Dr. weight loss advice not following laws of physics e.g., prison camps
November 17, 2017 2:38 PM   Subscribe

Thought experiment: two conflicting concepts regarding weight loss where the math doesn't add up and is completely contrary to real life conditions.

Concept 1: Every doctor and nutritionist I’ve seen and diet papers I’ve read say that if you don’t eat enough calories and exercise too much, you will not lose weight because your body needs a certain amount of calories to boost the metabolism, therefore it holds on to the fat and goes into “starvation mode”.

Concept 2: Victims of prison camps, famine, army camps and other situations whether there is physical labor or not, where they are literally starving are horrifically skinny and skeleton-like.
“According to an educational website run by the London Jewish Cultural Centre, diets in the Nazi-run camps consisted of imitation coffee or tea for breakfast, “watery soup” for lunch and 300 grams of bread for dinner, together with “a tiny piece of sausage, or margarine, marmalade or cheese.”

Far from not “exercising a lot,” many prisoners were forced to do tough manual labor in slave-like conditions.

The site referenced above says: “The lack of food, poor diet and hard labor caused the prisoners to suffer from starvation sickness. They lost weight and muscle tissue and many thousands died.”

Thoughts: I know that the metabolism is complicated. However, I’m in the sciences, and have taken biochemistry and physics, and it just seems so logical that Concept 1 is wrong, well, because of math. A deficit in caloric intake results in weight loss, muscle and fat.
This is proven throughout the ages and now with Concept 2. I’ve never seen an overweight long term prisoner of war or victim of famine, but of course that doesn’t mean there aren’t any.
Also, if Concept 1 is so off the mark and illogical, how are doctors and nutritionists getting away with teaching people this?

I would love to hear your thoughts on this!


(If we could please steer away from the topics of the obvious horrors of wars and economical issues and keep in mind that this is a math/physics question and health and nutrition are important but not accounted for here, that would be super.)
posted by Arachnophile to Science & Nature (22 answers total) 4 users marked this as a favorite
P.S., sorry, can't edit, but I also wanted to mention anorexics seem to fit into Concept 2.
posted by Arachnophile at 2:43 PM on November 17, 2017

Energy doesn't come from nowhere and if you do not eat food, or you eat very little food, you will eventually lose weight (or die from starvation -- that can happen before significant weight loss but still as a result of starvation). I don't think anyone is disputing that. However, before you starve to death you will do incredible damage to your metabolism (it will slow down as much as possible, per concept 1) and your muscles and vital organs (your body will destroy the things you need, like skeletal muscle that allows you to do things and protects your from injury, your heart, which you need for obvious reasons, etc).

For those reasons doctors tend to lean on concept 1 in conversations about reasonable ways to lose weight, even though you have astutely realized that it is not technically true that starving yourself will not result in weight loss.
posted by telegraph at 2:44 PM on November 17, 2017 [12 favorites]

Related: there's still a lot we don't know about the body's metabolism. For instance, studies into what happens to a person's metabolism years after weight loss are relatively new.
posted by purple_bird at 2:52 PM on November 17, 2017 [2 favorites]

Great answers, thanks. Great article purple_bird, it's hard to keep weight off after losing it. But it seems that it's also hard for naturally thin people to gain weight:

"In 1967, a medical researcher, Ethan Sims, carried out an experiment at Vermont state prison in the US. He recruited inmates to eat as much as they could to gain 25% of their body weight, in return for early release from prison.
Some of the volunteers could not reach the target however hard they tried, even though they were eating 10,000 calories a day. Sims's conclusion was that for some, obesity is nearly impossible."

