My brother, 21 yo, is like this. He’s ~180 cm tall and has never weighted more than 61 kg (during the 2020 covid lockdown, he made a big deal out of this since it was the first time he passed the 60 kg mark; after the lockdown was over he immediately dropped back to his perpetual weight of ~55kg). I live with him so I know his eating habits: he eats all the time, whatever he wants, whenever, how much he wants and simply doesn’t put on any weight. Is very energetic, no sick look / demeanour. It’s just fascinating to me cause I’m not like that at all, I have to watch what / how much / when I eat.

  • Opinionhaver@feddit.uk
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    22 hours ago

    The people “not gaining weight no matter how much they eat” often aren’t eating as much as you think. I’ve heard people say this of me too but they just don’t realise how often I skip meals. I regularly eat just breakfast and nothing else the entire day. Yeah, you might see me destroying 700 grams of candy at one sitting but what you don’t know is that’s also the only thing I’ve eaten all day.

    • shalafi@lemmy.world
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      19 hours ago

      I was the guy people used to think about like OP’s brother. When you see me hog down, it’s because I haven’t put a single calorie in my mouth up until then.

  • onebonestone@lemmy.world
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    1 day ago

    Genetics probably. Some people are suited for endurance sports, others gain muscle more easily. I recognize myself from the description. Very hard to gain muscle/weight and eating enough feels like a chore.

  • NABDad@lemmy.world
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    1 day ago

    Sometimes an actual medical condition makes the difference.

    At a yearly physical, my doctor noted, “no one could gain that much weight that fast without something wrong”. That’s how I got tested for and diagnosed with a thyroid disorder. It’s also the explanation for why I could never lose weight. I thought the reason I could hardly move was because I was just getting older.

    For years I had been unable to lose weight by dieting. After getting my thyroid levels corrected with medication, I became more active. I started casually intermittent fasting, and I lost 30 pounds.

    There’s also been research that shows your gut bacteria has a lot to do with whether you gain weight or not.

    https://www.uclahealth.org/news/article/gut-microbiome-makeup-can-determine-ability-to-lose-weight

    • hash@slrpnk.net
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      19 hours ago

      Which makes even more sense when you ask “where does the fat go?”

      Well where did that carbon you just exhaled come from?

  • FauxPseudo @lemmy.world
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    23 hours ago

    I was 61kg at 187cm from 15 to 30. I was eating 6000 calories a day to maintain that weight. Then I gained 22kg over the next three years and finally felt healthy for the first time. I had all the same health problems as anorexics while eating like an Olympic athlete.

    It was just genetics. Multiple family members were like this but not as bad as I had it. Now I have a nephew who has it just as bad as I did. He just has to wait another decade or so to achieve normalcy.

  • kernelle@0d.gs
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    1 day ago

    Is very energetic

    That’s the secret IMHO, being active is more than working out. Living an energetic lifestyle gives you a faster metabolism. Activate your core doing anything in your daily life will burn much more calories than slouching.

  • truthfultemporarily@feddit.org
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    1 day ago

    He eats less than he burns. Could be just high level of base activity - even just walking around a bunch makes a huge difference, much more than sports. Or could be very low appetite.

  • Ziggurat@fedia.io
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    22 hours ago

    As usual, weight is driven by Calorie in - Calorie out. If it’s positive you gain weight, if it’s negative you loose weigt.

    Your brother is a tall, young male, all of that would point toward a relatively high calorie out also without knowing him in details it’s hard to evaluate. There is always that person taking desert twice when out, but skipping lunch on regular day while doing a lot of sport.

    • Acamon@lemmy.world
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      20 hours ago

      Calories in - calories out is true, but people often have the wrong idea about it. It’s very much not ‘what you eat’ - ‘exercise’. Like you say, being a tall young man probably indicates a decent base calorie expenditure.

      Most people are aware that maintaining muscle mass spends more calories than maintaining fat stores (whose purpose is to provide calories during a famine!) but for many people the main uses of the calories they consume is to maintain body temperature. There’s indications that who are obese maintain a lower core temperatures during the day, which uses up less energy.

      How many calories are spent on maintaining body temperature varies between individuals by up to 600kcal. So it possible that you and I eat the exact same diet, and you go for a two hour walk every evening while I scroll my phone on the couch, and I’ll lose weight and you’ll gain it.

      And even in a sedentary lifestyle there’s a large variety of energy expenditure. Studies on esports are not conclusive yet, there’s some pretty dumb stuff sponsored by gaming companies that say shit like “one hour gaming = 1000 situps”. But more reputable studies suggest a more modest 50-100% increase in calorie expenditure compared to just sitting (so, the same as standing up or perhaps a gentle walk). And just fidgeting, changing posture and shifting in your seat can use up 350kcal

      So it’s perfectly possible for OP’s brother to not do much obvious activity, and still use up the equivalent of a couple of big macs or 7 cans of cola, compared with a less fidgety friend with a more ‘efficient’ metabolism.

    • amino@lemmy.blahaj.zone
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      22 hours ago

      this is actually misinformation that’s already been debunked. I recommend reading my other comment thread

      • HubertManne@moist.catsweat.com
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        18 hours ago

        yeah. when my metabolism was like this I was not sedentary but was not into sport. mosquitoes loved me (and still do) and they detect carbon dioxide so my bet is just more resting calorie burning or just an inneficient digestive system and maybe both.

  • Melvin_Ferd@lemmy.world
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    20 hours ago

    People burn calories at much different rates. Genetics, hormones, and medical conditions, NEAT all play big parts in this equation.

  • HubertManne@moist.catsweat.com
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    18 hours ago

    metabolism. I was like this in high school. it slowed down before 21 and continued to. This may happen to him but he is likely to keep a thin frame. If he does get fat it will likely be a pot belly.

  • Diplomjodler@lemmy.world
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    1 day ago

    Wait until he’s 30. I was pretty scrawny as a young lad. As soon as I turned thirty, I started putting on the pounds.

  • Mothra@mander.xyz
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    24 hours ago

    To chime in with the others and answer: hormones, activity levels, calorie intake. Those three give you your results. Hormones in particular will vary greatly and are influenced by activity levels but also by mental stress (or lack of), age, sex, environment variables such as temperature, etc.

    As to why you didn’t get that bingo card- nobody has an answer really.

      • Bestaa@lemmy.world
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        22 hours ago

        The linked page uses the Mifflin-St Jeor Formula which appears to have been published in 1990. As someone acquainted with eugenics but not how BMR calculations play a role, could you share some I formation on how the two are related?