Great Questions From a Future Doctor!

I always love when I receive a question from a future doc about proper nutrition. It is exciting to me because I know once I explain the correct way to eat, dispelling the many myths that surround nutritional science, I have just not only educated one person, but the tens of thousands of patients this future doc is going to meet over the course of their career.

As a side note, I have been in practice for 20 years. At about 35 patients a day, sometimes more, never less; I have easily had over a 130,000 patient contacts. Yes, you read those numbers right :-) So just imagine how excited I get given a chance to properly educate a future doc on the right way to eat. His question is italicized below and my answer will follow;


Dear Dr. Jim,



Hello! I recently stumbled upon your blog and found it to be a quite useful source of information. I'm an Army Officer and graduate student headed to medical school next year. One of my major responsibilities in the Army has been to ensure the health and physical fitness of my Soldiers. So I've been trying to gain a better grasp of nutrition science, but much of what I've read I've found to be apocryphal, even from so-called nutrition experts.

In any case, I had a question I thought perhaps you might be willing to answer on your blog. I am curious about the rate and efficiency of food absorption and processing.


In short: if one eats a "normal" American meal made up of protein, fats, and carbohydrates, how long does it take for those excess calories one eats to be absorbed, transported, and stored as fat?


On a related note, how efficient is this process? I'm thinking of this in the context of individuals who are trying to lose weight by lowering their calorie intake. If over the course of the week a person (baseline 2500 calories/day) diets at about 1800 calories per day, but then on one of those days "slips up" and consumes a whopping 6000 calories, is that basically the same as consuming 2370 calories per day over the course of that week or, given the huge volume of food, would some of the nutrients during that 6000-calorie-feast pass through the gut without being absorbed?


Thank you for your time!


Very best regards,


S.W.

Dear S.W.
 
Thanks so much for your intriguing questions about nutrition. Apocryphal is indeed the case when trying to weed through all the hoopla concerning the right way to eat. Over the years I have come to view the term 'nutritonal-expert' as an oxymoron, as most of them haven't a clue about the correct way to eat. Sure, they can recite the glycolytic pathway faster than a match can burn down to their finger; but they really haven't stopped to view the pathways in an integrated fashion, the way these pathways should be viewed. This I attribute to inadequate academic training which still unfortunately persists today, and the tenacious, vehement denial by these 'experts' that we have the biochemical understanding to basically eradicate obesity, type 2 diabetes, heart disease, GERD and many types of cancers TODAY!
 
To understand that plaque-forming deadly cholesterol and fat production starts with a sugar molecule (glucose & fructose), requires an understanding that the pyruvate we arrive at when glycolysis ends and the subsequent acetyl-CoA that's formed, that not all this acetyl-CoA is shuttled into the Kreb's with the oxidative phosphorylation pathway ending it all. No, that's not the case.
 
(Don't worry, I'll get to your questions in a bit :-)
 
I was under the impression when I studied biochemistry & molecular cellular biology in my undergraduate years that it went like this--Glycolysis----Kreb's----Oxidative Phosphorylation---the end. I wasn't told that AcetylCoA is a pivotal bio-molecule and while it can be shuttled to the Kreb's, there were indeed other fates for AcetylCoA. Like condensation of 2 AcetylCoA molecules to get acetoacetyl CoA the starting point for both cholesterol and fatty acid synthesis. I wasn't told that insulin actually acts to increase the creation of HMG CoA reductase by increasing its actual gene expression, thereby creating more of this rate-limiting enzyme, the end result being production of more cholesterol.  While I knew the biochemistry behind the creation of fatty acids and I knew it started with , once again, acetylCoA; the integration of all the possible fates of acetylCoA were not taught to me; I had to put that all together myself many years later as a practicing physician. On top of all this, it was never really stressed to me that insulin performs many different biochemical activities in our cells.
 
Sure, everyone knows insulin is needed to get glucose inside the cell, but as I mentioned above; who remembers that insulin increases HMG-CoA reductases's actual gene expression; that insulin allosterically activates acetyl CoA carboxylase (via dephosphorylation of the enzyme) stimulating an increase in free fatty acid production; that insulin works via a second-messenger sysytem and that one of these messengers DAG (diacylglycerol) has an arachidonic acid side chain that when undergoing degradation helps gives rise to inflammatory and cancer causing mediators and the list goes on and on. In fact, I refer to insulin as 'the dirty little hormone' in my book. Sure, we need it to survive, but very little of this peptide hormone is needed for optimum health...very little.
 
So let's get to your first question...
 
In short: if one eats a "normal" American meal made up of protein, fats, and carbohydrates, how long does it take for those excess calories one eats to be absorbed, transported, and stored as fat?
 
In short, it takes about 8-10 hours for our bodies to create and store fat. When a mix of food is eaten in a 'typical' American diet, it is almost always an overabundance of carbohydrates. Now we need to understand that ALL carbohydrates no matter their source, are broken down into the simple sugar glucose and it is glucose that gets stored as fat in the fat cell or adipocyte as it's called. To create & store fat requires the presence of insulin which will activate the acetylCoA carboxylase enzyme as mentioned above encouraging the biosynthesis of fatty acids with the subsequent storage in the fat cell.
 
Hence, overeat carbohydrates in any form and I mean ANY form, such as whole grains, multi grains, 7-grains, whole wheat pasta, brown rice, fruit (fructose gets stored quicker than glucose as it needs LESS modification) yogurt or oatmeal and you will create and store pounds and pounds of fat.
 
But wait, i hear some of you yelling...'What about glycogen? Doesn't the body create glycogen stores first and then go on to store the excess as fat.?!?!'
 
