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.
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.
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.
Often on prolonged diets, your NEAT can unconsciously decrease from a series of small decisions like choosing to take the elevator when you usually take the stairs, parking nearer to your destination, etc. and even things like fidgeting less.
You can kinda get around this with things like step counters so you can track how many steps per day you normally walk, and then if you notice you're suddenly walking fewer steps, you can consciously choose to walk more to keep your activity level at your baseline.
For example, you might average 8,000 steps per day but after a few months on a diet, you find yourself walking 4,000 steps per day naturally so you can just choose to go out for a walk after dinner to maintain or increase your baseline level of activity.
When people talk about changes in metabolism, this is normally the culprit.
You’re not losing a meaningful amount of fat in the first week. You’re just getting dehydrated.
I’ve seen this process up close multiple times. It usually starts with a dramatic weight loss goal like “I’m going to lose 2kg/week for a month.” The first few days of crash dieting seem to be working, then the rapid progress stops and it becomes clear that the original target is impossible. This makes it easy to justify quitting the diet altogether to oneself, which was always subconsciously the goal of this approach.
But as others have noted, it often doesn't seem to be sustainable as your body will react to that kind of calorie deficit.
My max. sustainable weight loss rate seems to be about half a kilo a week. Any more and I start yoyo-ing.
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.
by switching antidepressants. the one I was on before caused weight gain and sugar cravings. I gained 40lbs when I started taking it and lost it when I stopped. I just suddenly found sugar and carbs unappetizing, whereas before I'd get intense cravings.
the experience further convinced me that weight regulation is metabolic or something. I used zero self-control, diet or exercise, and a chemical change brought me back to a healthy weight. my eating habits changed but it was subconscious, not willpower.
2 months is hard.
2 years is really hard
Yeah, loosing 2 kg/week for two years is physically impossible for almost all obese people.
At least for me, we're talking massive amounts of water, by the way. ~500ml every 2-3 hours, all day for the whole time.
Ayran/yoghurt with more salt and water works better, likely because of the salt, but I've gotten too many small kidney stones that way - 100% sure, because I had to painfully piss them out and cut my urethra several times. And, well, yeah, bring a portaloo everywhere.
The hunger gets to me every week, though, in which case I found it's OK to eat a lot of protein/fat (eggs, cheese, meat) for a day. Well, by a lot I mean maybe 3 times the normal food intake.
I drink more water than most and I usually go through 4-5 litres in a regular work day.
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.
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!
So the body has definitely way to sense and adjust in some areas.
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!
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.
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.
Have a good one!
I disagree. The reason I disagree is the impact of the different definitions on the original statement I was challenging:
> if a body could run itself more efficiently then it would by default.
Using my definition of "efficiency", this statement strikes me as self-evidently true.
Using your definition of "efficiency", this statement strikes me as probably false and strongly contradicts my priors. After all, every system in the face of input energy restrictions must do less total work.
So, if I accept your definition (which I'm happy to do for the conversation, since it's just a semantic difference), I think this statement is much less likely to be accurate, and certainly isn't self-evident.
Output / energy is the consensus definition of what it means to be efficient. The commenter you are replying to is being kind, but I guess I’m a little more callous…
Are you comfortable continuing with such a confusing definition of efficiency?
My opinion is that you are not recognizing the value of operating in a less-efficient (lower MPG, more power) mode. We can all spend more or less energy in a day as a function of the things we do. To me, it seems like you’re not recognizing this fact.
As I said above, the bulk of calories consumed in a day for a typical person are upkeep, not exercise related. You do not need to factor it into the overall equation. The changes are not significant enough.
"Starvation mode" theory is that the upkeep of the body changes significantly when calories are lower, preventing the body from losing weight. It's just not true. There are secondary effects (lethargy, no energy for increased exercise for athletes) but the vast majority of obese people do not exercise significantly to begin with so these effects can likewise be ignored. The baseline caloric upkeep -- which is something like 70+% of calorie burn for almost all fat people -- will never significantly change in terms of its efficiency. This is why you will always lose weight on a calorie restricted diet, even without exercise.
Hopefully this clears things up for you.
Of course, this is no way to live long term, but in a starvation situation it makes sense to reduce energy demand to the absolute minimum
Those effects I believe are also correlated with extremely low bodyfat moreso than a calorie deficit diet. In most cases a healthy person's body will simply consume fat to account for a deficit in the diet.
We unfortunately have a lot of data about starvation. The effects on the body are very clear. Body fat will go first. Most americans are in absolutely no danger.
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".
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.
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.
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.
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.
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.
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.
Only an approximation but seems to roughly fit many "measurements" by smart watches for both males and females of different weight ranges.
North Americans typically just use Calories for food and excerise contexts. Small c calories is really just used for science.
Apparently it does if you went on too many yoyo diets. Look up reverse dieting to increase your sustaining calorie level again, it works in both directions. Its more or less the efficiency with which your metabolism functions
I liked Jeff Nippards Video with Eric Trexler on the topic https://www.youtube.com/watch?v=xiYJW9pViaM https://www.researchgate.net/profile/Eric-Trexler
From 2019
They're certainly far better sources than unqualified randos on the Internet being that they're educated in specifically this. If you don't agree with that, then you're epistemology is completely broken. Of course, it doesn't mean they're right, but it does mean they're the best first approximation for someone who isn't themselves an expert.
The claim was about where this information is propagated, so don't start fighting with me about whether it's true or not, which I specifically did not make a claim on. Your original claim about who is propagating this information is just false. You're disagreeing with experts, not just "people who believe they are on calorie restricted diets, but who are actually eating more than they think." It doesn't mean you're wrong, but it means you think you know better than people trained in this specifically, which you may or may not, throwaway09223.
"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.
Poster means from an evolutionary point of view, not a societal/modern individual point of view.
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]
Don't suppose you see the article you're commenting on.
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.
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.