What is “metabolism” exactly?

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  • myszka0611
    myszka0611 Posts: 17 Member
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    TimothyFish wrote: »
    What many people on weight loss forums are actually asking is "What can I do so I can eat more without having to exercise?" Telling these people what it takes for a more efficient metabolism doesn't really answer their question because a more efficient metabolism means that we require less food to do the same amount of effort.
    I don't particularly "want to eat more without having to exercise", I was simply asking what mechanism in the body...this amorphous "metabolism"... creates, IMHO, a contradiction. Why it seems to be at odds with what is best for the body it is supposed to be working to protect. I have to consciously fight my urge to eat more. One part of "me" says "eat more!!!" Another part of "me" says, "You're eating too much! Just for that, I'll make this nice plop of fat for you right here on your belly.".

    This was my line of thinking in my original query...not necessarily "how to circumvent my metabolism", but just "what the heck is a metabolism in the first place?" Why does my "metabolism" cause me to crave more than my body needs? I wondered what constitutes a "metabolism"? What makes it work/not work? How to fine tune it?

    (You guys have since provided a plethora of great responses! Thanks for that!)
  • TimothyFish
    TimothyFish Posts: 4,925 Member
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    myszka0611 wrote: »
    TimothyFish wrote: »
    What many people on weight loss forums are actually asking is "What can I do so I can eat more without having to exercise?" Telling these people what it takes for a more efficient metabolism doesn't really answer their question because a more efficient metabolism means that we require less food to do the same amount of effort.
    I don't particularly "want to eat more without having to exercise", I was simply asking what mechanism in the body...this amorphous "metabolism"... creates, IMHO, a contradiction. Why it seems to be at odds with what is best for the body it is supposed to be working to protect. I have to consciously fight my urge to eat more. One part of "me" says "eat more!!!" Another part of "me" says, "You're eating too much! Just for that, I'll make this nice plop of fat for you right here on your belly.".

    This was my line of thinking in my original query...not necessarily "how to circumvent my metabolism", but just "what the heck is a metabolism in the first place?" Why does my "metabolism" cause me to crave more than my body needs? I wondered what constitutes a "metabolism"? What makes it work/not work? How to fine tune it?

    (You guys have since provided a plethora of great responses! Thanks for that!)

    We tend to think about "best" in terms of how fat we are. We should instead think in terms of what we need to fuel our bodies. We know about how long it will be before we can eat again. Our bodies don't. As intelligent beings we can and should either decide to eat less than we can now because we'll be eating again in a few hours or maybe we should decide to eat more because we know we are going to be burning more calories than normal between meals. All our bodies can do is react to the current situation. It would be a bad thing if we ate more in preparation for going for a few days without food and our bodies refused to store the food.
  • CattOfTheGarage
    CattOfTheGarage Posts: 2,750 Member
    edited March 2017
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    fbchick51 wrote: »
    CattOfTheGarage wrote: »
    I have to pull you up on this. Eating a healthy diet does not mean there is more energy available - if it does, it will make you fat. The amount of energy in food is the amount of calories, and that is completely different from the feeling of being energetic. Being energetic is a measure of how keen your body is to spend energy. It's not a measure of how much energy it has available. If it were, fat people would never get tired.

    And you never escape from "simple CICO".Cars, ships, stars, planets, they're all governed by energy conservation, it's the closest thing to an absolute in this crazy quantum universe. The CI and CO can change but the CICO never goes away.

    Maybe I should have used the term "readily available"... meaning that instead of the calories being stored in fat cells, it's actually processed and pushed to the places that need and want to use it. I'm talking about the difference between two people.. one who eats 2000 calories of low nutrient dense, high simple sugars foods versus the 2000 calorie diet rich in nutrient dense foods made up of proteins, complex carbs and healthier fats. While CICO is that basic formula, our bodies are actually more complex then that. So when asking questions about how to change ones metabolism, you must dive deeper then the simple CICO.


    But "readily available" energy is the opposite of what you mean.

    Glycaemic index is a direct measure of how readily available the energy in food is. High glycaemic index foods, like sugar, syrup, white bread, have lots of readily available energy which goes straight into the bloodstream and is immediately present in all parts of the body that need energy. Low glycaemic index foods like fruit and whole grains contain energy that is not readily available and takes time and effort to extract. The effect in terms of how good and bright and bouncy you feel is the opposite of what you are suggesting.

    You're conflating actual energy with the feeling of wanting to be active. The two things are not the same at all and are not even related in a simple way.

    (Also, saying that to alter metabolism you have to go "deeper than simple CICO" is at bit like saying that to understand an aircraft you need to ignore gravity.)
  • earthnut
    earthnut Posts: 216 Member
    edited March 2017
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    myszka0611 wrote: »
    Why, if I eat too little, does my metabolism slow down? Why then, in the reverse scenario, doesn’t it speed up if I eat too much?
    Because, for the vast majority of human history, the most important thing was to prevent you from starving to death when food became scarce. Food availability wasn't reliable, as it is today in our culture. The body reacts to dieting like you are at risk for starving. The best thing for your survival is to be able to survive the worse case scenario. So if your body thinks food is scarce, it will make your metabolism slow down and become efficient at using what little food you have. When calories increase, your body doesn't respond right away because it wants to protect you against that food shortage happening again. It will stay efficient for a while so that you store fat. The stored fat will protect you against future food shortages.

    Eventually, if you maintain your weight loss, your metabolism does go back to normal. If things are stable, your body eventually stops freaking out. For some people this takes months, for others it takes years. You can't really speed up metabolism past it's "normal" point. And I don't know of a way to hasten going back to normal either. "Normal" is genetically determined.

    The slowing down of the metabolism in response to food shortages is called "adaptive thermogenesis". There are a few things your can do to PREVENT this while losing weight. One is to maintain your lean body mass (namely muscle). You can do this by eating sufficient protein and lifting weights. The other is to lose weight slowly and take diet breaks. This tricks your body into thinking that there is no real food shortage, or at least not one that is lasting for long and is of any danger.
  • crackpotbaby
    crackpotbaby Posts: 1,297 Member
    edited March 2017
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    For the most part you thyroid gland and associated hormones regulate your metabolism.

    The thryroid gets feedback from the hypothalamus in your brain and from the pituitary gland in your brain.

    For example a fever (caused by a negative feedback loop in the hypothalamus) can cause metabolic rate to increase.

    There are lots of other things that give feedback to these areas of the brain and endocrine system that in turn have impact on metabolic rate, which changes throughout the day and under different conditions.

    A good place to get a grasp on this would be to look at a university level anatomy and psysiology text book. There is probably one in your local library.

    addit: the hormones and habits that trigger hunger cues are not necessarily linked to those that control metabolism.

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