective.

Regardless of rate, any body warmth we experience is the byproduct of metabolic activity. The energy (calories) in food is used by the body, used and transformed into heat (thermogenic energy). This process of transforming energy from food calories into heat is known as "metabolic activity". You are aware of this, correct?

Knowing this, we can understand why hypothyroid people report feeling abnormally cold - their metabolic rate is low, and because of this they aren't burning enough energy to maintain a normal body temp.

In fact, by recognizing the fact that low carbers often report feeling warmer, you are basically proving yourself wrong. The increase in body temp associated with low carb pretty much offers solid evidence that low carbers raise their metabolic rates slightly, which is why we can afford to consume more energy (calories).


I don't appreciate your rude and condescending tone. I have been doing LC for over a year, and have read all relevant books for my plan. I have done extensive research on the subject via internet, and am quite familiar with the science behind low carbing. What I speak of is the conventionally accepted belief. What you are claiming is not. It is up to you to provide any semblance of evidence to support your beliefs.