Just so we’re on the same page, I agree with you Gruntled that there isn’t a ‘starvation mode’ as per what your friends are believing and going around saying. It’s not going to happen to someone who is overweight or of normal weight unless they have something weird going on medically. They are misinformed about ‘starvation mode’.
And they die as a result.
You’re comparing apples to oranges. Someone who is in starvation mode and is also exercising most definitely will lose weight because they are running at such a calorie deficit to begin with. In which case, they body will start breaking down proteins from muscle and internal organs to try to somehow come up with some additional calories.
ETA: Important distinction in starvation mode you haven’t stopped burning calories, your body is trying to burn less, so to that end, your metabolism slows down. But if you do use calories, no matter how much your body is trying to hang onto them, you will be using them and you will lose weight as a result as the weight is being drawn from fat stores (then proteins when thos resources are used up).
In other words, the weight loss would continue unabated until he starved to death.
So…what happened to that “weight loss plateau”? Where is the “starvation mode” that causes him to stop losing weight?
Nobody is claiming that you can’t starve to death, as you obviously can. However, the energy equation is affected by metabolism and body functions. It doesn’t just take 1000 calories to do one thing every time. If you do something energetically and vigorously, you burn more calories than if you’re extremely tired and doing the bare minimum to achieve the effect.
Let’s posit a diet hypothetical:
Let’s say Joe’s resting metabolic rate is 1500 calories. That’s if he lies in bed all day.
Let’s say Joe works out a good deal and burns 500 calories a day from exercise.
He burns another 1000 calories from going to work, cleaning the house, and generally being an active human being.
Now Joe normally eats 3500 calories a day, but burns only 3000, so he has gained some weight from this regimen. Now let’s say he consumes only 1000 calories a day, for a net difference of -2000 calories. What the ‘equation’ would say is that they should always lose a pound (3500 calories) every 0.57 days. Except that’s not what happens.
His resting metabolic rate changes because his body is shutting down. His hair and nails aren’t regrowing as fast. The body’s trying to compensate for itself. He feels unenergetic, and lethargic. Because the body is burning off muscle instead of fat (as it will do when calories are so low), he no longer needs 1500 calories after a little while. So let’s say for the sake of example he now needs 1000 to maintain what his body is doing.
He’s too tired to exercise as well. He forces himself to work out the same amount of time, but he can’t work out as vigorously, so he burns 200 calories.
He’s sleeping an extra hour a night and basically sits around as much as possible because he’s so tired. He doesn’t unconsciously fidget as much. He wears clothes twice so he doesn’t have to lug his laundry up and down the stairs, whatever. So, instead of burning 1000 calories, he burns 300.
Because he’s eating so little in this equation, he still comes out 500 calories ahead, but now it takes 7 days to lose a pound! And the more he starves himself, the more muscle he burns off and the more metabolism drops … and if he goes off the diet, he gets fat more easily because his metabolism sucks.
It’s a simple energy formula.
It doesn’t matter if the 1000 calorie energy deficit comes from burning an extra 1000 calories due to exertion, or eating 1000 calories less per day than needed - in other words, a diet. 1000 calories burned by the body and not replaced by 1000 calories worth of food energy will result on 1000 calories worth of energy taken from the body’s energy supply. Resulting in 1000 calories worth of weight loss.
Again, where is this mythical “starvation mode” in the above case? When and how does it happen?
No, but his body has set itself up so that it no longer takes that many calories, trying to be more efficient. Or he feels so awful that he faints from hunger or otherwise DOESN’T CHOP THE WOOD. So it’s not irrelevant.
I don’t understand why this is hard for you to understand. Humans are not pre-programed machines that will continue to do the same actions no matter how they feel. Insisting on using math alone when dealing with humans is not going to work. You have to observe the behaviors first before you can calculate the calories used.
This is key to the OP:
Bolding mine. This is where the people Gruntled is quoting are simply mistaken. Yes, you lose weight in starvation mode if your calorie output exceeds calorie input.
Yes, he would lose weight. See above post. The confusion is that the people you were quoting were saying there would be zero weight loss, which is wrong.
I think your question is getting needlessly frustrating on both sides because the factoid that the people you were quoting think weight loss would completely stop has gotten lost in the thread.
ETA: starvation mode is playing a role in the wood chopping. The guy’s metabolic-dependent functions are still slowed down to try to conserve calories. He is using them anyway.
ETA: and yo-yo dieting so you go through cycles of starvation-mode and plentiful eating can make your metabolism screwy.
Thanks. This was my point.
Right. These (fat) co-workers are walking around saying things like “i need to eat a snack or I’ll go into starvation mode and stop losing weight”. :rolleyes: Then they waddle off to the breakroom and grab that last Krispy Kreme.
We were all agreeing with you, as far as I can tell.
Wait, you’re saying that even if Bob and Joe each weigh 180 and each chop wood for 3 hours, that if Joe is in “starvation mode” that he will burn fewer calories chopping the wood as Bob?
Gruntled - both the basal metabolic rate and the amount of calories someone usually burns in a day is highly individual (depending on weight, muscle mass, activity level, genetics) and can change quite a bit according to circumstances. Weight loss is far from the only consequence of inadequate caloric intake. All functions of the body require energy and if there is a severe calorie deficit the soft tissues of the body are not automatically sacrificed while everything else functions normally.
In the case of your wood chopper, that 1000 calories needed for exertion could be gleaned by his body wholly or partly by reducing his overall temperature and redirecting the energy normally used for non-essential organ function and the reproductive system, rather than by breaking down his muscle or fat mass.
