Wow! 20 years ago I was helping my ex father in law with some construction work. He and all of his buddies were tweakers and a lot of them smelled funny. I always thought it had something to do with meth but now I'm guessing they were just burning muscle.
Losing weight too fast is bad, but a 500 cal/day deficit is healthy and can drop a pound a week. It is important to exercise and preferably train with free weights to maintain muscle mass. It's actually possible for untrained men to gain muscle while losing weight (haven't seen results for women).
BCAA are not zero calorie, contrary to popular wisdom, so you can't consume them during a fast. It's a regulatory loophole that amino acids don't need to be counted towards the caloric total.
If you do intermittent fasting (16-24h), you can eat it during the non-fasting periods and it should help with muscle loss. Also, you can do HIIT during longer fasts to keep muscles "in demand" so that proteins aren't recycled by your body to usual extent. There was some study about it somewhere...
While not healthy to literally starve yourself, getting your calories from stored fat is absolutely safe. There are dozens of documented cases of people subsisting on vitimins/broth and their own fat for over a year. Proper electrolytes all but eliminate most issues you suggest, only applicable to a pure starvation diet. Conflating the 2 is either uninformed or dishonest.
He's right, it's FUD. Studies [1] show that protein consumption goes down over the course of fasting, and that only makes sense. To borrow an analogy from [1] if your body is storing up energy for a rainy day like logs for a fire, when the power goes out are you going to chop up your axe and couch for firewood? Of course not, that's insane.
Evolutionarily, it makes the most sense to conserve your muscle so you can hunt down and kill food, not waste away into a fatty blob and make it a few extra days until what, someone finds you? That's why your body's HGH production spikes to hundreds of percent of baseline, to conserve your muscles.
Protein is always consumed as muscles turn over, but most tissues in your body can consume glucose OR ketones -- even your brain can switch over to consuming ketones as its primary source of energy. The remaining glucose requirements are met via gluconeogenesis, from multiple sources, including the glycerol backbone of triglycerides. However, there's plenty of non-muscle sources of protein in your body too and they are most definitely consumed as part of autophagy.
Body composition is better after fasting than caloric restriction even in the event of equal amount of mass re-gain (i.e. regain after CR is fat, after ADF is muscle/lean): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5042570/
It's not FUD, none of your sources are relevant for the context of this thread, and you and the other poster have completely misunderstood this context.
There's a lot of conflicting data. However I think the general thrust is that you should not try to lose weight unless you are accurately measuring how much lean mass you are losing. Otherwise it's very easy to lose a lot of muscle, which is probably not healthy unless you are extremely obese. Crucially your current body composition matters quite a lot. People under 10% body fat are going to start losing really important vital body mass. People over 25% body fat will lose mostly fat. But people have wildly different body compositions and a BMI of 25 doesn't mean 25% body fat. Again, accurate measurement is crucial.
Personally, I focus on maximizing a variety of physical measurements. (How long I can hold various yoga poses without discomfort, how many situps I can do, how far I can bike/walk/swim before I begin to feel fatigued, etc.) I definitely think optimizing weight downward is a poor strategy for improved health.
> While not healthy to literally starve yourself, getting your calories from stored fat is absolutely safe.
Sure, if you can guarantee that you're burning fat. That's clearly not what I said, because "weight loss" does not necessarily entail "fat loss". If all you're doing is looking at the scale, unless you take certain precautions, then you're also losing muscle mass. Doing this "quickly", which was another qualifier I stated, can be dangerous.
> Proper electrolytes all but eliminate most issues you suggest, only applicable to a pure starvation diet.
You need more than electrolytes to prevent muscle loss. Devoting more of your caloric budget to protein slows muscle loss considerably, and adding resistance training can prevent muscle loss entirely.
But like I said, just focusing on rapid weight loss with no other considerations is dangerous.
In general, muscle is 'consumed' before 'fat'. Quotes since it is more complex than just what regular muscle and fatty tissues do.
> While not healthy to literally starve yourself, getting your calories from stored fat is absolutely safe.
No one will disagree with you there, but for most normal healthy people with regular muscle/fat content (or a bit too much) it takes a while for your body to decide it is a good idea to start creating toxins (ketones, which are quite harmless in smaller quantities) which are the result of fat conversion in a starvation diet.
No, but the optimum solution to survive long term starvation is to dump as much muscle mass as possible to minimize your daily calorie burn. Alongside that the body minimizes the energy spent fighting long term problems like cancer by reducing the amount of antioxidants produced etc.
Some strength is still required, so their are feedback mechanisms limiting this loss. However, on a diet you are not in pure survival mode so you probably don't want to make those same sacrifices.
That's a myth. Extra muscle doesn't contribute very much to resting metabolic rate. Fat isn't metabolically "free" either; it takes a lot of energy just to move adipose tissue around.
In starvation it's calories not pounds that's critical, also it's not a question of resting metabolic rate alone.
Fat contains contains more than twice the energy per lb and every motion you do requires energy to move every lb of body weight. Net result storing energy in Fat takes ~1/3 the energy to maintain.
So, sure it's not a huge difference per day. But, the difference between dying in 100 days or 100 + X days could make a huge difference.
"Thirty-two nonobese men underwent sequential overfeeding (1 wk at +50% of energy needs), CR (3 wk at -50% of energy needs), and refeeding (2 wk at +50% of energy needs). AT and its determinants were measured together with body composition as assessed with the use of quantitative magnetic resonance, whole-body MRI, isotope dilution, and nitrogen and fluid balances." https://www.ncbi.nlm.nih.gov/m/pubmed/26399868/
So, over 6 weeks they had zero calorie deficit but even 3 weeks of starvation result cost them 5% of their skeletal muscles lower metabolic rate, and presumably increased fat. Note: Interment fasting has nothing to do with this, it takes the body several days respond to starvation a few hours don't matter as long as net calories over 2-3 days are maintained.
