(This post is directed to detractors of a low carb - high fat approach.)

"A calorie is a calorie" lie. Our body burns, uses, and reacts to different forms of energy differently, and to view each calorie equal is not an optimal strategy for weight loss.

Your body is a furnace. Everything which facilitates and defines your existence as a living organism, from the cooperation of your bodies muscles resulting in a vigorous sprint, to something as basic as your heart beating while you sleep all require fuel. Your body has two types of fuel, glucose and lipids/ketone bodies. Carbohydrates and protein are broken down into glucose, fats are broken down into ketones.

Carbohydrates come from many different sources. Unlike fats and proteins, carbohydrates can be very different on a molecular level from one another. For example, stripped and refined white sugar or white bread on a molecular level much more closely resembles pure glucose than does unprocessed and unrefined fresh strawberries. How closely a carbohydrate resembles pure glucose is tracked in a system called the glycemic index (or glycemic load, which considers average portion size). The more molecularly close to glucose a food item is, the easier it is for your body to break it down into glucose. Eating high glycemic carbohydrates as a dietary staple are bad for three reasons:

1) They are easy to break down to usable fuel, which means your body expends very little energy doing so. Since your body requires less energy to create energy from these types of carbs, you cannot eat that many calories before you have "overeaten". Though overeating fat is worse than overeating carbohydrate, it is in practice much easier to overeat on carb than overeat fat.

2) Because simple and processed carbs are so easy to break down for fuel, you are met with a "fuel rush" into your bloodstream once ingested. You feel elated, satisfied, lethargic and tired. This is known as a blood sugar high, or hyperglycemia. This rush of fuel is quickly met with an equally large rush of insulin, brining your b:s low again, known as hypoglycemia. You feel irritable, shaky, weak, and ravenous. The cycle repeats itself. Unstable blood sugars are ultimately behind the epidemic of overeating.

3) The perils of excessive carb intake does not stop there, though. As i said, after blood sugar rises very high from eating, say, a huge bowl of pasta, your body produces an equally large dose of insulin to attempt to balance your blood sugar. Now, insulin is a hormone which encourages your body to store food it has taken in as fat on your body, and it will sacrifice biological function to a degree so it can.

There is an evolutionary reason for this. In an evolutionary response to environmental factors, nature (the network of all species on earth) works together in cycles of youth (summer), old age (fall), death (winter), and then rebirth (spring). The way your body reacts to different food sources is an evolutionary response to this "seasonal" natural environment. Lipids are the fuel source for the hard times, carbs and protein are fuel sources for the good times. Your body evolved to react a certain way to the presence of very high blood glucose levels. It thinks, "wow, fruit stuff must be really plentiful, lets store as much of it as we can for the winter!". Thing is, most human cultures have defied nature. "Rough winters" are no longer a reality for people, and that carbohydrate induced stored fat is fairly useless. Living in an eternal period of biological prosperity means the fat is never burned off, so the cycle just keeps repeating as we eat more high gi carbs, and more fat is added on.

This is why low carb works so well. Though i will not argue, it is important to watch calories, it is also important to watch what kind of food we eat. Since we are members of a prosperous species, unless we wish to suffer a lifetime of crippling obesity we must restrict the % of calories which comes from our "prosperity fuel source" intake. We no longer need to store food for the winter, which is what carbohydrates (and protein, to a lesser degree) does, as it is always a figurative summer.

Since in our natural environment, your body will actually elect to use dietary or stored fat as fuel only during times of hardship, fat is broken down slowly and does not cause b:s spikes.
The minimizing or elimination of b:s spikes eliminates hypo/hyperglycemia, which encourages healthy caloric intake. The minimizing or elimination of high insulin levels discourages the conversion of dietary food intake to physical fat stores on the body. Your body sees the lack of "prosperity fuel" and reacts appropriately: "gosh, times must be hard, don't be a pig, take and use just what you need, nothing more".