And I don't have a reference, but some studies with gut bacteria in fecal transplants from an obese donor causes some naturally thin recipients to become obese, and vice versa. Some obese patients getting fecal transplants from naturally thin people over time became thin. I asked my genetically thin model friend who eats about 5,000 calories/day to give me a fecal sample for transplant, but she was too grossed out. :)

The body is so fascinating.
posted by Arachnophile at 3:02 PM on November 17, 2017 [1 favorite]

[Hey Arachnophile, this is not a good place for a general discussion - a question is fine, but please don't open the topic up too much or it's gonna get unwieldy. Thanks. ]
posted by restless_nomad (staff) at 3:09 PM on November 17, 2017

In an infinite timescale, yes, the body when starving will metabolize fat. When times are just tough and you're not exactly starving to death your boy is much happier to cannibalize muscle.

Insulin dependant diabetics also have trouble with muscle growth and fat metabolization when exercising with poorly controlled sugars.

Athletes who are not well fed not only have poor 'on the day performance' but will suffer from delayed/suboptimal recovery and mid/long term stunted strength gains. This ends up being (at least in the performance sport arena which is my only real area of expertise) somewhat self regulating - not eating enough results in an inability to work harder regardless of the motivation. The perceived effort may be high, the discomfort may be very high but the measurable power outputs are markedly decreased with very short periods of(well not 'Mal') 'sub'-nutrition.
posted by mce at 3:10 PM on November 17, 2017

A different way of looking at this to consider studies where the participants were overfed by a consistently large number of calories. In most of these, everyone gains weight, but the amount of weight gained varies greatly. The body has a few ways of either conserving energy or removing excess calories that don't necessarily involve moving lipids in and out of your cells. The most effective is something called "non-exercise activity thermogenesis". Here's an excerpt from Stephan Guyenet's The Hungry Brain:
The research of James Levine, an endocrinologist who works with the Mayo Clinic and Arizona State University in Scottsdale, Arizona, explains this puzzling phenomenon. In a carefully controlled overfeeding study, his team showed that the primary reason some people readily burn off excess calories is that they ramp up a form of calorie burning called “non-exercise activity thermogenesis” (NEAT). NEAT is basically a fancy term for fidgeting. When certain people overeat, their brains boost calorie expenditure by making them fidget, change posture frequently, and make other small movements throughout the day. It’s an involuntary process, and Levine’s data show that it can incinerate nearly 700 Calories per day! The “most gifted” of Levine’s subjects gained less than a pound of body fat from eating 1,000 extra Calories per day for eight weeks. Yet the strength of the response was highly variable, and the “least gifted” of Levine’s subjects didn’t increase NEAT at all, shunting all the excess calories into fat tissue and gaining over nine pounds of body fat.

Guyenet Ph.D., Stephan. The Hungry Brain: Outsmarting the Instincts That Make Us Overeat (p. 173). Flatiron Books.
I would wager that particular advice is less about strict physics and more about keeping you motivated to diet and exercise. If you push too hard, you may run into a situation where your brain fights back with things like constraining subconscious movement, reducing your motivation to exercise, or ramping up your hunger. In a situation like a prison camp, someone pointing a gun at your head is pretty good motivation to keep moving, or you may be forced to keep a caloric deficit that you couldn't sustain voluntarily.

If you're interested in the topic further, Guyenet's book is great at going into the neuroscience of appetite and weight regulation.
posted by ayerarcturus at 3:13 PM on November 17, 2017 [3 favorites]

(I should also mention that Dr. Guyenet's book is heavy on science and light on actual advice, but does have a brief chapter about more practical applications towards the end. The biggest thing I got from it is that this topic is remarkably complicated -- there are so many moving parts, and after years of looking there's still no obvious smoking gun or one-size fits all diet plan, despite what many people are selling.)
posted by ayerarcturus at 3:19 PM on November 17, 2017

Scale matters. Your first example is one of adaptive thermogenesis, which an individual dieter can regulate. It's a voluntary calorie deprivation which can be tweaked when hitting a weight-loss plateau. (The metabolic system will adapt and periodically hit plateaus, and there are people, due to genetics as well as previous dieting experiences, especially resistant to losing weight). It's incremental. Your second example is torture, concerning massive food deprivation beyond the control of concentration camp prisoners. On a daily basis, a prisoner ate fewer than half the calories a person needs to survive. Living conditions in the camps made disease rampant, weakening everyone even further and leading to more weight loss.

