• Platypus@sh.itjust.works
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    3 days ago

    there’s enough energy in a sugar cube to power my home for months

    …what? If that were close to true we’d be burning sugar instead of coal

    • Fleur_@aussie.zone
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      3 days ago

      No no no you see some people have the E=mc^2 gene which lets them metabolise mass directly into energy and so scientifically can never be held accountable for their weight.

      • Valmond@lemmy.dbzer0.com
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        3 days ago

        I know you’re sort of joking, but metabolism is extremely badly understood (most is not understood at all), and different people extract different amounts of ATP from food than others, that’s just a verifiable fact. And eating less will make you lose weight, but how much less depends on, you guessed it, metabolism… So just saying “eat less” isn’t very helpful IMO.

        And it has not really anything close to do with thermodynamic laws, or you Had to have the emc2-gene for it to matter, thats all.

        It’s like relativity physics and car driving, it does intersect, but really not in any meaningful way.

        • Fleur_@aussie.zone
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          3 days ago

          My point is people get too hung up on “how much less depends on, you guessed it, metabolism… So just saying “eat less” isn’t very helpful IMO.” That they forget “And eating less will make you lose weight”

          That’s my whole point. You gotta eat less if you want to lose weight and you can dig around in the science and semantics of it all you want but the bottom line doesn’t change.

          • Valmond@lemmy.dbzer0.com
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            3 days ago

            Sure, but it’s not like people don’t know that, right? My take is sport, ditching sugar and so on will help you to eat less. Another thing is that the body reacts differently when you eat fat and sugar at the same time versus eating sugars, then later eating the fat. You are not wrong but there are many ways to get to the “eat less” IMO.

    • ricecake@sh.itjust.works
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      3 days ago

      Nope, there’s just even more energy in a lump of coal.
      I believe their point is that it’s a bit silly to sit around focusing too much in thermodynamics beyond the raw limits, when there’s a lot of factors that weigh in to how much of the theoretical maximum is available or used. Beyond just the basic chemistry involved, there’s hormones that influence how it’s used, and peoples urges to consume.

      • Platypus@sh.itjust.works
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        3 days ago

        That’s just not true.

        The average home in the US uses 10,000 kWH per year; let’s be generous and call that 500 kWH per month, or 2e9J.

        A sugar cube is 5g. To power a home for a month, it would therefore need a specific energy of 2e9J/5g = 0.4e9 J/g. Normally specific energy is given in MJ/kg, so we get a minimum needed of 400,000 MJ/kg.

        Coal, per Wikipedia, comes in at 26-33 MJ/kg. Liquid hydrogen gets over 140, and that’s the most efficient fuel on the list.

        I didn’t bother to look up the specific energy of sugar, but somehow I doubt it laps coal by orders of magnitude. The only possible way it could have that much energy is if we could convert its mass directly to energy, but neither technology nor biology can do that right now so it’s a bit silly to even mention.

        • ricecake@sh.itjust.works
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          2 days ago

          neither technology nor biology can do that right now

          Yes, that was the point. If we focus purely on the math to the exclusion of reality you get results that don’t apply to reality.

          If you only look at thermodynamics when discussing weight loss you get the best possible weight loss advice: “eat less”.
          It happens to ignore the reality of biology, how the body reacts to changing nutrition, or how it reacts towards changing your desires when nutrition changes, but it is technically correct.

          Just like it’s technically correct to say that a sugar cube has enough energy to power your home for a long time. It may be a useless observation, but it’s technically true.