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> The point is there are people that are eating large fries and triple thick milkshakes as snacks driving from place to place because it makes them feel happy i

> The point is there are people that are eating large fries and triple thick milkshakes as snacks driving from place to place because it makes them feel happy instead of just eating to feel full. And you just can't outrun that. You literally can. You just need to burn more calories than you take in. It would be difficult but not impossible and is simple math and thermodynamics.

ehnto 1y ago
The thermodynamics argument misses the fact that our body is not a single input, output engine. The body will use energy from several different sources, with different efficiencies. It will store energy in different forms, with different efficiencies, and it throws away a lot of energy that you put into it. Yes, if you spend energy, it has to come from somewhere, but it's only in really specific scenarios that it comes from fat. No one is measuring how much they actually burn either, so we are all just theory crafting that someone burnt X and put in Y so they should be losing fat stores. Maybe they burned Y from blood sugar, super efficient, before it was stored into fat, great. Or maybe they stored it as fat overnight, and they are burning 98% of their breakfast from bloodsugar and only 2% from fat stores. Some people's bodies will have them completely tired out before they even hit their fat, that's a lack of fitness not a caloric deficit. In general yeah, thermodynamics wins, but the details do matter.
- weird-eye-issue 1y ago
  You are completely wrong because over the long term, thermodynamics isn’t just a theory — it’s the governing principle. No matter how “inefficient” the body is at using or storing energy, it still obeys conservation of energy. If you consistently burn more calories than you consume, your body has to draw on stored energy (fat, muscle, glycogen, etc.) to make up the difference. That’s not up for debate — it’s been proven across thousands of controlled metabolic studies. Yes, the short-term details can vary — sometimes you’re burning glycogen, sometimes fat — but over weeks and months, a sustained calorie deficit always results in weight loss. The body doesn’t magically create energy out of thin air because its “efficiency” fluctuates. You can argue that diet composition and hormones affect how easy it is to maintain that deficit, but not the fundamental physics behind it. So while you’re right that biology is messy in the short term, thermodynamics still wins every single time when you zoom out. It doesn't matter what source you are burning your energy from at any given time for long term weight. Let's say you eat a bunch of carbs and then you go for a run, well you're probably going to burn those carbs off first (depending on how hard you run and other factors). Which according to you doesn't matter since it's not burning stored fat. But if you didn't go for that run then those carbs would turn into fat later.... And if you go for a really long run (or you take it easier) then you will start burning the stored fat. But either way it doesn't actually matter because calories in / calories out still is the determining factor.
  - lucyjojo 1y ago
    you are completely ignoring injuries, deficiencies and genetic particularities. the human body is not a linear system. it's markedly self-regulated and non-linear, and things can get pretty bad pretty quick.
    - weird-eye-issue 1y ago
      None of that changes anything that I said
  - ehnto 1y ago
    In the same way that we don't rely on the assurance of entropy to mix stew however, thermodynamics is not something to base your diet and exercise plan on. We both know you are technically correct, but it doesn't help you to plan your lifestyle change to know it. That's why it's a frustrating reduction of the problem, the knowledge inbetween helps us make good decisions that involve a lot more than just the physics of the problem. For someone I know gets it I can just say "eat less than you move" and that is the whole fitness plan, makes sense, but that's because they are filling in all the details for me. When to eat, what to eat, how much to eat, how much and when to move etc etc.
    - weird-eye-issue 1y ago
      Of course details matter when you actually implement it in your life But there are people arguing about the underlying concept of calories in/out being wrong which is just silly > thermodynamics is not something to base your diet and exercise plan on Except it literally is. You can use it to figure out exactly how much weight you'll gain/lose over the long term if you track things properly
      - ehnto 1y ago
        I was not doing that. I was pointing out how reducing the problem to thermodynamics is not a particularly helpful part of the conversation. I see it a lot, it's not a novel insight but it is often unhelpful.

ehnto 1y ago

The thermodynamics argument misses the fact that our body is not a single input, output engine. The body will use energy from several different sources, with different efficiencies. It will store energy in different forms, with different efficiencies, and it throws away a lot of energy that you put into it. Yes, if you spend energy, it has to come from somewhere, but it's only in really specific scenarios that it comes from fat. No one is measuring how much they actually burn either, so we are all just theory crafting that someone burnt X and put in Y so they should be losing fat stores. Maybe they burned Y from blood sugar, super efficient, before it was stored into fat, great. Or maybe they stored it as fat overnight, and they are burning 98% of their breakfast from bloodsugar and only 2% from fat stores. Some people's bodies will have them completely tired out before they even hit their fat, that's a lack of fitness not a caloric deficit. In general yeah, thermodynamics wins, but the details do matter.

weird-eye-issue 1y ago
You are completely wrong because over the long term, thermodynamics isn’t just a theory — it’s the governing principle. No matter how “inefficient” the body is at using or storing energy, it still obeys conservation of energy. If you consistently burn more calories than you consume, your body has to draw on stored energy (fat, muscle, glycogen, etc.) to make up the difference. That’s not up for debate — it’s been proven across thousands of controlled metabolic studies. Yes, the short-term details can vary — sometimes you’re burning glycogen, sometimes fat — but over weeks and months, a sustained calorie deficit always results in weight loss. The body doesn’t magically create energy out of thin air because its “efficiency” fluctuates. You can argue that diet composition and hormones affect how easy it is to maintain that deficit, but not the fundamental physics behind it. So while you’re right that biology is messy in the short term, thermodynamics still wins every single time when you zoom out. It doesn't matter what source you are burning your energy from at any given time for long term weight. Let's say you eat a bunch of carbs and then you go for a run, well you're probably going to burn those carbs off first (depending on how hard you run and other factors). Which according to you doesn't matter since it's not burning stored fat. But if you didn't go for that run then those carbs would turn into fat later.... And if you go for a really long run (or you take it easier) then you will start burning the stored fat. But either way it doesn't actually matter because calories in / calories out still is the determining factor.
- lucyjojo 1y ago
  you are completely ignoring injuries, deficiencies and genetic particularities. the human body is not a linear system. it's markedly self-regulated and non-linear, and things can get pretty bad pretty quick.
  - weird-eye-issue 1y ago
    None of that changes anything that I said
- ehnto 1y ago
  In the same way that we don't rely on the assurance of entropy to mix stew however, thermodynamics is not something to base your diet and exercise plan on. We both know you are technically correct, but it doesn't help you to plan your lifestyle change to know it. That's why it's a frustrating reduction of the problem, the knowledge inbetween helps us make good decisions that involve a lot more than just the physics of the problem. For someone I know gets it I can just say "eat less than you move" and that is the whole fitness plan, makes sense, but that's because they are filling in all the details for me. When to eat, what to eat, how much to eat, how much and when to move etc etc.
  - weird-eye-issue 1y ago
    Of course details matter when you actually implement it in your life But there are people arguing about the underlying concept of calories in/out being wrong which is just silly > thermodynamics is not something to base your diet and exercise plan on Except it literally is. You can use it to figure out exactly how much weight you'll gain/lose over the long term if you track things properly
    - ehnto 1y ago
      I was not doing that. I was pointing out how reducing the problem to thermodynamics is not a particularly helpful part of the conversation. I see it a lot, it's not a novel insight but it is often unhelpful.