The average healthy person, the traditional subject of diet-and-nutrition-related research papers, is not a victim of such atrocities. The two "concepts" aren't truly comparable, unless you're an Australian doctor with a foot-in-mouth disorder.
posted by Iris Gambol at 3:21 PM on November 17, 2017 [2 favorites]

The point isn't that your comparison isn't ethical, it's that it isn't correct, because there are factors relating to the very different scenarios of self-regulation by choice vs the enforced starvation and slave work of the concentration camp victims. A person who chooses to diet and exercise is having a very different time mentally and physically than a person who is subjected to starvation and slavery beyond her control.

Consider for a moment how it feels to decide to run fast for two minutes. Now consider how it would feel to be tied behind a moving truck for two minutes. Even with just a mental exercise you can start to understand the difference.
posted by fingersandtoes at 3:53 PM on November 17, 2017 [6 favorites]

I don't understand why you see a conflict here. Many more people would die under those conditions if the body wasn't able to regulate its metabolism to a certain degree.
posted by praemunire at 6:41 PM on November 17, 2017 [7 favorites]

This feels like a thinly veiled way of asking "aren't fat people truly just lazy since diet and exercise always make you lose weight?"

Human bodies have great variation in how they process calories.
posted by masquesoporfavor at 6:44 PM on November 17, 2017 [5 favorites]

I don’t know where you’re getting the idea that anorexics as a rule fit into Concept 2.
posted by kapers at 6:53 PM on November 17, 2017

You're starting out with a weird straw man.

Every doctor and nutritionist I’ve seen and diet papers I’ve read say that if you don’t eat enough calories and exercise too much, you will not lose weight

This is nonsense. No doctor suggests that a calorie deficit and a lot of exercise will prevent you from losing weight: it would be like suggesting the moon is made of cheese. It's obviously the opposite of the truth and no reputable source suggests it.

What is true is that metabolism can and does slow down some in starvation circumstances; (however this effect cannot, obviously, counteract starvation); and furthermore, as purple bird mentions, there seems to be evidence that the slowing can be permanent, causing not only the regaining of the lost weight, but additional weight gain over the long term.
posted by fingersandtoes at 7:26 PM on November 17, 2017 [1 favorite]

You might want to read The Great Starvation Experiment: Ancel Keys and the Men Who Starved for Science by Todd Tucker. In short: Concept 1 is advice for people trying to lose weight. In short "Keep eating a reasonable amount of calories because that's generally a good idea and for healthy weight loss, it's better". People not trying to lose weight (because they don't have enough food or are doing forced labor) definitely lose weight with eating fewer calories over a long period of time. "Starvation mode" is a thing people use to explain some metabolism things but there's a much more complicated calculus to a lot of this.
posted by jessamyn at 8:45 PM on November 17, 2017

Hmm. I would just add, fingersandtoes, that a calorie deficit and a lot of exercise could prevent one from losing weight in some circumstances—not all—in which conditions are right to burn fat but build up muscle. So one wouldn't be losing weight, but would be dramatically changing one's body composition over time to an equivalent or greater heaviness. I don't think the premise is that far afield. But that's also why simplistic concepts of weight and body-mass index (just comparing height to weight) aren't particularly useful here, which unfortunately the literature is only just beginning to make clear. Body composition matters greatly, as do one's gut flora and epigenetics—e.g., if one's ancestors starved during the Great Depression or in concentration camps during the Holocaust, tons of interesting consequences follow for descendents.

