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"Beyond a certain point, your body senses the deficiency and decreases your metabolism. " As far as I'm able to tell this is a myth. There isn't any scientific

"Beyond a certain point, your body senses the deficiency and decreases your metabolism. " As far as I'm able to tell this is a myth. There isn't any scientific evidence supporting it, and quite a bit which implies it is impossible - if a body could run itself more efficiently then it would by default. Calorie consumption is necessary to sustain life. This myth is usually perpetuated by people who believe they are on calorie restricted diets, but who are actually eating more than they think.

guerrilla 4y ago
> This myth is usually perpetuated by people who believe they are on calorie restricted diets, but who are actually eating more than they think. Nonsense, the only places I've seen it are in popular scientific literature and in official recommendations, from dieticians and physical therapists. I don't know whether it's true or not, but my guess is you're probably wrong. The less someone eats, the more tired and weaker they feel, so they less they'd do, so the less energy they'd use. All kinds of feedback loops like that could happen. So it's definitely plausible.
- throwaway09223 4y ago
  "Popular" scientific literature, dieticians and physical therapists are demonstrably, profoundly unreliable sources. Besides, if you look around for opinions about the "starvation mode myth" you will find there is actually a lack of consensus. If you believe this is wrong then I suggest trying to articulate why you believe it is wrong, rather than appealing to cherry-picked non-authority opinions. The vast majority of calories our bodies burn are upkeep related and this upkeep does not change significantly based on our diet. Exercise is certainly a factor, but it is orthogonal to the question of whether our bodies somehow stop burning calories while continuing to operate itself. Most people in these extreme circumstances do not significantly exercise at all. Calorie restricted diets in a clinical setting where calorie inputs are strictly controlled will reduce weight 100% of the time.
  - dahfizz 4y ago
    > The vast majority of calories our bodies burn are upkeep related and this upkeep does not change significantly based on our diet. I don't think people really appreciate this. Running only burns about 100 calories per mile. So if you run 5 miles, you've only burned the calories you would get from eating one muffin. Many people will go for a walk around the block and feel like their getting into shape, but restricting calories is the only practical way to lose weight.
    - IIsi50MHz 4y ago
      Er, are we talking about same order of magnitude here? I notice that in USA, notably on food packaging, "Calories" (captalised) equals "thousand calories" (lower case). Elsewhere (including Japan), it seems that the kCals is used, avoiding confusion capitalisation.
      - goosedragons 4y ago
        Yes, a muffin is usually 300+ Calories or kCals and running a mile is ~100 Calories or kCals depending on your speed and weight. North Americans typically just use Calories for food and excerise contexts. Small c calories is really just used for science.
    - AlchemistCamp 4y ago
      > Running only burns about 100 calories per mile That’s only true for people who are both light and efficient runners. A better rule of thumb, at least for men, is 1kCal/hour for zone 2 or light zone 3 training.
      - dx034 4y ago
        If you like metric, a good approximation is also 1 calorie per kilometer and kilogram of body weight. So a 80kg person running a 10k will approx. burn 800 calories. Only an approximation but seems to roughly fit many "measurements" by smart watches for both males and females of different weight ranges.
ncallaway 4y ago
> if a body could run itself more efficiently then it would by default. Nobody suggested that the body "run itself more efficiently". They suggested that the body _do less_. This would be like if someone suggested that you could reduce gas consumption by not driving across the state, and for you to dismiss their argument as impossible because you just can't simply increase the MPG of the car. Of course, your statement is probably factually correct, but it's a non sequitur!
- throwaway09223 4y ago
  "Nobody suggested that the body "run itself more efficiently". They suggested that the body _do less_." This is another way of saying the exact same thing. Increased efficiency is doing less work. "Of course, your statement is probably factually correct, but it's a non sequitur! " It's a synonym! We are saying the same thing.
  - ncallaway 4y ago
    > This is another way of saying the exact same thing. Increased efficiency is doing less work. That's just not the definition of efficiency that I use. Efficiency is a ratio of how much _useful_ work something does over how much energy it consumes. If you change the numerator _and the denominator_ in the same proportions the efficiency doesn't change. Therefore, we cannot use "how much work changes" as a short-hand to speak to a chance in efficiency, _unless_ we also note how the denominator is or isn't changing. So, back to my analogy, the efficiency is the MPG and the "work" is the number of miles driven. Those are different things. You can reduce the number of miles you drive _without_ changing the MPG. > We are saying the same thing. From my definitions of words we are absolutely, categorically, not saying the same thing.
    - throwaway09223 4y ago
      I understand you use a different definition. Now that you know my definition there should be nothing more for us to discuss. Have a good one!
robonerd 4y ago
