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I frequently see the following thermodynamic argument made when the topic of obesity comes up: If you want to lose weight, calories out must be > calories in.

• PragmaticPulp 5y ago
  > But it fails to appreciate the gigantic black box that is our metabolism. Metabolism isn’t really a black box. Millions of years of evolution have made us quite good at absorbing nutrients from food and using them conservatively. Our bodies won’t ignore ingested calories or burn excess calories for no good reason. If the body can absorb the nutrients, it will. If the body doesn’t have to burn calories to continue existing, it won’t. Evolutionarily, it wouldn’t make sense for our systems to evolve features that discard ingested calories or burn calories without good reason. Food wasn’t plentiful for the vast majority of our evolution. What actually happens is the person’s behavior changes: Many people adopt exercise programs but then eat more calories. Or they reduce caloric input but then spend more time resting. Or they cook smaller meals but eat more snacks and treats (which often go unreported in self-reported caloric intake studies) But there isn’t a condition where everything stays the same but the body suddenly decides it needs fewer calories to accomplish the same goals. That would imply the body has various degrees of inefficiency that can change over time, which isn’t really true.
  • ericmcer 5y ago
    This study deals with the more subtle aspects of calorie expenditure though. What if eating another 300 calories a day meant your immune system was stronger and you recovered more quickly and you felt more excited and energetic, but it had no effect on your weight?
  • BizarroLand 5y ago
    I think you're missing the insulin->carb cycle's effects, especially on people with metabolic syndrome issues. Carbs break down to sugars which trigger the release of insulin. However, cells can become insulin resistant to varying degrees, causing their muscles and organs to reject the free-floating sugars in the bloodstream. When that happens, your body fat gets to preferentially consume as much of the sugars as possible and then the kidneys filter out the excess. When this happens you end up with an undernourished body that doesn't process all of the calories in the food and that gains body fat preferentially to anything else. That body fat then becomes a hormone regulator, affecting mood and energy levels even further. There's so much that goes on in the body that isn't explained by calories in > calories out that, if not properly understood, can massively increase the difficulty of losing body-fat weight, (the body puts on fat over feeding its organs, the body doesn't get the nutrition it consumes to the cells that need it, the person is tired and eats too much to compensate, the list goes on I'm sure.) Recognizing that not becoming overweight in the first place is the ideal solution, but failing that ideal solution the follow up isn't as simple as "don't eat so much" is a better approach to take. Medical science has not cracked the code yet, but I'm willing to bet that someday soon we will find a solution that breaks this cycle, and when we do obesity and overeating will drastically reduce so that only the people with mental or emotional overeating issues will remain in the obese category.
    • PragmaticPulp 5y ago
      I was responding to the comment that metabolism is a “black box” that we can’t possibly understand, but metabolic syndrome is a good example of how we do understand metabolism including the exceptions. Metabolic syndrome is a severe exception, though. It’s not something that happens to average people eating normal amounts of calories. There are always exceptions in disease states, but those exceptions are invoked far too frequently in conversations about typical people on normal (not chronically hyper caloric or extremely sugar heavy) diets.
      • BizarroLand 5y ago
        Anecdotally, I have metabolic syndrome, which is part of the reason why I am so interested in the process and issues surrounding it. My body naturally burns about 15% fewer calories than it should all things considered, I would have to exercise for about 30 minutes every day to equal the same caloric burn as a twin of mine without the issue's sitting on their butt all day. Despite that, I've lost almost 100lbs from dieting (intermittent fasting, ECA stack, even Keto for a while) over the last several years but I'm still trapped by the condition as the less I weigh the worse the syndrome gets. Increased hunger, depression, lethargy, exhaustion, body temperature decreasing (painfully cold hands even in the middle of summer), insomnia, irritability, all of these issues hit me at the same time and get worse the lower my weight goes. I don't have diabetes, blood sugar and a1c are normal, no hypertension (actually hypotensive), generally decent health otherwise. Diabetes and excess fat isn't the disease, it's the visible symptom of a larger issue caused by the American diet and lifestyle. Sure, it's my fault (and my parent's fault) that I became obese as a child but now the typical solutions for the issue simply do not work, and people who refuse to see that there is more going on than simply "fat pigs won't stop eating" do literally less than nothing to help solve or identify the core issues. The food control / prevention of overeating solution works to prevent people from ending up like this, but rarely works to solve the issue once it has taken root, not to mention that the body typically doesn't lose fat cells once they have been created so even if you get to a normal weight you basically have a human fat cell parasite hungrily clawing at every morsel of food you eat more than what you immediately need permanently attached to your body unless you undergo surgeries to physically excise it from your body. (This is one of the reasons why most contestants on the Biggest Loser end up regaining their weight within a short amount of time, for instance. It's far easier to refill empty fat cells than it is for fat cells to be built by the body.) This is why obesity is a crisis. Not just because of diabetes, but because the tools that we have to fight obesity once it arrives are insufficient for the job.
