Myths, Metabolism, and Appetite
Humans have been evolving for the better part of 2 million years. During the vast majority of this time, approximately 1.97 million years, we’ve run, we’ve jumped, we’ve swam, we’ve paddled, we’ve climbed, we’ve crawled, we’ve thrived. The adaptability our genome has given us has allowed us to survive in every environment we’ve encountered up until now. Recently, technology has allowed our environment to evolve much more quickly than our genes allow us, leading to an epidemic of obesity and Type 2 diabetes. This epidemic costs the country nearly $300 billion per year.
It’s not terribly difficult to identify the aspects of our environment that have led us to this epidemic. A clever primate that has flourished in environments where food is scarce and physical activity is a requirement to find food is not suited to an environment where physical activity is optional and food can be attained quite easily. This primate has been naturally selected over the course of millions of years to eat when food is available and to exert as little energy as possible to get that food. Now that the environment allows this very thing, we are getting the product of that gene/environment interaction and it’s not pretty.
All is not lost, however. There is quite a bit one can do to turn this predicament around, we just need to be that clever primate and look deep within science for solutions. Unfortunately, our current course is both not working and, when you look at what the science shows, actually driving us deeper in to the hole that we’ve dug. In part 1 of this series we will discuss how the conventional wisdom being passed off to you by your doctors, trainers, and the popular press is all wrong. In part 2 of this series, we will discuss how your metabolism works and how this runs counter to what they tell you. In part 3 we will discuss diet and the science behind why we continually fail.
When you go to your doctor and present as obese or overweight, their standard of care is to tell you to eat less calories and burn more. For most people this does not work, and in a good chunk of the people that it does it only works in the short-term, eventually leading back to the same weight or even worse, more weight gain later down the line. Much of this, as well as nearly all processes in the body, is driven by hormones. Hormones are chemicals that the body uses to communicate between systems. We can use what we know about hormones to control many things related to weight such as appetite, energy levels, stress levels, and fuel selection. Telling someone to count calories and burn more completely ignores these hormonal shortcuts, making the task of weight reduction and maintenance much more difficult. Of the advice that you are given, there are 4 key notions that mislead people down the wrong path: A calorie is a calorie, burn as many calories as you can, carbohydrate is the body’s preferred fuel source, and whole grains are good for you,.
A Calorie is a Calorie
Before we go on, it is important to say that, of course, a calorie is a calorie, what else would it be? The problem with this notion is that it is irrelevant to the discussion. For one, we can all agree that ammunition is ammunition, but a BB pellet and a bazooka shell are not the same thing. They may share a few common traits, but for the most part we can all agree that they probably have more differences than similarities. In much the same way, the calories you consume are quite different from one another based on their source.
Most people look at their food as energy and that energy is measured in calories. What most people don’t realize, however, is that we do not even use our food for energy, we use a substrate called ATP (Adenine Triphosphate). All of our cells use ATP for energy, and ATP is stored within our cells and recharged with the food we eat. As such, there is no calorie receptor on your cells, and your cells do not look at what you consume as calories, it views it as raw materials. Once the food you eat is broken down in to amino acids from protein, glucose from carbohydrate, and fatty acids from fat, it can enter your cells. The kicker here is that not all of what you eat is used for energy. All of it can be used as energy, but your body uses amino acids to build structures and enzymes to catalyze reactions and fats to build hormones and repair cell walls on top of what they provide for energy. Certainly these proteins and fats contained energy when you consumed them, but if you are not using them for energy purposes, do we really concern ourselves with the calories they contain? But wait, it gets even more interesting.
A nutrient is considered essential when the body needs it but cannot manufacture it from other nutrients. Therefore, you need to eat this nutrient directly in order to remain alive. There are essential amino acids, essential fatty acids, but there are no essential carbohydrates. But how can this be? It’s actually quite simple, your body needs glucose which carbohydrates provide, but so can amino acids and a portion of the fat molecule called glycerol. The conversion of non-carbohydrate to glucose is called gluconeogensis and is performed by the liver under the direction of hormones. In fact, for 1.97 million years, gluconeogenesis probably provided the bulk of our glucose needs with vegetables and fruit kicking in as well. Obviously since agriculture became big this has changed, and that is one of the primary drivers of our current obesity epidemic. With the way our bodies work, this could eventually lead to the human genome shedding the genes necessary for gluconeogensis, which would be a bad scene if carbohydrates ever become scarce again.
As mentioned above, carbohydrates are broken down in to glucose and fats are broken down in to fatty acids so they can enter our cells for regeneration of ATP. Amino acids provide energy as well, but only after being converted in to glucose first. But what are the differences between glucose and fatty acids with regard to their energy qualities? The first and most striking difference is that glucose recharges ATP at a much faster rate than fatty acids do.