With prolonged starvation of course extensive fat loss and muscle wasting will occur, but other parts of the body are often sacrificed during this process. This is why semi-starvation diets are not recommended by most health care professionals - the risk of damage to other bodily functions is too great.
Do some research on what happens to people with anorexia nervosa, the process of starvation is well-recorded in these cases and there are tons of studies to read about the effects on the human body and metabolism. Anorexics have unsually low levels of leptin (hormone regulating energy intake, expenditure, and fat mass) and low BMR (controlled for their total weight and fat percentage), and these effects continue even when they have returned to a normal weight, for example.
Lanugo is the growth of hair, btw, not the loss of it. It’s seen in people whose body temperature has been greatly reduced by starvation and is a last-ditch attempt to keep warmth next to the skin.
That’s what I said. 
The baseline calories for chopping wood should be computed in terms of the energy it takes to lift the axe up and down. It’s a physics problem. But that’s not the amount of calories you burn.
Think about walking up stairs. A 180 lb person walks up 10 feet. There is some minimum amount of energy to do that. It’s a physics problem to calculate the amount of energy it takes to lift 180 lbs 10 feet. Let’s call that X amount of calories. However, that’s not the amount of calories your body burns. Your body burns more than that. Call the difference Y where X+Y is the amount of calories you burn walking up the stairs. That Y value is different for different people. And it will be different depending on your personal metabolism. If you have a lot of food, Y will be big. If you have no food, your body will attempt to make Y as small as possible.
Also think about it like a car. It takes a certain amount of energy to make a car go 1 mile. Gasoline has a certain amount of energy per unit. But you can’t just compute the energy required and say X amount of gas will be sufficient. You have to look at the efficiency of the engine. Most of the gas energy is lost to heat. Some engines are better at conserving that energy than others. So different cars will use differents amount of gas per mile. Even your own car can be made to perform differently depending on the performance chip in the computer.
IANAD, but my educational background is in a field related to how the body works.
So, having said that, a few years ago I was reading a large number of abstracts on pubmed on this very subject (starvation and overfeeding and how they affect metabolism). Some things I remember reading were
- People are different. If you deprive person A of calories, they will lose almost no weight while person B loses tons. One person may lose tons of fat, while another loses tons of lean muscle. So it varies drastically from person to person.
As an example, they might decrease calories by 35,000 (as an estimate) over a month. The results would be one person might lose 10 pounds of pure fat, while another loses 2-3 pounds of muscle and almost no fat.
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The metabolism per pound of fat free mass only goes down about 10% when you are starving. But your physical activity slows drastically. So the combo of less energy & FFM that is using 10% less calories results in a major metabolic slowdown.
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As far as your metabolism being ruined, your bodyweight is held in homeostatis by a variety of chemicals, signals and hormones. However if you start losing weight, the homeostatis shifts to make you gain the weight back. So in that regards, yes your metabolism is ruined and arguably will remain so until you gain the weight back.
Fluiddruid already explained it, with maths, but for this particular example what happens is that if one of these guys is in ‘starvation mode’ he won’t be spending 2,500 calories to maintain his weight. The guy eating normally might spend that much, but the starving guy’s systems shut down, so maybe he only spends 1500 calories ‘maintaining his weight’. Then he can spend 1000 calories chopping wood (or maybe only 800, because he chops slower) for a few weeks, until he gets sick and dies.
Everyone is just making up numbers, and it is hard to get a definitive answer, because the science is not clear, and different studies get different results, plus, it depends on how you define your terms. There is plenty of confusion, and room for people to believe what they want to believe.
Yes. If the job takes 1,000 calories, they will each burn 1,000 for the wood chopping. But Bob uses 500 calories breathing, working his liver and kidneys, Joe may only use 300 calories to breathe and work his liver and kidneys, because his body is withholding a bit.
Bob’s total 1,500. Joes’ 1,300.
Others have explained with much better detail already how exactly starvation mode works and does affect dieting efforts. However, I would also like to note that normal people in normal situations speak casually and shorthand, not scientifically exact. So they simplify and exaggerate.
Normal people say “The sun rises in the East” and “Sunset today is 7 PM” not because they believe in a geocentric system, but because it’s simpler.
So, while literally the statement that people stop loosing weight in starvation mode is not correct, the idea expressed is true and well-known. That’s why every serious doctor - who wants overweight people to loose weight for health reasons - will warn against drastic losses and drastic cuts, and every serious diet plan by professionals will contain advice along “Don’t go hungry by skipping lunch to save calories, it might trigger problems”. That’s the plateau that Swallowed my cellphone and fluiddruid and others were referring to, and overweight people who want to loose weight are smart if they follow good advice and diet sensible instead of crash-dieting.
Of course, if overweight people use this as an excuse not to diet at all, that’s wrong. Similar, the idea of keeping on snacking to avoid hunger pangs (that could lead to later overating) is in itself correct. If they snack on a high-calorie item like a donut, however, it’s stupid and wrong; if they snack on a low-calorie item like an apple, it’s right.
You have to remember that the purpose of good diet for medical reason is to loose weight permanently and keep it off, not loose a few pounds for bikini season. So any drastic changes that lead to hunger or monotony or otherwise not able to keep doing for months and years are useless. Weight Watchers (I am not affiliated with them) is a good program for many people because it aims at long-term change; so are proper weight-loss clinics which teach healthy cooking and how to snack on low-calorie and how to exercise, so that people can change their lifestyle back home, because otherwise, the pounds will get back on quickly.