  • matthewdgreen 5y ago
    >Evolutionarily, it wouldn’t make sense for our systems to evolve features that discard ingested calories or burn calories without good reason. Food wasn’t plentiful for the vast majority of our evolution. I don't understand the argument. I agree with you that the human body seems to have several mechanisms (in terms of behavior changes) for reducing food consumption and/or up-regulating calorie expenditure to avoid gaining excess weight. And presumably there were excellent evolutionary reasons for humans to evolve these mechanisms, even though food was often in short supply! (As someone who has spent time trying to do physical activity while overweight, I can attest to this.) But then you say that it wouldn't make sense for humans to evolve other physical mechanisms (such as changing digestion efficiency, fat storage efficiency) to accomplish those same well-motivated goals. Why not? I'm genuinely curious.
• eouiededuedu 5y ago
  You are correct. First, exercise. You cannot outrun your fork. Exercise is essential to your health, your longevity, your quality of life, and your weight. No one can lead a good life without regular, healthful exercise. Everyone should find some activity that they enjoy doing so that they are motivated to do it regularly. That said, hours of exercise calories can be eaten easily and mindlessly in moments. Bodies are evolved to survive in the wild and are very efficient. A handful of cookies can power you to walk for miles. So, second, diet. Different kinds of foods affect you in different ways. Food composition is important to your metabolism on both a molecular and cellular level. Molecularly, you need specific nutrients for health. But, additionally, food affects you based on its cellular form. So, eating whole broccoli is more taxing for your body to digest. The whole plant fibers act as food for commensal bacteria. Sugars packaged in intact cell walls are absorbed more slowly, and produce smaller hormonal responses in the body. The biggest problem everywhere are so-called highly-palatable foods. Candy, sweetbreads, soda, smoothies, white flour products, pop-tarts. These food-like substances come in what is effectively a partially digested state. Your body integrates their calories almost instantly. They feed festering bacteria rather than beneficial bacteria. Everywhere these foods are introduced, obesity is the result. Current nutritional research is woefully inadequate. The best studies, controlled environment studies, are heinously expensive and impossible over the course of years. Furthermore, the provision of funds for nutritional research is primarily done by biased, interested parties, so much of it is colored by funding sources. I invite you to examine the evidence presented by those such as Dr Greger: https://nutritionfacts.org/ https://nutritionfacts.org/ And I encourage you to look into this yourself.
• caturopath 5y ago
  A thermodynamic explanation doesn't explain everything as well as a lot of folks act like. The same thermodynamic laws apply to growing a tumor rather than growing a great fat mass. Our way of assessing food's caloric values are also imprecise. We act like all carbs and protein are 4kcal/g and all fat is 9kcal/g, but there is clearly some level of variation, some of it due to food and some due to individual. And of course we don't know for most ingredients how much of each macro and how much water they _actually_ have, we just use mostly-ancient reference values. All of that said, when we accurately track the amount of food people are eating, their weight does pretty predictably move with the calories in almost all circumstances. A lot of folks think they had other experiences, but people are really, really bad at accurately tracking their food intake. Shockingly bad, even when they're clearly trying. Similarly, when we measure people's oxygen usage, it tracks fairly predictably with weight changes, suggesting that we don't see outsized changes in 'metabolism' defeating folks. That still doesn't answer the question of why this is all happening.
  • diordiderot 5y ago
    There was a BBC documentary where a woman self reports eating 1000cal and tests reveal she'd eaten over 3000. https://m.youtube.com/watch?v=KA9AdlhB18o https://m.youtube.com/watch?v=KA9AdlhB18o
  • tsimionescu 5y ago
    > All of that said, when we accurately track the amount of food people are eating, their weight does pretty predictably move with the calories in almost all circumstances. This is only true in the short term - days,weeks. What is observed in the long term is that people, even the overweight and obese, reach stable weights without changing their lifestyle. So, if I were to start eating a surplus of 1000Cal/day compared to my current diet, and without changing my lifestyle in any other way, i would gain weight quickly until reaching some other significantly higher weight level, and then plateau there until I change other aspects of my lifestyle. This may be due in part to simple energy calculations (I need more energy to move around a higher mass), but is likely also affected by other metabolic factors as well (e.g. I would also develop stronger muscles to hold my bigger weight, and stronger muscles directly need more calories to be maintained). It's also extremely important, when discussing practical weight loss, to remember that appetite is also directly controlled by your body chemistry, and may vary wildly between people, probably explaining a huge amount of the observed weight differences.
