I have been slamming BigFood for convincing every one of us , with a bit of help from friendly researchers, that all calories are the same. I have been slamming the nutrition-ism in food, the reduction-ism of food science and the over simplification of the calories number game.
But, I haven’t been slamming everyone – my grandmother, our ancestors, – because I am convinced that they knew so much more, not because they fed mice in laboratories, but just from wisdom passed down from generations. They hardly experienced any food related chronic illnesses, or any lifestyle diseases because of their food habits.
It is impossible to figure out whom to believe with the hundreds and thousands of opinions related to diet and health. Is my slamming of the BigFood, and the modern concepts of nutrition, and the mumbo-jumbo of calories at all justified? Have I lost it?…you might ask.
I started upfront with the topic of ‘calories’ in my previous 3 (I think) posts because we are inundated with that word everyday. I had to set you thinking whether it is all that it is made out to be after all. At least you can ask the right questions to your gym instructor or your ‘eat less/move more’ advisors. In the next few posts, I’ll take a step back and talk about some funda issues about food so that you understand your body. You don’t need to believe me or anybody else nor get confused with the endless advises. When you understand the basics about how the human body really works, you will know why calorie counting, fat slashing, (yes , you read that right), and eating less/moving more is a one-way ticket to a black hole of frustration.
So let’s get cracking at what it is all about..
For the benefit of my friends who bunked the biology and physiology classes (me included, that’s why I had to catch up much later in life) I will just explain some simple fundas to understand what really is the role of food in our bodies. We talk about calories and carbs and proteins and fats and lipids and oils and hormones and enzymes and micronutrients and vitamins…and…and…and, but do we really know how all of this fits into the whole concept of our being. Why is food such an important part of our lives? Is it just for that tiny little burp which escapes our lips at the end of a satisfying meal or is there more to it? What does it really do ?
There are many theories on the origin of life. Whether God or Sheldon’s Big Bang (take your pick) created the first energy form on planet a few billion years ago, or, as some scientists believe, that in the beginning, there were simple organic chemicals. And they produced amino acids that eventually became the proteins necessary to create single cells. And the single cells became plants and animals. After billions of years, life on earth has evolved as we see it today. And humans have evolved to be one of the most complex, intricate multi-cellular organism if there ever was one. We have trillions of cells, each of which produce energy. We are a bundle of energy packed into skin and bones of varying shapes and sizes. Our whole existence is the energy we contain. We die because our cells die when they can no longer continue to generate energy. Life is energy.
Your ability to maintain a healthy body temperature, support your breathing, and a host of other functions to keep you alive, is called your basal metabolic rate, and you use more energy for these functions than for any other. Your body also uses energy to build new tissue, repair damaged tissue, and generate new, healthy cells. Even a simple eye movement requires energy.
Energy – our cells need to generate energy non-stop, 24/7, as long as we live. They need fuel to generate energy. This fuel comes from the food we eat. That is why we need to eat. So we see a broad level connection between food and our existence. It provides our body with stuff which keeps us alive. Cool! But why the fuss over carbs and fats and proteins and whatever….How do these different food types matter in the generation of life’s energy?
A beautiful red Lexus Hybrid. Our dear friends just bought this amazing car !! And I thought that if we are to talk about different fuel sources then this would be a great, though oversimplified analogy.
Think of the human body as a hybrid car. Just like a hybrid car, which can run on different types of fuel, depending on the situation, the human body can do the same. We can run on many different kinds of fuel, depending on how much of each type is available at any given time, and also depending on what kind of activity needs to be fuelled, which tissue type is performing the activity, and what messages our hormones are sending throughout our body regarding which fuels to use.
The main types of fuel the body can run on are:
For obvious reasons, we don’t want to fuel ourselves primarily on alcohol. A little hooch now and then is no problem (hic…), but we certainly don’t want it to be our main source of fuel.
Next up is protein. Even though protein is a source of energy, and therefore something we can consider as “fuel,” we really don’t want to use protein as our main energy source. It’s far too valuable for the myriad other purposes it has in our bodies. Besides contributing to the physical structure of muscle tissue, here’s just a small sampling of what else is made from protein: Antibodies, peptide hormones (like insulin and glucagon), neurotransmitters (like serotonin and dopamine), organs, and blood vessels. Protein has too many other jobs to do for it to be siphoned off as an energy source under normal circumstances. Sometimes amino acids from proteins are used for this as well, but only when your body doesn’t have enough of the carbohydrates and fats available. .