> people who believe they are on calorie restricted diets, but who are actually eating more than they think. Absolutely. For instance only counting the calories of their scheduled meals, but "snacks don't count because its just a snack". Or counting a heaping plateful of spaghetti as a single serving because they put it on a single plate. Underestimating calorie counts is much more common than estimating it accurately. Eat a few meals with a huge person who "just can't lose weight" and it will usually become obvious that they eat a huge amount of food.
- idontwantthis 4y ago
  I thought this too until I actually tried to lose weight. You measure everything you eat, and you lose weight for a week or so, and then you get tired, and irritable, and progress greatly slows down, stops, or reverses. Yes, some of it is willpower, and probably for lots of people it's entirely willpower, but there is definitely a metabolic component to it. If you eat less than you expend you must lose weight, but it's naive to discount a decrease in the expenditure part as well. Keep in mind that just living requires the vast majority of your calories, and any exercise is a blip covered by a couple cookies.
  - Hammershaft 4y ago
    Fasting makes the process easier.
    - deleted 4y ago
      [deleted]
  - what-the-grump 4y ago
    Cut your food intake by 50% and start drinking water / coffee to combat hunger. I know I am losing weight when I am hungry between meals, most of the time I eat because it’s time to eat. Down 10 pounds in two weeks. It’s nothing special just eating what I should be eating in terms of quantity. Eating sweets? Skip a meal, etc.
kenjackson 4y ago
I think you don’t much about how this works. The reason the body doesn’t just do this all the time is because when you lose weight in this mode your body begins to break down fat and eventually muscle. This is not a desired state for your body. These processes are far less efficient. And as noted in this article the body can reduce power in many ways to dampen the impact of these more inefficient and damaging processes. It’s advantageous to burn more calories when they are readily available.
- throwaway09223 4y ago
  These effects have been pretty well studied and while there are some small changes the body can make they are not significant. If you eat fewer calories you will lose fat. "when you lose weight in this mode your body begins to break down fat and eventually muscle. This is not a desired state for your body. " For the average american this is a highly desirable state. Almost all of us would be much healthier with a reduced calorie diet, with our bodies breaking down our excess fat. The effect of muscle loss is overstated. There are many obese and out of shape people who paradoxically point to "muscle loss" as a reason for not eating healthy, but people who actually understand muscle -- bodybuilders -- are very familiar with bulking and cutting cycles. This is a very well understood dynamic.
  - xboxnolifes 4y ago
    > For the average american this is a highly desirable state. Poster means from an evolutionary point of view, not a societal/modern individual point of view.
  - blindmute 4y ago
    Cutting yes, but note that cutting involves a very high protein diet in conjunction with continuing to lift weights. If a bodybuilder/powerlifter just stops eating and lifting, or even just stops eating, they will lose a large amount of muscle mass and/or strength along with the fat.
IggleSniggle 4y ago
I think the main issue is just that "efficient" can misleading to dieters. It's not efficiency as in "do more with less," but rather, "do less with less." As your body sheds fat, it no longer needs to expend energy building, preserving, and keeping your fatty tissue warm. JIT energy use instead of lossy battery storage. It doesn't further slow your metabolism beyond what you are genetically predisposed towards, but metabolism does slow (a little bit). Another way to think of this is, when you consume in excess of what you need for healthy living, your body begins consuming additional calories in order to build and support the additional long-term reserves you are creating and maintaining. We have decades of research supporting this notion (as well as common sense). There may also be an aspect of "hibernation" that kicks in when dramatic caloric restriction is suddenly introduced. That is, you are further inclined to be less active as you lose weight quickly. I'm less certain of that, though.
- rawoke083600 4y ago
  squinting hard enough there are some evolutionary mechanism at play, for example in times of famine(severe calorie restriction), menstruation will stop for female. Pretty sure sperm production also fall for men. So the body has definitely way to sense and adjust in some areas.
- rossnordby 4y ago
  "Do less with less" is a good way to put it. It can be helpful to look at the extremes- for example, people who are starving can end up with suppressed thyroid function (among other things). This appears to be adaptive; a hypothyroid state will tend to avoid building or sometimes even maintaining metabolically expensive muscle, overwhelming exhaustion will tend to suppress nonvital calorie expenditure, and even fidgeting behaviors can be suppressed. In other words, by reducing burn rate, you starve slower. This is not something you want happening in a well-nourished individual. Beyond making you more likely to die to predation or accidents from severe muscle wasting, it also just feels horrible. There's a reason why people with untreated hypothyroidism (unrelated to starvation) struggle with exercise and weight loss. I've also personally observed some people on... inadvisable extreme crash diets getting some weird bloodwork numbers. Like TSH spiking by a factor of 10- which, unlike the above starvation case which typically suppresses TSH, may imply malnutrition and inability to produce sufficient thyroid hormone. Their empirically derived caloric burn rate dropped by more than 30% over the duration of the diet, and a substantial amount of that was from dramatic muscle wasting. Not exactly ideal!
