6 ms·

And yet the article you're commenting on says that you don't burn more calories by exercising... If it is true, it definitely changes the narrative.

• ewindal 5y ago
  You’re reading that wrong. Of course you burn more calories through exercise. Michael Phelps couldn’t have eaten 12k cals a day if exercise didn’t burn calories.
  • __MatrixMan__ 5y ago
    Is it certain that we absorb all of the calories we consume? I went on a backpacking trip with my friends recently and despite similar activity levels everybody was surprised when they noticed that I eat twice as much as anybody else in the group. Maybe I should bring it up with a doctor, but I feel fine, I just also spend more on food than most.
    • stormbrew 5y ago
      Yes, this. These conversations about weight loss are so rife with spherical cows and people come to ridiculous generalizations because of it. Bodies are complicated and varied. "Michael Phelps eats 12kcal a day and yet he's not fat" is just a correlation, it doesn't mean anything. He's an extreme outlier of a person in many ways.
    • ajuc 5y ago
      I was eating similarly in my 20s and 30s and in 20s I kept about 80kg but in 30s I got to 130kg :/ BTW there are diseases that reduce calories absorbed, you might want to get checked for colitis ulcerosa and crohn's disease. They have nasty side effects so better to know earlier even if you don't have the worst symptoms.
    • Geee 5y ago
      No, there's lots of calories in stool, but it depends on the type of food. For example, eating lots of fats and oils tends to "go through". On the other hand, rate of metabolism varies between people too.
    • imtringued 5y ago
      The body absorbs refined carbs very quickly. The glucose rush will increase insulin levels to very high levels and make you feel hungry again soon leading to the consumption of even more calories.
  • csee 5y ago
    Well that's what the article says. The Hazda who walk 8-12 km a day burn the less calories as an average American (or the same after adjusting for body weight). Also that Phelps thing is highly questionable. He says he "probably" burns 8-10k, not 12k. Not the type of statement you want to rely on to dismiss all this work.
    • skohan 5y ago
      I just have a hard time believing it to be true that no amount of exercise will increase the overall caloric expenditure. For example, I've done a few multi-week bike tours, and we ate an enormous amount of mostly pasta every day, and managed to peel off a few pounds each by the end of it.
      • csee 5y ago
        The article mentions a study that tracked energy expenditure of runners over many weeks, and found that the energy expenditure was much lower at the tail end of the experiment, suggesting the body gets accustomed to the activity somehow and burns less energy.
        • ajuc 5y ago
          Well one obvious adaptation is losing fat = less energy needed to move the body.
          • csee 5y ago
            We saw a very large reduction in caloric expenditure in people who were already very fit runners. So body weight changes over the course of the experiment are unlikely to explain it.
            • magicalhippo 5y ago
              So if they just kept doing the experiment they would end up not needing to eat? Clearly there are some details that matter here...
  • tsimionescu 5y ago
    The article says pretty explicitly that, while you do burn more calories while exercising, your body finds other ways to compensate and generally keeps about the same total energy expenditure in a day. I'm pretty sure this doesn't apply to extreme cases like modern athletes, who explicitly push their bodies in many ways that normal fit people don't, and who have teams of doctors and coaches that can force them to keep up with exercise and diet even when their bodies are telling them to stop.
• ajuc 5y ago
  The article says you can't keep unhealthy diet and get fit just by exercising. Which is true in my experience as well - I was eating over 3000 kcal a day before I started counting calories, and if I haven't reduced that - no reasonable amount of exercise would have helped. What's tricky is that in early 20s I was eating about as much and it was fine.
  • nradov 5y ago
    There's a huge variation between individuals based on size, sex, and activity level. As a large, fairly active man I have to consume around 3100 kcal per day just to maintain body weight. But a small, sedentary woman might gain weight with even half that consumption. All else being equal, resting metabolic rate doesn't tend to slow down much as we age. The notion that people in their 20s can eat as they want without gaining weight is mostly a myth. It's more likely that you don't accurately remember what you consumed and your activity level in your early 20s.
• Elte 5y ago
  I'm a bit confused by this point in the article, because it also states: > There seems to be a hard limit on how many calories our bodies can burn per day, set by how fast we can digest food and turn it into energy. He calculates that the ceiling for an 85-kilogram man would be about 4650 calories per day. Given that "regular" people clearly do not burn 4650 calories per day, and it is possible to burn 4650 calories per day, there must be a point at which exercise _does_ increase energy expenditure. I'm guessing it just doesn't happen for regular doses of exercise (including, evidently, walking 14km per day). Perhaps the body down regulates calorie-consuming processes to a point where it's just the bare minimum, and calorie expenditure increases from there. Or perhaps we should take the opposite view and say that our bodies up regulate unwanted processes (like inflammation) to use the energy of an engine designed to keep running at a certain level? Either way I find this incredibly interesting. And either way I'm probably also going to keep stuffing my face on a day I run 30km :).
  • aixi 5y ago
    out of context, that quote is really funny; what happens once you reach 4650 calories? you start violating the rules of thermodynamics? (i know your body starts compensating for it and burning less calories, but still)
    • KronisLV 5y ago
      > what happens once you reach 4650 calories? Well, we probably need to look at the direct quote again. > There seems to be a hard limit on how many calories our bodies can burn per day, set by how fast we can digest food and turn it into energy. Maybe i'm reading this wrong, but if one's body were to burn calories at 100% of this supposed possible rate, then by the time you'd reach 4650, a new day would start. If digestion would top out at 4650 calories at day, with 24 hours per day, it would come down to 193.75 calories per hour. Or, in other words, it'd be about 3.23 calories per minute.
    • tempestn 5y ago
      Long term, yes. Short term you might be able to get some from fat stores. But the claim is that ~4650 is the most you can persistently get from food intake per day.
• tremon 5y ago
  Anecdotally, this has been my experience as well. I tend to think of my base metabolic rate as the integral over my physical activity over the last N years (it used to be N=5, but even that window is way too small I think now). Point being, you can be inactive for a long time without a meaningful change in body fat/weight, but eventually your body adjusts. Or rather, the first gain in body fat is offset by the loss of muscle weight. Once you're at a slower metabolic rate and less muscle, exercise becomes more difficult and it takes years of consistent activity to raise your metabolic rate again. I'm not sure how base metabolic rate relates to incidental energy expenditure. My gut feeling is that every body has its own limits on energy expenditure, and max TDEE doesn't need to correlate directly with base metabolic rate. That's why I mentioned the integral above. I tend to think of $TDEE_{max} \simeq MBR_{base} + E_{available}$ but $MBR_{base} \simeq \int_{t=-5}^0 TEE(t)$ -- and in my experience, weight loss correlates more with base metabolic rate than with caloric intake ($E_{available}$).