The carbs will prevent some of the fat from being mobilized, but the olestra will carry out the pesticides that are already in the circulation as they’re dumped into the GI tract instead of letting them be reabsorbed with the fat.

Just read all the comments on this article. I would agree with most of what is being said. Occasionally I come across a patient who just refuses to lose weight, and by taking them on a high fat very low to no carb diet they do begin to lose weight.

One question which has always puzzled me is this, given that the conversion of proteins and fats to glucose is inefficient, and given that if you do consume large quantities of calories as fat, which are processed through futile cycles, do you generate a lot more free radicals and ultimately do cellular damage? I tend to visualize it as leaving a car engine running while it is stationary. No real function, but the engine still wears out.

Should low carb practitioners increase their relative intake of antioxidants, if they are not consuming significant amounts of organic vegetables. Thank you once again for a great blog.

Hi Tahir–

I don’t think that low-carbers need more antioxidants, and here’s why.

First, they are eating more fat and more saturated fat, so the mitochondrial membrane fats will become more saturated (i.e. have a lower desaturation index) making them less prone to free radical damage.

Second, the greater number of uncoupling proteins and the increased proton leak across the membrane tend to dissipate the energy across the membrane and decrease the likelihood of as many free radicals being produced.  It’s kind of difficult to explain, but imagine with much higher pressure on one side than the other.  As the electrons move down from one complex to the next along the membrane they are releasing energy to increase the pressure differential.  Since the pressure differential is already high, there is more resistance and the electrons are more likely to break out of the system and become free radicals.  If the pressure is constantly being reduced on the higher-pressure side, then there is not nearly as much resistance to the release of energy from the electrons and, hence, the electrons are more likely to continue their course and not bolt from the system and become free radicals.   Hope this helps.

Best–

MRE 

This is in follow up to your answer to Ryan #8

You stated that in a low insulin situation fat can be disposed of three ways, “People can burn more calories by increasing exercise; they can eat fewer calories; or they can increase their metabolic rate. Or they can do any combination of the above.” In the explanation of futile cycles which have to do with the metabolic rate you further state that, “Futile cycles are what give us our body temperature of 98.6 degrees. Futile cycles are just what the name implies: a cycle that requires energy yet accomplishes nothing.” Would this mean that in some people on a high fat, high calorie diet in a low insulin situation that their body temperature would go up, though I imagine to a small and perhaps not measurable degree?

Porter

Hi Porter–

That is indeed what happens.  The increased cycling runs the temp up a little.

Cheers–

MRE 

I have read that this process is fairly inefficient. Does that mean that your protein requirements will go up if you eat very low carb since more of the protein will be converted to glucose (with some wasted in the process)? It seems that if you don’t eat enough protein, your body will cannibalize muscle to get the glucose it needs.

On the flip side though, if you eat extra protein, will all of the excess protein be converted to glucose and will this raise your insulin levels, causing you to store those extra calories taken in as fat, even with no carbs taken in?

Thanks again for your time.

Hi Ryan–

It takes about a gram of protein to make 0.7 grams of glucose, so if your only source of glucose was protein, you would have to eat 100 grams or protein to make 70 grams of glucose.  But you don’t get all of your glucose from protein.  Some comes from the glycerol backbone of the triglyceride molecule.  When dietary fat or your own stored fat is broken down, the glycerol backbone holding the three fatty acids is released and can be used to make glucose.  So, you do need extra protein on a low-carb diet to help keep the blood glucose stable without having to cannibalize your own lean tissue.

The body only converts the protein needed to keep glucose in the normal range, so you don’t have to worry about glucose levels going up and a resultant insulin rise.  Doesn’t happen.

Cheers–

MRE 

Hi Robert–

Thanks.  Somehow I’ve never considered myself imbued with the puritan work ethic.  Who knows why I was inspired on this one.

Cheers–

MRE 

Where does the fat we consume go whilst futile cycling takes place. If I drank a pint of double cream, it would all be absorbed into the bloodstream, rather than going down the pan, correct? As I understood it (from Malcolm Kendrick) the newly absorbed fat is mostly transported as triglycerides in chylomicrons direct to fat cells, bypassing the liver.
Now I read that with low insulin levels, the fat/triglycerides cannot enter fat cells.