stakkur 4y ago
No, this is called homeostasis— the ‘set point’ or 'settling point' idea. Your body only sees weight loss as a threat to survival and tries to achieve a balance. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039924/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039924/
dataangel 4y ago
> if a body could run itself more efficiently then it would by default Don't suppose you see the article you're commenting on.
staticassertion 4y ago
I think the myth's origin is that if you start fasting/ really cut calories you'll notice a huge, immediate drop for a day or two - a lot of that being that you're losing water weight. Like going from a night of eating/ drinking, and then fasting the next day, I can see a 5 pound difference. Then that stops, and suddenly your scale isn't showing you the same drastic win as the first few days. You might reasonably think "I guess my body has adjusted". That isn't to say that your body doesn't change how it functions in order to save energy, obviously a lot changes when you've exhausted your glycogen stores. But I think a lot of the "drastic" results for people hitting a wall after a few days of fasting is based on that initial huge win.
scottlamb 4y ago
There was a recent discussion here about a nice article that went into this: https://physiqonomics.com/eating-too-much/ https://physiqonomics.com/eating-too-much/ https://news.ycombinator.com/item?id=31381410 https://news.ycombinator.com/item?id=31381410 I'll just quote the article: > The correct part: When you reduce calories, more specifically as you begin to get leaner, there is, in fact, some slowing of metabolic rate. > The incorrect part: Due to this low-calorie consumption your body decides fuck you and proceeds to enter this phantom zone of otherworldliness where the laws of thermodynamics cease to exist, resulting in no fat loss, or worse, gaining fat on some absurdly low number of calories. This 'low-power mode' seems consistent with the idea your metabolic rate can slow a bit. I read elsewhere that base metabolism varies between people by (iirc) ~15% even for a given weight/build due to genetics, weight training (as in its after effects, not the calories exerted during the workout itself), diet, etc. That's enough to be noticeable: 375 calories difference from a 2,500-calorie diet. It's not enough to back up "no matter how much I eat, I can't lose weight".
- dx034 4y ago
  The actual reason for many is probably that with a high enough deficit, you can feel so tired that it's hard to burn the same amount of calories. Walking 20k steps per day is no problem for most healthy adults, at such a deficit it becomes really hard.
  - scottlamb 4y ago
    > The actual reason for many is probably that with a high enough deficit, you can feel so tired that it's hard to burn the same amount of calories. Maybe, but for the folks most in need of weight loss, how active are they to begin with? Even for a fit person, it's often impractical to be active enough to make up for overeating. So while it'd be ideal to decrease intake without further decreasing activity, they'd still probably lose more weight by decreasing intake even if that brings activity to near-0. > Walking 20k steps per day is no problem for most healthy adults, at such a deficit it becomes really hard. Google Fit on my phone says I don't get 20k steps in, even though I run/jog four miles most mornings. I'm physically capable of moving more, but I have a full-time desk job, family responsibilities, etc.
andreareina 4y ago
Something very similar is claimed by Dr Mike Israetel. Specifically: after a prolonged period of a calorie deficit spontaneous activity (non-exercise active thermogenesis, NEAT) like walking around decreases, which accounts for a decent chunk of calories. On top of that the accumulated fatigue makes it difficult to train at high enough intensities to maximize muscle sparing. The end result is less weight loss, and less of that being fat. His recommendation is that fat loss phases are kept at 6-12 weeks with a few weeks of maintenance to dump both physical and psychological fatigue and to resensitize for the next day loss phase. So "decreased metabolism" is bunk, but as a model[1] it does a decent job of suggesting the correct action to take. Assuming calories are in fact under control: you're definitely right that a lot of people have essentially no idea how much they're eating. [1][eta: after enough time on a deficit, or just a great enough deficit, calorie expenditure spontaneously decreases without much recourse other than going back to calorie balance for a while]
plutonorm 4y ago
The article literally suggests the opposite? Are you a GPT-3?
danShumway 4y ago
> if a body could run itself more efficiently then it would by default TIL that underclocking is apparently not a real thing, and also that the results that the scientists are seeing in the linked study are impossible.
Cthulhu_ 4y ago
I don't have citations so this is entirely armchair, but, a few hundred kcal under your maintenance is fine for weight loss, going too far below that is a crash diet; going back or above your maintenance needs then will lead to your body storing extra, because it believes times are bad. One issue is that people go overboard with dieting, then any excess hits double. The other issue is that they go from one diet to the next, without ever establishing a stable baseline. You shouldn't try to lose weight if you don't even have a stable baseline yet.