While that is true, the typical American diet is so overloaded with carbs that all the signals for fat storage are set into play. That is, eat too many carbs (easy to do), secrete insulin, glucose gets shuttled doen the glycolytic pathway, more acetyl CoA is created, more substrate that acetylCoA reductase has to work with and since insulin has been secreted by the carb laden meal, increased activity of acetylCoA reductase occurs.
 
Said bluntly-Eat too many carbs, in any shape or form...get heavier. Did I forget to mention that while over eating carbs will increase your creation and storage of fat; it will also result in the increased production of plaque-forming deadly cholesterol as well. So, in a nut-shell; eat more carbs, you get heavier and increase your risk not only of heart disease but many other disease-processes.
 
Let me also state the fact that ALL one's carbohydrate needs can be met by eating protein, fat & cholesterol containing foods, without the need to even consume carbs. Of note, the glucogenic amino acids, as well as the glycerol backbone chain from triglycerides can be used to create glucose; there are also many examples of societies that eat predominately fat and protein and have low rates of heart disease, type 2 diabetes &cancer (the Inuits are such an example), despite the fact that they are eating what the 'nutritonal experts' around the world tell us not to eat.
 
Ahhh, you have mentioned my all-time Nemesis....The Calorie!
 
Arrrrgggghhhhh!!!!!!!
 
As chapter 6 in my book states "Calories are irrelevant in Human nutrition." Remember that a calorie is defined as the amount of heat needed to raise the temperature of 1 gram of H20 by 1 degree Celsius and that the calorie is important only if you are a heat biochemist. The calorie is measured by a combustion process. When we eat a piece of meat, it doesn't go into our stomach and burn (via a combustion process) it is 'digested' and I cannot emphasize enough that combustion and digestion are two entirely different processes.
 
Now when we eat excess 'calories' we are really not overeating heat (sounds kinda silly when I put it like that), we are overeating carbohydrates; and it is these carbohydrates in the form of glucose that the body will store. Our bodies don't store calories, we store glucose biochemically altered into fatty acid molecules. It took me a very long time to understand the calorie is irrelevant in human nutrition and to this day I'll slip and use the word burn or whatnot; but please always remember that counting calories are an utter waste of time, a red-herring at best.
 
Which of course all this talk about that nefarious calorie is a nice segue into your next question...


On a related note, how efficient is this process? I'm thinking of this in the context of individuals who are trying to lose weight by lowering their calorie intake. If over the course of the week a person (baseline 2500 calories/day) diets at about 1800 calories per day, but then on one of those days "slips up" and consumes a whopping 6000 calories, is that basically the same as consuming 2370 calories per day over the course of that week or, given the huge volume of food, would some of the nutrients during that 6000-calorie-feast pass through the gut without being absorbed?

Seems like a loaded question. Reminds me of those algebraic problems I saw in high school..."if Jimmy is on a train headed north-northwest at a speed of 60 mph and a tail wind is hitting the train at 5 mph, but Jimmy is hopping backwards on one foot in a cross diagonal pattern, how long will it take before Jimmy's gastrocnemius claudicates....?' Huh?

Alright, back to the question.

Since we just learned calories mean nothing in human nutrition, we can just multiply all your numbers by 0 to get 0. In other words, once we understand calories are irrelevant and that it is the grams of carbs that are important, the whole question itself becomes irrelevant. You see, we aren't storing calories at all, but the simple sugar glucose from the carbs. Sure, one can place the food items in question which comprise the calories mentioned into a calorimeter, burn it and see how much heat is being given off; it will tell us nothing about what is really happening in human nutrition, specifically with weight loss.

Let's use a clinical scenario. It took me awhile to realize that my morbidly obese patients actually increased their calories before weight loss kicked in. I didn't realize this because I was focused on carb intake, not calories. The patient who brought this to my attention was over 500 LBs and came in all distressed one day. When i asked him why he told me that he was consuming 4x the amount of calories he was consuming before (2500 to now 10,000 a day!) and his problem was that he was wondering Why he was LOSING weight?!


He confessed he did not increase his exercise at all and despite quadrupling his caloric intake HE WAS LOSING WEIGHT!!!! This was my Eureka! moment when I started to actually count calories and carbs on my patients. What was actually happening is that in my morbidly obese patients, they were often doubling, tripling their caloric intakes before they saw an appreciable weight loss, but they were not increasing the calories via carbs, but by the consumption of more fatty & cholesterol containing foods. As weight loss progressed, the calorie intake was lower and lower, but the calories always took the form of more fat, cholesterol & protein, NOT carbs.

Ask any morbidly obese patients and they'll tell you flat out "I've tried everything, even starving myself and I can't lose weight." Most obese patients do calorie restrict, but since calories mean nothing the end result will be failure; and those who do lose weight, since they almost always are eating a non sustainable low fat low cholesterol diet, will fall off this dietary path, having to start all over again, unfortunately oftentimes still thinking they are heavy due to over consumption of calories and fat.

So for your patients who say, eat 6000 calories a day up from say the 1800 or so, it all depends on what they ate exactly. If those calories were mainly in the form of carbs, they will store and gain weight; if it was in the form of more fat and cholesterol, the biochemical signals will not favor storage and they will not really see an appreciable weight gain if any. And that is why to answer that question we need to know exactly what the foods were that got the person to 6000 calories.

Hope that helps!

Hey, my fingers are getting tired and I have to get a few low carb beers on ice so I can watch the Giants win the Superbowel in a couple of hours!

I hope my explanations helped not only for your personal understanding, but to make and keep our troops the healthiest in the world! Thanks again for asking some very important questions about human nutrition! And CONGRATULATIONS upon your acceptance into Medical School, maybe I'll be teaching your nutritional biochemistry course :-)

drjim :-)
http://www.drjamescarlson.com/