So, where does my newly absorbed pint of cream spend the next couple of hours? Does it remain in the bloodstream? I must confess to getting more than a liitle confused, Dr Eades.

Hi Neil–

The newly absorbed fat is transported in the lymphatic system and dumped through the thoracic duct into a large central vein near the heart.  This fat is then in the bloodstream and does go to the cells, but it goes through the liver as well.  The triclycerides probably do go into the fat cells, but then comes right back out if insulin is low.  As the fat goes through the liver in a low-insulin situation it gets partially broken down into ketone bodies.  These ketone bodies are fat that is soluble in blood and are transported to the various tissues that use them.  The tissues extract the ketones they need and break them down to the high energy electrons that enter the electron transport chain (the oxidative part of oxidative phosphorylation) that are then used to pump protons across the membrane in one direction, which then get pumped back causing a dissipation of energy without any real work being done.  Some ketone bodies are released into the breath, others into the urine, and some into the stool, getting rid of even more calories.

Hope this helps.

Cheers–

MRE 

Hi Mmmm–

I have found insulin sensitive obese people, typically women, but they still do fine on low-carb diets.

Cheers–

MRE

On several low carb forums right now, there is a debate going on about what happens to the extra fat calories if carbs are kept extra low so that insulin is kept low. Some say it will be stored as fat anyway, others say it will be burned as heat and still others say it will be excreted. One member even did near-zero carbs and very high fat for a week (4500 calories instead of a normal 2500, with an average of about 80-90 g of protein). He lost a pound off of his already lean physique.

So, where does that extra fat go? Is it excreted? The detractors say that fat is completely digested before reaching the colon but I am not sure. If it is excreted, could you go ultra high fat, zero carb for a week or so and get the same detox results as the cosmic pizza grease?

Hi Ryan–

Your comment raises an interesting question.  Where does all the excess energy go?

I’ve had a number of patients and countless letters from readers who have had the same experience.  They consume a ton of fat, but don’t gain weight…or even, as with the guy you described, lose a little.  Mostly the letters we get are from people who complain that they are following our diet to the letter, yet not losing weight.  When we investigate, we find that in virtually every case these people are consuming huge numbers of calories as primarily fat.  We always ask them if it doesn’t strike them as strange that they’re eating as much as they are, yet not gaining.

In order to lose weight, one must create a caloric deficit.  This can be done in a number of ways.  People can burn more calories by increasing exercise; they can eat fewer calories; or they can increase their metabolic rate.  Or they can do any combination of the above.

Most people going on a low-carb diet decrease their caloric intake.  A low-carb diet is satiating, so most people eat much less than they think they are eating even though the foods they’re consuming are pretty high in fat.  Some people, however, can eat a whole lot on a low-carb diet, and, can in fact, eat so much that they don’t create the caloric deficit and don’t lose weight.  But the interesting thing is that they don’t gain weight either.  They pretty much stay the same.  They are eating huge numbers of calories and not gaining, so where do the calories go?

First, I don’t think they go out in the bowel.  If they did, people would have cosmic pizza grease stools whenever they ate a lot of fat over a period of time, and they don’t. And a number of studies have shown that increasing fat in the diet doesn’t increase fat in the stool.

Eating a very-low-carbohydrate diet ensures that insulin levels stay low.  Unless insulin levels are up, it’s almost impossible to store fat in the fat cells.  With high insulin levels fat travels into the fat cell; with low insulin levels fat travels out.  So, it’s pretty safe to say that the fat isn’t stored.  So what happens to it?

The body requires about 200 grams of glucose per day to function properly.  About 70 grams of this glucose can be replaced by ketone bodies, leaving around 130 grams that the body has to come up with, which it does by converting protein to glucose and by using some of the glycerol backbone of the triglyceride molecule (the form in which fat is stored) for glucose.  If one eats carbs, the carbs are absorbed as glucose and it doesn’t take much energy for the body to come up with its 200 gram requirement; if, however, one isn’t eating any carbohydrates, the body has to spend energy to convert the protein and trigylceride to glucose.  That’s one reason that the caloric requirements go up on a low-carb diet.

