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Check this out - For years people have spoken of "slow metabolism" or "fast metabolism" as an explanation to why people’s “natural” body weights differ. I use the quote marks because I don’t believe in the concept of a natural body weight. But that’s another subject for another day. With regards to metabolism let’s look at what that word means and then we can establish if it's possible to boost it. (skip to the bottom if you want a quick summary but read on if you wanna know how I came to this conclusion).
It comes from the Greek word metabolē which means “to change” and the dictionary definition of metabolism is “the chemical processes that occur within a living organism in order to maintain life." But to simplify that, it means converting "potential" energy we consume from food and drink, into storable energy in our body that we can use to fuel the body.
A quick bit of science for you. The law of conservation of energy states that that "energy can neither be created nor destroyed; rather, it can only be transformed or transferred from one form to another."
In short ENERGY IN = ENERGY OUT
The two main forms of energy being, potential energy (stored energy), kinetic energy (movement energy). Within those categories are many different types but with regards to the human body we're talking mainly about chemical energy from food (the stored or potential energy) and movement or heat of the body (the kinetic/thermal energy).
Applied to the human body, this means that the energy (calories) we consume from food and drink, must either remain as potential energy (stored in the body) or converted to heat & movement energy. Alternatively we pass it as waste, so theoretically, the energy from food & drink we eat, gets converted first to either stored energy (fat & glycogen within the body) and this process is what we mean by metabolism. We "metabolise" the energy consumed from food & drink by changing it into stored energy within the body and when we consume more than we are using, it gets stored as fat.
So, "how do we use this energy?" I hear you cry. One way is movement! The more you move, the more you burn. And the heavier you are, the more you burn. That's why heavy people can lose weight more quickly than light people when on the same diet - because moving a heavier object requires more energy. Think about it. What would tire you out more? Pushing a push-chair or pushing a car? Same with bodies. Heavier bodies burn more fuel.
Inside our bodies we have many little movements and muscular contractions which will also burn fuel, such as peristalsis (the contractions of the intestines and blood vessels) and contractions of the heart lungs, diagram etc. But all of these are directly related to the amount of fuel we require to maintain temp or move. Move more, and you'll burn more.
Another way we burn fuel is to maintain our body temperature, which is usually around 37 degrees C or 98.6 degrees Fahrenheit. There are three main things affect how much energy we burn in order to maintain our body temperature. The first is the mass/size of our body. In the same way that heavier bodies require more energy to move, bigger/heavier bodies require more fuel to keep their temperature constant. Secondly, the difference between the temperature of your body and the ambient temperature around you will affect how much energy required to keep you warm. The colder it is the more energy you'll burn to keep warm. Thirdly, the more clothing or insulation you wear will affect how much energy you burn to maintain temperature. Walk around naked and you'll lose more heat and will need to burn more calories to maintain your body temperature.
So the amount of energy we burn is based on our bodyweight/size, amount of movement or activity we do, the amount of clothes we wear and the temperature around us.
Back to the original question...
Can we speed this process up? The process of converting food & drink into stored energy? Do we want to? What difference would it make if we convert the food into useable energy more quickly? Will it mean we burn more calories? No. 2000 calories of food and drink converted into 2000 calories of stored energy is still 2000 calories no matter how quickly you convert it. So why would a "fast metabolism" or "slow metabolism" make any difference to your weight? Personally, I don't see how it can. I know everyone says "fast metabolism" this and "fast metabolism" that, but sometimes you have to question what you've been told all your life and do your own homework.
In summary, I don't think we can't speed up metabolism per se, but why would we even want to? It doesn't mean we'll burn more calories or lose more weight. If anything it means we'll gain more weight because we'll be likely to process & store more of what we eat as body fat. That may have been a good thing millions of years ago when food was scarce and you didn't know when your next meal was gonna come along, but with Deliveroo and online shopping, food is always just a few minutes away.
So do as much physical work as you're prepared to do, and consume as many calories as you need in order to achieve this. And if weight gain is your goal, eat/drink more. And if weight loss is your goal, eat/drink less.
Next week I'll discuss the idea of digestion and how much of the energy we consume, do we actually "metabolise"? See you then!!