So I just went and donated blood again and durring the recovery period it occured to me that it takes quite a bit of work for your body to regenerate that lost blood volume and the actual blood cells. Regrowing that many cells seems like it would be fairly energetically intensive. So how many calories does producing all those new blood cells actually consume? Is there even a way to know that?

  • carl_dungeon@lemmy.world
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    1 year ago

    Oh man, instead of my daily workout, I could just donate daily! After a few months, I’d be a blood making machine!

  • fubo@lemmy.world
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    1 year ago

    The number floating around the web is 650 calories but I haven’t been able to track down the actual source.

    (Google Scholar is no help at all. Whoever these UCSD researchers are, I have no bloody clue.)

    • Overzeetop@kbin.social
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      1 year ago

      So I can shotgun two pints of beer after a donation (gotta rehydrate!) and still be a couple hundred calories ahead? Win-win!

    • Fosheze@lemmy.worldOP
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      1 year ago

      Hmm. Not as much as I hoped. You could probably eat that many calories in the free snacks they have afterwords without anyone even looking at you funny.

      • DrMango@lemmy.world
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        1 year ago

        There is no good way to outpace calorie consumption with activity. It is far far easier for humans to consume usable calories than it is for us to spend them.

        In our ancestors this meant that we were able to go a long time between good meals during times of scarcity and still survive, but today it just means that if you’re worried about calories you should start in the kitchen, not the gym

      • key@lemmy.keychat.org
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        1 year ago

        Eat the snacks before donating. That way your blood glucose spikes and you ‘burn’ maximum calories.

  • meseek #2982@lemmy.ca
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    1 year ago

    It’s something you’ll never truly figure out and can’t really as your body is a constant state of maintenance. When my brother was rushed to the hospital with pneumonia, the next day he didn’t really grow a beard. Makes sense. When you’re at deaths door, maybe don’t worry about growing hair.

    Your body is always managing resources.

    Basically it’s going to take the energy needed from other maintenance items (hair, nails, skin, etc.) and devote them to blood manufacturing. It’s also going to cut your energy to save calories so you’ll feel pretty sluggish for a bit.

    How we currently deal with calories is just wildly misleading.

    • HappySquid@feddit.ch
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      1 year ago

      Yeah. “Calories in calories out” is correct in theory but it is an oversimplification. Most people burn a vastly majority of their calories “at rest” by just maintaining their body temperature.

    • DrMango@lemmy.world
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      1 year ago

      Considering a day’s worth of calories varies by person and that the general recommendation is 2,000 calories per day for an average, active adult I would question this idea

      • HeyThisIsntTheYMCA@lemmy.world
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        1 year ago

        We have 10-ish units of blood in our body. When we donate we give one unit. A unit is around 500ml. Someone else on the thread says 650 cal per donation. That means each ml of blood takes 1.3 calories to make. Work harder you lazy bastards! I didn’t make you out of butter to pump like this!

      • Ejh3k@midwest.social
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        1 year ago

        Then wouldn’t it make sense to not put an actual figure down for how much donating is actually freeing up?