Sun, Oct-02-11, 09:55
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Plan: Muscle Centric
Stats: 238/153/160
BF:
Progress: 109%
Location: UK
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A Calorie Just a Calorie? No Way
An interesting post by Dr Berkley over at the Refuse to Regain blog:
Quote:
October 02, 2011
A Calorie Just a Calorie? No Way
by Barbara Berkeley, MD
A calorie is a calorie.
This is my least-favorite dietary mantra. Why? Because in the real world of real people and real weight loss, it isn’t true.
In scientific terms, a calorie is a specific measure that refers to the amount of heat needed to raise the termperature of 1 gram of water 1 degree centigrade. We can measure the amount of heat contained in any substance by burning it in a machine called a calorimeter. Using this narrow definition, there is no question that calories are all the same. One calorie of lettuce will raise 1 gram of water by one degree. So will one calorie of M&Ms.
But the colloquial usage of “a calorie is a calorie” (let’s call this C=C) bears no relation to the scientific definition. What's usually meant is this: diets that contain the same number of calories will have the same effect on your weight loss. It doesn’t matter if those calories come from chicken breast or chocolate cake.
Those who claim that any calorie we eat is equal to any other calorie, routinely invoke the First Law of Thermodynamics as evidence. This argument is a real show-stopper. It’s hard to argue with the basic laws of universe!
But a deeper look at the thermodynamic argument reveals many holes. The First Law says that energy cannot be created or lost, only transformed. C=C proponents interpret this to mean that any calorie that goes in has to be balanced by a calorie that goes out. If the balance is tipped one way or the other, you will either lose or gain weight. But the equation for the First Law was designed to represent energy in a closed system, not in a biological system that exchanges energy with the outside world. It would be much more true if the body acted like a perfectly consistent machine and burned all calories with equal efficiency. While all calories may be the same, the way in which the body burns calories is not. This variation depends on the package which surrounds those calories.
The calories in food don’t stand alone. They are intertwined with the other properties of foods… their protein, fat and carbohydrate contents for example. These properties have absolutely no effect on a calorimeter, but they have profound effects on the human body.
This leads to an important omission in the thermodynamic argument. While those who believe in C=C support their contention with the First Law of Thermodynamics, they never mention The Second Law. (There are four, but only two apply to the physics of food). This Law states that when energy goes through a transformation, there is always some loss of energy as heat. This dissipation of calories is a function of the efficiency with which the calories are burned.
In a 2004 paper on this topic Dr. Richard Feinman offered this useful analogy (the italics are mine):
The efficiency of a machine is dependent on how the machine works and, for a biochemical machine, the nature of the fuel and the processes enlisted by the organism. A simple example is the inefficiency of low-test gasoline in high compression gasoline engines. If a "calorie is a calorie" were true, nobody would pay extra for high test gasoline. (The calorimeter values of a gasoline will be the same whether or not it contains an antiknock compound).
This dovetails nicely with what I have observed clinically for many years; that our body loses fat, works better and is less hungry when we feed it “primary” or ancestral foods. I believe that these foods are our biological “high-test”. As I often say to first-time patients, “Your body is a Ferrari but for years you’ve been putting kerosene in the gas tank”.
Feinman’s article posits a “metabolic advantage” to low carbohydrate foods. There are many studies that show that at equal calorie levels low carbohydrate foods promote greater weight loss than high carbohydrate foods. While a single calorie of each of these foods will look exactly the same to a calorimeter, it doesn’t look the same to the body. One possible reason for the difference in weight loss? The brain needs a certain amount of glucose, or blood sugar, to run. On a low carbohydrate diet, the food we eat may not provide enough. The body has to manufacture its own sugar via a process called gluconeogenesis. This process uses energy and therefore burns calories. Thus, the net available energy from a low carb calorie is lowered simply by the fact that it provokes another, heat-generating, bodily process.
A low carb calorie may be very different from a higher carb calorie in other ways. It appears to suppress appetite better. A 2011 study in the journal Obesity reported that dieters who were fed a low carb diet for two years had significantly less hunger and a statistically significant decrease in cravings for sweets and starches when compared to those on a low fat diet.
A diet that is higher in protein may have the same calories as another diet, but the protein content may cause increased thermogenesis…the loss of calories that occurs through digestion. This effect and others are laid out in a paper in the Journal of the International Society of Sports Nutrition http://www.jissn.com/content/1/2/21.
And then there is this important consideration: many of us who eat the SAD (standard American diet) have developed insulin resistance. This is a condition in which insulin is produced in response to elevated blood sugar, but fails to work properly. The muscles, which normally would burn off some of this sugar, have stopped responding to insulin. Instead, there is diversion of calories into fat. For people with insulin resistance, calories from sugar and starch provoke a very different bodily response than do protein or fat calories. They should be avoided.
Perhaps the issue is not whether a calorie is a calorie. It is the understanding that a calorie is not ONLY a calorie. When it comes to food, the body reacts to myriad elements of the food package and calories may be only a minor part of that. Even for those who already believe that calories are just a single aspect of food, the answer to the question of perfect diet remains elusive. Much of the literature refuting the C=C position comes from scientists who support low carbohydrate diets. When designing studies that pit low carb against low fat diets, they tend to use the Atkins diet as the low carb choice. While I am firmly in the low carb camp I believe in low carb in the context of Primarian (or ancient-style) diet. In our clinic, we see all of the benefits of very-low carb diets like the Atkins induction (brisk weight loss, decreased hunger, correction of metabolic abnormalities). We achieve this, however, with Primarian plans which are less restrictive and easier to follow. Unfortunately, there are few studies that have looked at the effectiveness of ancient-style eating for weight and health.
The moral is this: calories are not the be-all and end-all we’ve been led to believe. While lowering calories is key to weight loss, the type of calorie you’re consuming is equally—if not more—important.
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