guerrilla 4y ago

> This myth is usually perpetuated by people who believe they are on calorie restricted diets, but who are actually eating more than they think. Nonsense, the only places I've seen it are in popular scientific literature and in official recommendations, from dieticians and physical therapists. I don't know whether it's true or not, but my guess is you're probably wrong. The less someone eats, the more tired and weaker they feel, so they less they'd do, so the less energy they'd use. All kinds of feedback loops like that could happen. So it's definitely plausible.

throwaway09223 4y ago
"Popular" scientific literature, dieticians and physical therapists are demonstrably, profoundly unreliable sources. Besides, if you look around for opinions about the "starvation mode myth" you will find there is actually a lack of consensus. If you believe this is wrong then I suggest trying to articulate why you believe it is wrong, rather than appealing to cherry-picked non-authority opinions. The vast majority of calories our bodies burn are upkeep related and this upkeep does not change significantly based on our diet. Exercise is certainly a factor, but it is orthogonal to the question of whether our bodies somehow stop burning calories while continuing to operate itself. Most people in these extreme circumstances do not significantly exercise at all. Calorie restricted diets in a clinical setting where calorie inputs are strictly controlled will reduce weight 100% of the time.
- dahfizz 4y ago
  > The vast majority of calories our bodies burn are upkeep related and this upkeep does not change significantly based on our diet. I don't think people really appreciate this. Running only burns about 100 calories per mile. So if you run 5 miles, you've only burned the calories you would get from eating one muffin. Many people will go for a walk around the block and feel like their getting into shape, but restricting calories is the only practical way to lose weight.
  - IIsi50MHz 4y ago
    Er, are we talking about same order of magnitude here? I notice that in USA, notably on food packaging, "Calories" (captalised) equals "thousand calories" (lower case). Elsewhere (including Japan), it seems that the kCals is used, avoiding confusion capitalisation.
    - goosedragons 4y ago
      Yes, a muffin is usually 300+ Calories or kCals and running a mile is ~100 Calories or kCals depending on your speed and weight. North Americans typically just use Calories for food and excerise contexts. Small c calories is really just used for science.
  - AlchemistCamp 4y ago
    > Running only burns about 100 calories per mile That’s only true for people who are both light and efficient runners. A better rule of thumb, at least for men, is 1kCal/hour for zone 2 or light zone 3 training.
    - dx034 4y ago
      If you like metric, a good approximation is also 1 calorie per kilometer and kilogram of body weight. So a 80kg person running a 10k will approx. burn 800 calories. Only an approximation but seems to roughly fit many "measurements" by smart watches for both males and females of different weight ranges.