The other reason is that the body increases futile cycling.  What are futile cycles?  Futile cycles are what give us our body temperature of 98.6 degrees.  Futile cycles are just what the name implies: a cycle that requires energy yet accomplishes nothing.  It operates much like you would if you took rocks from one pile and piled them in another, then took them from that pile and piled them back where they were to start with.  A lot of work would have been expended with no net end result.

The body has many systems that can cycle this way, and all of them require energy.  Look up the malate-aspartate shuttle; that’s one that often cycles futilely.

Another way the body dumps calories is through the inner mitochondrial membrane.  This gets a little complicated, but I’ll try to simplify it as much as possible.  The body doesn’t use fat or glucose directly as fuel.  These substances can be thought of as crude oil.  You can’t burn crude oil in your car, but you can burn gasoline.  The crude oil is converted via the refining process into the gasoline you can burn.  It’s the same with fat, protein and glucose–they must be converted into the ‘gasoline’ for the body, which is a substance called adenosine triphosphate (ATP).  How does this conversion take place?  That’s the complicated part.

ATP is made from adenosine diphosphate (ADP) in an enzymatic structure called ATP synthase, which is a sort of turbine-like structure that is driven by the electromotive force created by the osmotic and electrical difference between the two sides of the inner mitochondrial membrane.  One one side of the membrane are many more protons than on the other side.  The turbine-like ATP synthase spans the membrane, and as the protons rush through from the high proton side to the low proton side (much like water rushing through a turbine in a dam from the high-water side to the low-water side) the turbine converts ADP to ATP.

The energy required to get the protons heavily concentrated on one side so that they will rush through the turbine comes from the food we eat.  Food is ultimately broken down to high-energy electrons.  These electrons are released into a series of complex molecules along the inner mitochondrial membrane.  Each complex passes the electrons to the next in line (much like a bucket brigade), and at each pass along the way, the electrons give off energy.  This energy is used to pump protons across the membrane to create the membrane electromotive force that drives the turbines.  The electrons are handed off from one complex to the other until at the end of the chain they are attached to oxygen to form water.  (If one of these electrons being passed along the chain of complexes somehow escapes before it reaches the end, it becomes a free radical.  This is where most free radicals come from.)

There are two parts to the whole process.  The process of converting ADP to ATP is called phosphorylation and the process of the electrons ultimately attaching to oxygen is called oxidation.  The combined process is called oxidative phosphorylation.   It is referred to as ‘uncoupling’ when, for whatever reason, the oxidation process doesn’t lead to the phosphorylation process.  Anything that causes this uncoupling is called an ‘uncoupling agent.’

You can see that the whole process requires some means of regulation.  If not, then the electromotive force (called the protonmotive force, since it’s an unequal concentration of protons causing the force) can build up to too great a level.  If one overconsumes food and doesn’t need the ATP, then the protonmotive force would build up and not be discharged through the turbines because the body doesn’t need the ATP.  The body has accounted for this problem with pores through the inner mitochondrial membrane where protons can drift through as the concentration builds too high and by proteins called uncoupling proteins that actually pump the protons back across.  So we expend food energy to pump protons one way, then more energy to pump them back.

One of the things that happens on a high fat diet is that the body makes more uncoupling proteins.  So, with carbs low and fat high, the body compensates, not by ditching fat in the stool, but by increasing futile cycling and by increasing the numbers of uncoupling proteins and even increasing the porosity of the inner mitochondrial membrane so that the protons that required energy to be moved across the membrane are then moved back.  So, ultimately, just like the rocks in my example above, the protons are taken from one pile and moved to another then moved back to the original pile, requiring a lot of energy expenditure with nothing really accomplished.

This is probably all as clear as mud, but it is what happens to the excess calories on a low-carb, high-fat diet.

Cheers–

MRE