If you are looking to sprint short distances or perform explosive movements such as jumping, fatty acids cannot recharge ATP stores fast enough so you fatigue once your ATP stores are used up. To perform this type of activity for a considerable amount of time, the bulk of ATP regeneration will come from the breakdown of glucose with fatty acids providing a small amount. Once you stop performing the explosive action or decide to do something more along the lines of long distance running or walking, fatty acids will kick in the bulk of ATP regeneration.
While fatty acids are much slower at recharging ATP, they recharge a lot more of it. The breakdown of 1 glucose molecule will yield 38 ATP while the breakdown of a fatty acid molecule will yield 128 ATP, which is quite a difference. So, while a calorie may be a calorie, are glucose and fatty acids the same? The reactions by which they recharge ATP are completely different, with glucose being metabolized anaerobically (Without oxygen) within the cytoplasm of the cell and fatty acids being oxidized aerobically (With oxygen) by the mitochondria. Given the qualities of each, they seem suited for different goals. Specifically, glucose is a more appropriate fuel source when you need bursts of energy while fatty acids are a more appropriate fuel source when you need a lot of energy but are in no hurry to get it.
Making the “A calorie is a calorie” approach even more frustrating and weak is the fact that as you cut calories your body adapts by burning less calories to accomplish the same tasks. This is true and happens even with no loss of muscle mass(1, 2, 3). So while it is still true that a calorie is a calorie, your body changes the rules of the game by burning fewer calories to do the same thing. Now you need to either cut more calories out of your diet or burn more. By the time you get anywhere near your goal weight you’ll be eating 500 calories a day and exercising 10 hours a week.
The current theory on why this happens is that your body resists burning fat because it is holding on to energy in case of famine. This is a nice theory and all, but if you look deeper it is certainly not the case. Why? Because when you increase your caloric consumption your body adjusts by burning MORE calories, and it can do this to the same extent as lowering metabolism when you lower calorie intake. If the human machine is so concerned with conserving calories, why do the rules change during overconsumption of calories?
Obviously this is an adaptation to the environment and not some uni-directional stress mode that rains on your weight loss parade. Lowering your metabolism is basically your body’s way of becoming more efficient, burning a smaller amount of energy to accomplish the same tasks. Put another way, instead of being able to drive 400 miles to the gallon, now your car can go 500 miles to the gallon. This is a positive thing and a preferred state that most people looking to lose weight do not want to hear because they are preoccupied with counting calories. When you look at the amount of calories you need to either cut out of your diet or burn just to lose 1 pound of fat you’ll probably faint.
Burn as many calories as you can
How many calories do you need to burn to lose a pound of fat? I’m sure all of you have been given an answer by either your trainer or doctor, but I can assure you that the number you were given wasn’t accurate. Most people were never fans of word problems as kids, and they typically carry that distaste in to adulthood. If you look at the questioned I posed, I asked how many calories you need to burn to lose 1 pound of fat. Your answer was probably 3500, which is basically the number of calories in a pound of fat. The problem with this is that it’s not the question I asked. You see, while there are indeed 3500 calories in a pound of fat, you are never burning 100% of your calories from fat.
The largest percentage of calories from fat your body will use for fuelvis 60%. I will not bore you with the math, but this puts the MINIMUM number of calories you need to burn to lose a pound of fat at 5833. Just to give you an idea, a 160lbs male would need to run at 8mph for 7 hours to burn a pound of fat at that rate, a 7.5 minute mile. Mucking up your long distance running plans even further, your body burns the highest percentage of fat at rest and it drops as the intensity of your exercise increases. So, as you pick up the pace, you are burning a smaller percentage from fat, increasing the number of calories you need to burn to drop a pound of fat if you are merely concerning yourself with calories in vs calories out. I would love to tell you this is the only problem with long distance running or chronic cardio, but it’s not. Actually, that’s a lie, I hate long distance running and the fact that it is unnecessary is why I don’t do it. You see, there has been a significant amount of research in this area for quite some time and all of it has shown that high intensity training outperforms long distance, low intensity training for fat loss as well as markers of carbohydrate and fat metabolism(4, 5, 6, 7)). The most telling study took place in 1994 by Tremblay, et al. This study showed that when matched calorie for calorie, high intensity interval training led to a 9x greater reduction in body fat than did running at a constant pace (7). How can that be, a calories is a calorie, right? While that is true, your body is not merely a machine that burns fuel, it’s quite a bit more complicated than that. In Part 2, we will go over the human machine in more detail.