PS: What studies? I see a linked to an article about people over estimates of mussels energy requirements not a counter argument. You’re demonstrably wrong from both experiment and basic biochemistry.
That's actually different, you're talking about calorie restriction (-50% of needs), what we've been discussing is fasting (0% of needs). There are substantial physiological differences between the two modes, and that study is not relevant to this conversation. Fasting actually improves your body composition (reduces proportion of fat : muscle) [5]. Further, even if you regain all the weight you lost, you'll still have a better body composition after fasting vs. CR [6].
Speculatively, even the reduced amount of food will suppress HGH production - while total abstention yields many hundreds of percent increase in levels [3, 4]. HGH is known to be responsible conserving muscle and improving body composition.
It's been shown in studies that fasting raises your metabolic rate [1, 2] (again, offer not applicable to CR, by your own study and some others I don't have on hand right now). This is likely due at least in part to the production of norepinephrine during fasting. This further substantiates my point that we're talking about two different modes of operation.
CR != Fasting.
FWIW I agree with you, reducing your calorie consumption 50% but maintaining your 3-a-day plus snacks eating schedule is not great for you ("starvation") and likely damn hard to stick to. Weight Watchers themselves published a study that showed it just doesn't work. [7] This is what they were testing during the Minnesota starvation experiment and that didn't go well, to say the least. What my review of numerous studies indicates, is that the relationship does not extend to reducing your caloric intake 100% (obviously, intermittently for some value of intermittent). What it appears is being re-discovered is that it's not how much you eat, but what you eat, and how when/how often.
I specifically commented on someone saying “our ancestors would just die of starvation”. So, if you want to talk about short term fasting then that’s cool but really not related to this thread of conversation.
Anyway, I agree under 2 weeks of fasting is not starvation. The body does not go into starvation mode over a few days becase it’s extremely expensive to cycle building up and removing skeletal muscle.
PS: It generally takes 24 to 72 hours for food to move through your digestive tract. In the very short term fasting you get excess energy because digestion takes energy. But extend that for 3+ weeks and very different things start happening.
My reading implies that the number of muscle cells does not change and that protein in the muscles is rapidly rebuilt upon re-feeding.
Entering 'starvation mode' from studies appears to happen around day 3-5 of fasting, there's charts in the links I provided. That's when the new energy distribution is in full effect and the brain is deriving most of its required energy from ketone bodies. If you have some interesting stuff to read about another shift that happens around 2 weeks I'd love to check it out, I'm always looking to learn more about this stuff. When 'starvation mode' switches to dying mode appears to be when all your fat stores are exhausted and the body no longer has fat to consume for energy. If you're obese that can be 12 months away or more. Most people who fast for long periods note the switchover happens when their breath turns sweet and a real feeling of hunger returns -- that's obviously when they break the fast so as not to die.
That is absolutely not true. How do you plan to get food when you have the same amount of fat, and way less muscle to drag it around with? You'd be a blobby puddle until someone came to save you. That's not realistic, we'd all be so dead.
What is long term starvation in this context? Is a week already long term? The second point also goes against what I recall reading about cancer in calorie-restricted animals (I may be wrong).
The basal metabolic rate angle is interesting, did not directly come to mind.
In general, muscle is 'consumed' before 'fat'. Quotes since it is more complex than just what regular muscle and fatty tissues do.
Not "in general." Only specifically in cases of starvation or caloric deficit. In general, your body burns carbs, then fat, and then muscle. Muscle is by far the least efficient energy source, so the body spares muscle in normal circumstances and only consumes muscle in times of extended caloric deficit, like fasting, starvation, marathons, etc.
> In general, your body burns carbs, then fat, and then muscle. Muscle is by far the least efficient energy source, so the body spares muscle in normal circumstances and only consumes muscle in times of extended caloric deficit
This is a common belief but it's not true. You can't prevent your body from burning muscle in any kind of caloric deficit, you can only stimulate protein synthesis to counterbalance it by 1) ingesting high amounts of protein and 2) resistance training.
Yeah, sorry bud, you're just not in the right on this one. Your body always turns over muscle, sure, so some is going to be consumed. Your body produces huge quantities of HGH during starvation specifically to conserve protein and protein consumption goes down during fasting compared to steady-state. Otherwise our ancestors in periods of famine would turn into fatty puddles unable to drag themselves around. Starving means you need to get food, that's why noradrenaline levels go up, HGH production spikes (which many studies show changes your body composition to favor muscle over fat), your body switches to consuming primarily fat, and yes, some protein but not all protein is muscle. Your body also switches to producing what little glucose it actually needs via gluconeogenesis - which has many feedstocks including the glycerol backbones from triglycerides and yes, protein.
But to say your body prefers to burn muscle over fat when starving is ridiculous, and just not supported by facts.
Some muscle is consumed in a state of caloric deficit, yes. But muscle isn't the body's first choice for fuel until you enter into a state of extended caloric deficit. If the opposite were true, then triathletes would consume a pound or more of muscle during their training activities and especially during competitive events, instead of burning visually significant quantities of fat.
> But muscle isn't the body's first choice for fuel until you enter into a state of extended caloric deficit.
I'm honestly puzzled how people in this thread got the idea that I said that muscle was a preferred fuel. Literally no sequence of words I actually used imply this statement.
> it takes a while for your body to decide it is a good idea to start creating toxins (ketones, which are quite harmless in smaller quantities) which are the result of fat conversion in a starvation diet.
Ketones are created when your body doesn't have sugar to convert into energy. This process can take as little as 12 hours, and in no way whatsoever requires a "starvation diet"