A low carb - high fat diet is the key to weight management.

Good post. To add to the above...the kcal/g used by the government is incorrect. It is based solely on how many calories your body gets from a given macronutrient. It does not take into account how many calories are expended breaking down that macronutrient.

Fat has a true caloric value of closer to 5 kcal/g, not the 9 kcal/g used by the government. I'm not sure what Protein's true caloric value is, but I know it is virtually nill. Carbohydrates [especially Hi-Glycemic ones] are very easy to break down and thus have true caloric values close to their government assigned value of 4 kcal/g. Fiber has a true caloric value of 0 kcal/g...and for once the government agrees setting the caloric value for Fiber at 0 kcal/g.

Polyols can vary. I'm not sure of the true caloric values, but the government sets the caloric values indiviudally and they can range from 0.2 kcal/g (Erythritol) to 3.0 kcal/g (Hydrogenated Starch Hydrolysate/Maltitol Syrup.)

If Fat, Protein, and Carbohydrate calories were listed at their true caloric values, a T-Bone steak would have a caloric value closer to 300 Calories, and a Prime Rib would be around 500 Calories. A filet of Catfish would have a true caloric value of less than 50 Calories. Foods with fat in them wouldn't be so quickly shunned if the calories listed accurately reflected calories contirbuted minus calories expended breaking the macronutrients down.

cc, do you have an online link for this information? I'd like to be able to pass it on to someone else, but I'd like a more official-sounding source than "Something I read on a low-carb support website."

I'm not sure I believe the metabolic advantage of a low-carb diet myself, not having been inclined to weigh my food to the gram before eating. Maybe I lost 45 pounds by calorie restriction and not metabolic advantage -- but I'm surprised it was as easy as it was, if that was the case.

I believe I read the first part [about Protein having little true caloric value] in "The Paleo Diet." I don't remember for sure where the fat value came from. But, I will try to find it and post it here if I do.

guys,
this is not true. you can not change the laws of physics. if a substance, say a gram of fat, contains 9 kcals, then our body will have 9 kcals more potential energy, once ingested.

Here is another basic law of physics: No energy source (as of yet) is 100% efficient. Think about it this way: You have a car that runs on hydrogen (ketones). To obtain that hydrogen your car must break down water (fat). The process of breaking down that water (fat) requires your car (body) to expend some fuel (kcals). A fuel may return more energy than is expend utilizing it [as fat does]...but, no fuel returns ALL the energy spent utilizing it.

hi cc,
you may be referring to the 2nd law of thermodynamics, which states that not all the heat energy of a substance can be converted to work, because we cannot capture the random kinetic energy of atoms/molecules.

however, i don't think this applies in our case here, at least not in the amounts to which you refer, namely that 9kcal of fat is actually only 5.

for example, our car engine is not totally efficient, in that part of the gas burned is used to power the pistons, and such, that make the car move, while most of it is lost in heat and exhaust, but it can still be accounted for.

within the body, all catabolic (breaking down of nutrients), releases heat. that fat, once ingested, gives the body 9kcal greater potential energy. it is within a closed system (the body). energy can be transformed from 1 source to another, but it can not disappear.

Calories are a very good reference for setting the amount of food to eat.

It won't say much about the ratio of proteins/fat/carbohydrates, but it remains my base for the overall daily intake. And it works.

Fortunately, many authors and doctors do not agree with you - and have done the research to back their claims up.

Barry Groves and Eat Fat, Get Thin

OPTIMUM SPORTS NUTRITION, Dr.Michael Colgan

Pi-Sunyer FX. Effect of the composition of the diet on energy intake. Nutr Rev 1990;48:94-105

Colgan M.Your Personal Vitamin Profile. New York:Morrow, 1982.

Even my 2nd year Chemistry book (which deals with nutrition and health) states that calories from fat are not completely used by the body...
So I don't think the 2nd law has much to do with it!
It's more to do with the energy that is used to break fat calories down to substances the body can use.