• everdrive 5y ago
  I think the main problem is that many people simply say "I can't lose weight because of my metabolism." And this isn't true whatsoever. If instead they said "I lose weight at a slower rate than normal people because of my metabolism," or perhaps "cheat days have an inordinate effect on me because of my metabolism," I might be more sympathetic. The playing field is definitely not level, but weight remains calories in / calories out.
  • caturopath 5y ago
    Another charitable interpretation of a statement like that is, "When I eat so little food that I lose weight, I am not eating enough to nourish myself. I'm too hungry too much of the time, I have no energy, and I'm not even sure that I am getting what my body needs nutritionally."
    • adamisom 5y ago
      That’s a good point. Yet, if you’re an overweight male, you can probably both lose weight and get adequate nutrition on 2000 cals/day. For females the balance may be harder.
      • tsimionescu 5y ago
        Just a note - male vs female is almost irrelevant, the difference is almost entirely due to typical muscle mass differences.
      • caturopath 5y ago
        n.b., if you're a 5'9", slightly-overweight 50 year old man with an office job level of activity, you'll not be in a caloric deficit with 2000 Cal/day according to https://tdeecalculator.net/ https://tdeecalculator.net/ Actual nutrition -- getting the right micronutrients and such -- is the most questionable part of my interpretation, but it can still feel true to someone, they can still feel like their body just isn't getting what it's telling them it needs to feel right.
  • busyant 5y ago
• Blackthorn 5y ago
  Your body does an amazingly good job at extracting those calories. But you're still onto something else that varies with exercise, changes in diet, etc. It's called NEAT, which the article briefly mentions. It's why increasing your cardio won't linearly increase your fat loss. See a basic overview here: https://builtwithscience.com/non-exercise-activity-thermogenesis/ https://builtwithscience.com/non-exercise-activity-thermogen...
• deleted 5y ago
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• woopwoop 5y ago
  Why is that obviously true? There is not a 1:1 correspondence between calories and mass. There are more calories stores in a pound of fat than in a pound of protein. Why can't you lose weight while running a calorie surplus by losing muscle and gaining fat? This is an honest question. I've never understood this.
  • deleted 5y ago
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  • leephillips 5y ago
    People often say “weight” when they mean fat.
    • woopwoop 5y ago
      It's also not true that changes in body fat are proportional to calorie surplus.
      • leshow 5y ago
        What are you basing that on? There's a lot of other factors to consider... exercise and type of exercise, macronutrient breakdown, how large the surplus is, etc. edit: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786199/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786199/ have a look at this, it shows that hypercaloric diets will produce weight gain, and macronutrients have an effect on composition.
        • woopwoop 5y ago
          Why would changes in body fat be proportional to calorie surplus? Fat is not the only thing on the human body that stores energy. It is stored in proteins as well.
          • leshow 5y ago
            Fat is the main storage mechanism for surplus energy, not proteins. Proteins are relatively "expensive" to create and break down. Again, lot of other factors at play here, have a look at the linked paper.
• asdff 5y ago
  I think the average person doesn't realize just how little activity they do in a given day. The thermodynamics still apply, you just might be doing way too much sitting proportionally in a day and not nearly enough activity, and that has a far larger effect than any variance in metabolism. We evolved as persistent hunters who would walk down pray over miles a day, foragers who would range around the world chasing resources, now with work from home your range might be a few dozen feet within the confines of your home on an average given work day.
• Lammy 5y ago
  It also fails to appreciate the economic and emotional angles. Not only are do the cheapest ultra-processed foods tend to be the worst for you, but those foods are also designed to be as addictive as possible. Economic stress especially is omnipresent in modern society. Some people turn to drugs when life is stressful. Some people turn to food. Sometimes I wonder if there’s really that much of a difference. “Once you pop, you can’t stop”.
• leshow 5y ago
  How much of an effect can metabolism actually have though? That's the crucial part of this. If someone claims to be 300lbs and not losing weight eating say 1700 calories a day (made up numbers) I would just say they are either incorrectly calculating or not being truthful. By virtue of thermodynamics if they have a certain amount of tissue then they require a certain amount of base calories to maintain that tissue. Essentially, I think people misjudge how much of an effect metabolism plays compared to other factors, misreporting or miscalculating caloric intake, self deception, etc. Body composition is another thing entirely and involves going a layer deeper to macronutrient breakdowns and exercise variants.
• AndrewDucker 5y ago
  And, indeed, energy levels for the same food differs dramatically by person. https://www.sciencedaily.com/releases/2015/11/151119133230.htm https://www.sciencedaily.com/releases/2015/11/151119133230.h...