ncallaway 4y ago

> if a body could run itself more efficiently then it would by default. Nobody suggested that the body "run itself more efficiently". They suggested that the body _do less_. This would be like if someone suggested that you could reduce gas consumption by not driving across the state, and for you to dismiss their argument as impossible because you just can't simply increase the MPG of the car. Of course, your statement is probably factually correct, but it's a non sequitur!

throwaway09223 4y ago
"Nobody suggested that the body "run itself more efficiently". They suggested that the body _do less_." This is another way of saying the exact same thing. Increased efficiency is doing less work. "Of course, your statement is probably factually correct, but it's a non sequitur! " It's a synonym! We are saying the same thing.
- ncallaway 4y ago
  > This is another way of saying the exact same thing. Increased efficiency is doing less work. That's just not the definition of efficiency that I use. Efficiency is a ratio of how much _useful_ work something does over how much energy it consumes. If you change the numerator _and the denominator_ in the same proportions the efficiency doesn't change. Therefore, we cannot use "how much work changes" as a short-hand to speak to a chance in efficiency, _unless_ we also note how the denominator is or isn't changing. So, back to my analogy, the efficiency is the MPG and the "work" is the number of miles driven. Those are different things. You can reduce the number of miles you drive _without_ changing the MPG. > We are saying the same thing. From my definitions of words we are absolutely, categorically, not saying the same thing.
  - throwaway09223 4y ago
    I understand you use a different definition. Now that you know my definition there should be nothing more for us to discuss. Have a good one!

robonerd 4y ago

> people who believe they are on calorie restricted diets, but who are actually eating more than they think. Absolutely. For instance only counting the calories of their scheduled meals, but "snacks don't count because its just a snack". Or counting a heaping plateful of spaghetti as a single serving because they put it on a single plate. Underestimating calorie counts is much more common than estimating it accurately. Eat a few meals with a huge person who "just can't lose weight" and it will usually become obvious that they eat a huge amount of food.

idontwantthis 4y ago
I thought this too until I actually tried to lose weight. You measure everything you eat, and you lose weight for a week or so, and then you get tired, and irritable, and progress greatly slows down, stops, or reverses. Yes, some of it is willpower, and probably for lots of people it's entirely willpower, but there is definitely a metabolic component to it. If you eat less than you expend you must lose weight, but it's naive to discount a decrease in the expenditure part as well. Keep in mind that just living requires the vast majority of your calories, and any exercise is a blip covered by a couple cookies.
- Hammershaft 4y ago
  Fasting makes the process easier.
  - deleted 4y ago
    [deleted]
- what-the-grump 4y ago
  Cut your food intake by 50% and start drinking water / coffee to combat hunger. I know I am losing weight when I am hungry between meals, most of the time I eat because it’s time to eat. Down 10 pounds in two weeks. It’s nothing special just eating what I should be eating in terms of quantity. Eating sweets? Skip a meal, etc.