S

hi natrushka,
i am sorry. on this you are wrong. however, if you read the article to which you referred me, it does not negate what i am saying.

adding 9 kcal of energy to your body, does indeed give the body 9 kcal more of potential energy.

it is a different argument all together, if you want to argue as to what the body does with it. in his example, the other 4 grams went to building of a ketone, which now has 4 kcal of potential energy.

you can not go against the law of physics, no matter how much you want to rationalize. energy is transformed, but not disappeared. it has to go somewhere, either as heat, or as another nutrient. if you want to side with some low carb doctors, that is fine. i have einstein, and all the great physicists on my side.

i never said that everything ingested is used by the body for energy production. if we are eating properly, protein and essential fats are used mostly for anabolic purposes, while carbs and saturated fat are used mostly for the creation of energy, so that our bodies can perform our anabolic processes, and give us our mobility.

fortunately, there is one person here who does understand physics, and knows that energy can not be created, but rather transformed into other kinds of energy.

you might also recall that i have never come here, touting "number of calories". what i have said is the following : make sure you get ample protein, ample essential fats, and the rest is good carbs.

now perhaps you can understand why i said this. ample protein and essential fats for our anabolic processes, while the good carbs gives us our energy, our phytonutrients. this is the basis for "optimum health".

gymeejet:
Do you measure the caloric value of your faeces or urine?
You need to take into account energy going out of the body too if you want to stick to your Calorie is a Calorie routine. I excrete ketones - lots of them - in my breath and urine. Therefore I am getting rid of unused chemical energy.

Anyway your calculation is wrong. 4 kcal went to the supporting processes for production of the ketone. This ketone has more than 4kcal of energy though - it has the energy of the fatty acid residues that go to make it up. The 4 kcal that got used to MAKE the ketone are lost to the body - can't be reclaimed!

Gymee, I never meant that energy is destroyed. The basic laws of physics say energy can be neither created nor destroyed. Here is what I was saying in a nutshell: Fat provides 9 kcal/g. But, in order to convert that Fat to Ketones [which your body can use,] your body has to expend 4 kcal worth of energy. Think of it as a 4 kcal boost in your Metabolism.

You can put the 4 kcal on the expenditure side if that helps. For each gram of fat your body uses, it must expend 4 kcal of energy. This energy is lost [from the body] in the exact same manner as if it had been expended through your Metabolism or by Exercise.

Think of it like this: Calories in - Calories out = Net Calories. The problem is we are not counting all the Calories out. We need to include those Calories expended breaking fat down into Ketones, those expended breaking Protein down into Glucose, and those Calories that are locked up in body tissues such as muscle. If you count these calories as Calories out, then you will see that eating fat increases the Calories out, thus reducing the Net Calories. Not only that, Fat and Protein provide more satiation, possibly reducing the Calories in.

On top of all this, if you do not have insulin to store the excess calories as fat, they are broken down [in the case of fat] and permenantly excreted from the body. Therefore, a low-carb/hi-fat diet works by dramatically increasing Caloric expenditure. It's still calories in/calories out. Nutritionists don't seem to grasp the idea that Calories can be expended by means other than exercise.

hi cc,
in the case of exercise, we create heat energy, which of course we lose, as we sweat. are you saying that we create more heat energy, from burning fat, than we do from burning carbs ?

whenever i have seen chemical equations for catabolic transactions, heat is shown only as an output.

one thing that we also need to realize is that all chemicals in the body are eventually burned as fuel, or excreted as waste. so all that energy that we intake, must be accounted for, at some point. so even if our body does not break catabolize the essential fatty acid at time of ingestion, it will at some point, get rid of it, so that potential energy is still there.

but i do not believe in the calorie concept, as far as health goes. i just chuckle a bit at what i find to be a rationalization for eating more of it. the bottom line is that we all need to find the correct amount of anabolic/catabolic nutrients that our body ultimately desires.