Carbohydrates are the body’s preferred fuel source
This one is actually one of the easier myths to refute because the science it is based on is foolish. The reason given for carbohydrates being the body’s preferred fuel source is that they are metabolized first. The problem with this is they aren’t. If you put fats, proteins and carbohydrates in to the body the carbohydrates will convert to glucose which will be used first. If you add alcohol in to the mix alcohol is actually metabolized first, and I am going to go out on a limb here and say your doctor is not going to say alcohol is your body’s preferred fuel source.
If you recall from the calorie is a calorie section, alcohol aside, the energy sources from food actually have very specific attributes that lend themselves better to particular needs. Recall that glucose, the primary substrate from carbohydrate, provides a moderate amount of energy quickly while fatty acids from fat provide a lot of energy but at a slower rate. I suppose a good metaphor is that glucose is jet fuel while fatty acids are more like diesel fuel. For the most part, the obesity epidemic is primarily driven by people eating a jet fuel diet while living a diesel fuel lifestyle. Putting jet fuel in a diesel engine would cause the engine to run hot and blow out, in humans it tends to cause a hormonal response that leads to fat gain and, eventually, obesity. This is because the human machine has a few things that separate it from the engine. However, the running hot analogy does hold true for the human body as that is precisely what happens in Type 2 Diabetes.
Another case against carbohydrates being the preferred fuel source is our limited ability to store it. A well trained athlete can store approximately 500g of glycogen (The storage form of glucose), or 2000 calories. A 160lbs male with 15% body fat has 9,333g of stored energy as fat, which accounts for 84,000 calories. For glucose containing carbohydrate being the body’s preferred fuel source, we sure are lousy at storing it. Our glycogen stores are enough to power the body for about a day whereas you could run on your fat stores for weeks. Add to this the fact that excess carbohydrate will convert to fat while excess fat will only be stored as fat, and the grounds that “Carbohydrate is the body’s preferred fuel source” is on is shaky, at best.
Whole grains are good for you
Who on the planet has not heard the term heart-healthy whole grains? Few actually know this, but there are quite a few reasons why whole grains are not good for you. Since we are dealing with fat loss, we will not go over the fact that they bind nutrients and possibly prevent you from absorbing them(8, 9, 10, 11). We will also skip over the fact that grains contain storage proteins such as gluten that are a problem for a lot of people. For the purposes of this article we will only concern ourselves with the flawed research used to manipulate you in to thinking whole grains are healthy as well as their impact on energy.
Just to knock the research portion out of the park right away, 100% of the research showing whole grains to be healthy doesn’t actually show that. There have been 3 studies that I am aware of that directly compare whole grains to not eating grains at all, and the no grain group in each study had healthier outcomes (12, 13, 14). In addition, an older study showed complete remission of Type 2 Diabetes in a group of Australian aboriginals that reverted back to their traditional, grain-free hunter/gatherer diet (15). All of the studies that show whole grains to be “healthy” have compared them to refined grains, which we know are not healthy. So do those studies really show whole grains to be healthy, or do they just show them to be healthier than refined grains? Put another way, if I ran a study that showed crack to be healthier than heroin, would that study show crack to be healthy? I rest my case on that one.
Outside of the aforementioned issue with nutrient binding which is certainly not a trivial issue, whole grains are a large source of carbohydrate. Since these carbohydrates will eventually be broken down in to glucose, they will provide a quick source of energy. This is actually not a bad thing if you are someone who needs quick access to energy like a day laborer or an athlete, but if you are sitting on your rump all day long you are certainly not in need of quick access to energy.
Your doctor may have explained to you that the glucose from whole grains enters your bloodstream more slowly than, say, table sugar. What he or she may have failed to mention is that 2 slices of whole grain bread will eventually dump the equivalent of 5 teaspoons of table sugar in to your bloodstream. Add in a serving of pretzels and you are dealing with about 10 teaspoons of table sugar. Just for comparison’s sake, your entire blood volume holds just a hair under 1 teaspoon of glucose at a time. No matter how you swing it, that is a ton of fast acting energy that a sedentary person does not need so they are more than likely going to store it with the help of a hormone called insulin.
Humans are biologically driven to seek food and expend as little energy as possible to get it, and this is driven by hormones. Thanks to evolution via natural selection, a majority of us are engineered perfectly to eat as much as possible when the opportunity presents itself because it has been scarce for the vast majority of time. Insulin allows us to store fast acting energy for a time when we will need it, a fact most people know. From this point of view, we no longer need insulin for energy storage since we are in an environment where food is plentiful and there is no need to expend energy to get it. However, when you look at it from a blood glucose point of view, insulin is actually trying to pull glucose out of your bloodstream as fast as it can because high levels of blood glucose are very damaging to your blood vessels and organs. Our hormones make us ill-suited to our current environment.
In Part 2 we will examine how our metabolism works and things that we should be doing to keep it working properly.
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