kenjackson 4y ago

I think you don’t much about how this works. The reason the body doesn’t just do this all the time is because when you lose weight in this mode your body begins to break down fat and eventually muscle. This is not a desired state for your body. These processes are far less efficient. And as noted in this article the body can reduce power in many ways to dampen the impact of these more inefficient and damaging processes. It’s advantageous to burn more calories when they are readily available.

throwaway09223 4y ago
These effects have been pretty well studied and while there are some small changes the body can make they are not significant. If you eat fewer calories you will lose fat. "when you lose weight in this mode your body begins to break down fat and eventually muscle. This is not a desired state for your body. " For the average american this is a highly desirable state. Almost all of us would be much healthier with a reduced calorie diet, with our bodies breaking down our excess fat. The effect of muscle loss is overstated. There are many obese and out of shape people who paradoxically point to "muscle loss" as a reason for not eating healthy, but people who actually understand muscle -- bodybuilders -- are very familiar with bulking and cutting cycles. This is a very well understood dynamic.
- xboxnolifes 4y ago
  > For the average american this is a highly desirable state. Poster means from an evolutionary point of view, not a societal/modern individual point of view.
- blindmute 4y ago
  Cutting yes, but note that cutting involves a very high protein diet in conjunction with continuing to lift weights. If a bodybuilder/powerlifter just stops eating and lifting, or even just stops eating, they will lose a large amount of muscle mass and/or strength along with the fat.

IggleSniggle 4y ago

I think the main issue is just that "efficient" can misleading to dieters. It's not efficiency as in "do more with less," but rather, "do less with less." As your body sheds fat, it no longer needs to expend energy building, preserving, and keeping your fatty tissue warm. JIT energy use instead of lossy battery storage. It doesn't further slow your metabolism beyond what you are genetically predisposed towards, but metabolism does slow (a little bit). Another way to think of this is, when you consume in excess of what you need for healthy living, your body begins consuming additional calories in order to build and support the additional long-term reserves you are creating and maintaining. We have decades of research supporting this notion (as well as common sense). There may also be an aspect of "hibernation" that kicks in when dramatic caloric restriction is suddenly introduced. That is, you are further inclined to be less active as you lose weight quickly. I'm less certain of that, though.

rawoke083600 4y ago
squinting hard enough there are some evolutionary mechanism at play, for example in times of famine(severe calorie restriction), menstruation will stop for female. Pretty sure sperm production also fall for men. So the body has definitely way to sense and adjust in some areas.
rossnordby 4y ago
"Do less with less" is a good way to put it. It can be helpful to look at the extremes- for example, people who are starving can end up with suppressed thyroid function (among other things). This appears to be adaptive; a hypothyroid state will tend to avoid building or sometimes even maintaining metabolically expensive muscle, overwhelming exhaustion will tend to suppress nonvital calorie expenditure, and even fidgeting behaviors can be suppressed. In other words, by reducing burn rate, you starve slower. This is not something you want happening in a well-nourished individual. Beyond making you more likely to die to predation or accidents from severe muscle wasting, it also just feels horrible. There's a reason why people with untreated hypothyroidism (unrelated to starvation) struggle with exercise and weight loss. I've also personally observed some people on... inadvisable extreme crash diets getting some weird bloodwork numbers. Like TSH spiking by a factor of 10- which, unlike the above starvation case which typically suppresses TSH, may imply malnutrition and inability to produce sufficient thyroid hormone. Their empirically derived caloric burn rate dropped by more than 30% over the duration of the diet, and a substantial amount of that was from dramatic muscle wasting. Not exactly ideal!

stakkur 4y ago

No, this is called homeostasis— the ‘set point’ or 'settling point' idea. Your body only sees weight loss as a threat to survival and tries to achieve a balance. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039924/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039924/

dataangel 4y ago

> if a body could run itself more efficiently then it would by default Don't suppose you see the article you're commenting on.

