Calorie Composition Matters
Monday, June 24, 2013
Calorie in minus calorie out is intuitive and simple: just move more, eat less. Except body composition it is not simple mathematics, but complex biochemistry. Note: this is ALL a lot more complicated, but some simplification is necessary. The problem is calorie is a calorie oversimplifies to the point where it's no longer valid. Yes, biochem majors, I am aware I am not telling the whole story.
So what is a calorie? "The amount of energy required to increase the temperature of 1 kilogram of water by 1 degree Kelvin."
A calorie is a measure of how much heat energy it generates. Human bodies are not machines. We don't burn fuel, turn it into heat energy, then spin wheels causing motion.
We consume energy, then transfer it to other molecules in our bodies. Some calories are burned for heat energy, but the vast majority are transferred into another form.
Food we eat builds or repairs cells, produces enzymes, or converts to stored energy. It can also be discarded in some situations.
The amino acids in protein are required for all of us. Animal proteins are the most readily available, and the energy transfer is very efficient. Protein in grains and cereals have very low efficiency - their amino acid composition for human needs is poor. The belief that overeating any calorie will lead to fat gain is sort of right, but there is a misunderstanding about why. It is not simply that the excess calories are shoved into fat cells. When we eat enough protein to meet our bodies' needs, the excess protein is either converted to glucose or discarded. We have no mechanism to store protein directly. Muscle building will only occur with the right exercise stimulus. Eating mountains of meat is wasteful and counter productive...unless you are exercising in a way that encourages muscle growth. (See my blog on the Man of Steel diet).
If you are a regular exerciser, fructose in small quantities is beneficial. It is converted in the liver to glycogen. Glycogen is burned when we exert ourselves during strenuous exercise. Unfortunately, due to modern food practices, almost every one of us over consumes fructose in processed foods. High levels of fructose cannot be processed in the liver fast enough, and is critically damaging to cells. Visceral fat comes mostly from excess fructose. Our liver only ever stores at most 100g of glycogen, and it is never, ever depleted. Even if we stopped eating completely, our bodies will continue to convert anything it can scavenge to glycogen. Muscle glycogen only comprises 1% of total muscle mass. A 20oz soda bottle contains 65g of sugar, and 35g are fructose. Modern hypersweet varieties of apples contain about 32.g of fructose. As you can see, it doesn't take much to over consume fructose - even if you aren't consuming junk.
Starches are a type of sugar. Table sugar is approximately 50/50 glucose and fructose. Starches are pure glucose chains. Fructose must be broken down in the liver, but glucose is ready immediately. This is great if you are a marathon runner or olympian, but it's not so good for the rest of us. High blood glucose is toxic, and the body must use or dispose of it immediately. If liver and muscle glycogen are topped off (which isn't much, as previously discussed), then our bodies try to find another place to put it. Our bodies stop burning fat to burn glucose. If energy burning needs are met, then where does the glucose go? It gets stored as fat. In a high glucose diet, energy needs are exceeded, so fat reserves aren't tapped.
What happens with fat is tricky. Fat in some scenarios becomes triglycerides. In others, they become ketones. Under normal circumstances, unneeded triglycerides (a type of fuel) should be removed by the liver, but there are a few ways this can get disrupted. In our modern diet, this is usually blocked by over consumption of glucose and fructose. When our bodies break down stored fat, they become ketones. However, as per the above paragraph, if there is already an abundance of glucose, fat burn doesn't happen the way we desire. Ketones are a byproduct of fat metabolism, and are either used or discarded, but they are not stored.
Consumption of calories that exceeds our expenditure needs can, indeed, lead to fat gain, but the mechanism isn't straight mathematics. Calorie composition DOES matter. Our bodies need enough protein, carbs and fat - all true. We all have to make our own decisions on what that is. If we have a lot of body fat to lose, it is most logical to reduce glucose consumption so that it stops impairing fat metabolism. Increasing exercise to burn more glucose seems like a good strategy, but then you aren't burning fat. This actually increases demand for protein. Lack of adequate protein and strenuous exercise leads to muscle catabolism.
I've achieved the most success with my weight loss journey when I juggle my food composition and exercise to get the result I want.