We’ll table ketones for the time being. They’re actually a fantastic source of fuel, but they deserve a much more detailed explanation than I can give here at the outset. We will talk about this alternative in later posts.
So that leaves us with carbohydrates and fat. These 2 sources of fuel are the most talked about by food scientists, nutritionists, dieticians, the media, doctors, laymen, everyone…..Let’s compare carbohydrate and fat as fuel sources and see if we can tease out which one it makes more physiological sense for us to run our bodies on.
As a general rule carbohydrates contain 4 kcal per gram; proteins are about the same; fats contain approximately 9 kcal per gram. In our analogy of a car, one fuel gives us say 4 km/liter and one gives us 9 km/l. So obviously if we use the 9km/l fuel we won’t run out of fuel so easily. Assuming that we use the 4km/l fuel, we would need to stop more often to fill up the tank as compared to the 9km/l. That’s obvious.
The thing about the human body is that we don’t just burn fuel. We don’t burn “calories,” and we don’t even burn carbohydrate, fat, protein, alcohol, or ketones. You see, the body can’t actually do anything with those macronutrients, per se. The human body can’t use carbohydrates or fats (or any of the other fuels) as they are. They have to be converted into something called ATP (adenosine triphosphate), —the “energy currency” of human physiology. Our cells can only use ATP. So we can think of pau bhaji, fish fry, steak, ice cream, chicken, eggplant, or even a well-aged Lagavulin and everything else we might toss down the hatch not as calories, or fuel, or energy, but as potential sources of ATP ( Why potential? – we will see that just because we ingest a food doesn’t mean that food is going to be converted into usable energy).
Mitochondria, you may remember it vaguely from your biology class, are present in nearly every cell in every organism in the world. It is the energy generating furnace in the cells. What we often call “burning” foods for energy, is really a process of breaking the molecules down piece by piece and transferring the energy that is released during this breakdown. The carbohydrate or fat is destroyed in the process. This breakdown of foods and transfer of energy in mitochondria requires oxygen, which you get from breathing, and results in carbon dioxide and water as waste products. The primary role of mitochondria is to produce ATP, which our body uses to create energy for a whole host of cellular processes. We are constantly using ATP, whether we’re sprinting, walking, breathing, pumping blood through our cardiovascular system, or doing long division. Think of a physiological process, and ATP is probably involved.Without mitochondria, then, we wouldn’t be able to get much of anything done. We simply wouldn’t exist.
Without going into the complex metabolic pathways involved in producing ATP from the food we consume, all that my non-nerdy friends need to know is that molecule for molecule, fatty acids provide way more ATP than carbohydrates do. My nerdy friends can check out the links below.
Energy Funda # 1: Gram for gram, molecule for molecule, fats give us more energy than carbohydrates. And not just “more,” but longer lasting, slower burning energy—the kind that can keep us feeling fine—physically, emotionally, and cognitively—for several hours without consuming more food, and without experiencing mood swings, irritability, immediate and urgent hunger, lightheadedness, dizziness, or any of the other unpleasant signs and symptoms of hypoglycemia, even if it’s been many hours since we last ate.
In some cases, our cells can also produce energy, in the absence of oxygen, from glycolysis, a fairly old biochemical pathway. This is done outside the mitochondria. It doesn’t require oxygen, which means it could have happened (and, in fact, was happening) way back when, in the very early days of life on Earth, like billions of years ago, when organisms were extremely simple, and the planet’s atmosphere was not oxygen-rich. Without a lot of oxygen in the atmosphere, it’s a good thing organisms had a way of generating energy that didn’t require any oxygen, right? And not only is glycolysis rather old, it’s also very inefficient. 2 ATP per one molecule of glucose. This anaerobic process is called fermentation. In spite of being so inefficient and primitive, this energy generating process is not all useless. For example, when oxygen levels are low, skeletal muscle cells rely on glycolysis to meet their intense energy requirements. This reliance on glycolysis results in the buildup of an intermediate known as lactic acid, which can cause a person’s muscles to feel as if they are “on fire.”
So now we know that some fuel lasts longer than the other. But what kind of fuel is the body designed to hold? If our hybrid car is designed to run on petrol and electric power, we will surely not tank it with diesel or orange juice!!
It’s the same with your body’s fuel tank. It is designed to store and use some fuels better than others.
I will reveal all in my ‘life is energy’ series. Stay tuned.