staticassertion 4y ago

I think the myth's origin is that if you start fasting/ really cut calories you'll notice a huge, immediate drop for a day or two - a lot of that being that you're losing water weight. Like going from a night of eating/ drinking, and then fasting the next day, I can see a 5 pound difference. Then that stops, and suddenly your scale isn't showing you the same drastic win as the first few days. You might reasonably think "I guess my body has adjusted". That isn't to say that your body doesn't change how it functions in order to save energy, obviously a lot changes when you've exhausted your glycogen stores. But I think a lot of the "drastic" results for people hitting a wall after a few days of fasting is based on that initial huge win.

scottlamb 4y ago

There was a recent discussion here about a nice article that went into this: https://physiqonomics.com/eating-too-much/ https://physiqonomics.com/eating-too-much/ https://news.ycombinator.com/item?id=31381410 https://news.ycombinator.com/item?id=31381410 I'll just quote the article: > The correct part: When you reduce calories, more specifically as you begin to get leaner, there is, in fact, some slowing of metabolic rate. > The incorrect part: Due to this low-calorie consumption your body decides fuck you and proceeds to enter this phantom zone of otherworldliness where the laws of thermodynamics cease to exist, resulting in no fat loss, or worse, gaining fat on some absurdly low number of calories. This 'low-power mode' seems consistent with the idea your metabolic rate can slow a bit. I read elsewhere that base metabolism varies between people by (iirc) ~15% even for a given weight/build due to genetics, weight training (as in its after effects, not the calories exerted during the workout itself), diet, etc. That's enough to be noticeable: 375 calories difference from a 2,500-calorie diet. It's not enough to back up "no matter how much I eat, I can't lose weight".

dx034 4y ago
The actual reason for many is probably that with a high enough deficit, you can feel so tired that it's hard to burn the same amount of calories. Walking 20k steps per day is no problem for most healthy adults, at such a deficit it becomes really hard.
- scottlamb 4y ago
  > The actual reason for many is probably that with a high enough deficit, you can feel so tired that it's hard to burn the same amount of calories. Maybe, but for the folks most in need of weight loss, how active are they to begin with? Even for a fit person, it's often impractical to be active enough to make up for overeating. So while it'd be ideal to decrease intake without further decreasing activity, they'd still probably lose more weight by decreasing intake even if that brings activity to near-0. > Walking 20k steps per day is no problem for most healthy adults, at such a deficit it becomes really hard. Google Fit on my phone says I don't get 20k steps in, even though I run/jog four miles most mornings. I'm physically capable of moving more, but I have a full-time desk job, family responsibilities, etc.

andreareina 4y ago

Something very similar is claimed by Dr Mike Israetel. Specifically: after a prolonged period of a calorie deficit spontaneous activity (non-exercise active thermogenesis, NEAT) like walking around decreases, which accounts for a decent chunk of calories. On top of that the accumulated fatigue makes it difficult to train at high enough intensities to maximize muscle sparing. The end result is less weight loss, and less of that being fat. His recommendation is that fat loss phases are kept at 6-12 weeks with a few weeks of maintenance to dump both physical and psychological fatigue and to resensitize for the next day loss phase. So "decreased metabolism" is bunk, but as a model[1] it does a decent job of suggesting the correct action to take. Assuming calories are in fact under control: you're definitely right that a lot of people have essentially no idea how much they're eating. [1][eta: after enough time on a deficit, or just a great enough deficit, calorie expenditure spontaneously decreases without much recourse other than going back to calorie balance for a while]

plutonorm 4y ago

The article literally suggests the opposite? Are you a GPT-3?

danShumway 4y ago

> if a body could run itself more efficiently then it would by default TIL that underclocking is apparently not a real thing, and also that the results that the scientists are seeing in the linked study are impossible.

Cthulhu_ 4y ago

I don't have citations so this is entirely armchair, but, a few hundred kcal under your maintenance is fine for weight loss, going too far below that is a crash diet; going back or above your maintenance needs then will lead to your body storing extra, because it believes times are bad. One issue is that people go overboard with dieting, then any excess hits double. The other issue is that they go from one diet to the next, without ever establishing a stable baseline. You shouldn't try to lose weight if you don't even have a stable baseline yet.