Arachnophile, you asked that we not get too far off topic with wars and famine, but those are exactly the conditions that may well presage the seemingly contradictory circumstances you're asking about here. Many doctors' math doesn't account for that at all yet, because it's only just being investigated in recent years. So that's an important thing to consider. Math and physics alone really don't address this discrepancy, which makes it so much more frustrating for people who have been told that if they really wanted it or really tried, they could be smaller or lighter. Definitely read up on some of the research covered in the search results there.
posted by limeonaire at 11:38 PM on November 17, 2017

The topic is pretty grim.

In Scenario 1 the person has access to food and the freedom to eat it when they choose to. The metabolism may slow down due to deprivation, but the body will receive varying numbers of calories at inconsistent times. If your metabolism has slowed because of skipping meals and then you have an influx of calories, maybe many calories at one time, then the body may store those as fat.

In Scenario 2 the person is deprived of food by a third party and does not have the freedom to eat when they want to, since they do not have access to the food. If they were provided with little to no food everyday, the metabolism may slow but there's really very few calories (or no calories) to contribute towards any kind of weight gain or maintenance, especially when they may be forced to do manual labour for much of the day.
posted by kinddieserzeit at 1:38 AM on November 18, 2017

The problem with concept #1 is the food IS available whereas in concept #2 it is not. If you have a large calorie deficit, all sorts of horrible hormonal shit happens, the body does its very best to survive, it slows down metabolic processing - basically goes into low power mode. Your "Maths" solution, doesn't work because it doesn't account for the massive ability of the body to regulate metabolism. Its how we survive famines, back in the days when we had famines, most of the afflicted were not obese to begin with so our bodies need to be able to survive long periods of insufficient calories and they do it well.

In the case of dieters (rather than anorexics of PoWs), psychologically, they will break before significant weight loss can occur and a sudden influx of calories (and lets face it, usually bad calories), those are going straight into fat.
VLCD are dangerous which is why they need to be medically supervised. If you were to attempt it without medical supervision, if you don't "break" and cheat on your diet, you will eventually lose weight, or die.

Good doctors are concerned about your overall and long term health. Eating too little and exercising too much is not good for your health, regardless of whether you manage to lose weight. The faster you lose, the more likely you are to regain. Slow weight loss is the best for your long term health and weight loss success
posted by missmagenta at 3:37 AM on November 18, 2017

I think the simple fact that you’re missing Arachnophile is that the victims of concentration camps were getting *fewer* calories that those required to sustain their bodies even in full "starvation mode". The intent was to kill them whilst extracting the maximum amount of cheap labour from them.

Handwavy thought experiment: Lets say that the human body can just about sustain itself on 1000 calories a day (figure plucked out of the air with no scientific basis) in full 'minimum energy expenditure starvation mode'. What do you expect to happen if you feed someone 500 calories a day? Their body is going to start consuming itself to make up the difference & after about 4-5 months they’re probably going to die.

In ordinary modern life (at least here in the relatively affluent parts of the world), unless you have a serious psychological illness, you *cannot* do this to yourself if food is available: Your internal mental life will become completely dominated by the need to find food & eat it over and above all other needs.
posted by pharm at 5:11 AM on November 18, 2017 [2 favorites]

If you want to focus on the math side of things, consider this: when modeling problems in physics 101, we often assume a frictionless environment and a spherical object with uniform density. That's great for pedagogical purposes, but if you modeled an airplane like that and tried to compare your results to an actual airplane, nothing would add up. I think your internal math on weight gain is making similarly naïve assumptions. Does your mental model assume all calories ingested are treated equally by the digestive system? That all calories ingested are processed by the body, and that 0 calories exit via stool, urine, etc? How about calories that go into making heat? Does your mathematical model account for microflora in the gut, and how many calories they use for their own processes, and what the inputs and outputs of those processes are?
posted by mrgoldenbrown at 10:16 AM on November 18, 2017 [1 favorite]

"Starvation mode," as you describe it in "concept 1," is a myth. What does it even mean to "boost the metabolism"? The body does need a certain amount of fat (for men, it's about 2-5% of total weight; for women, 10-13%) for some metabolic functions, but people with that level of fat generally look very thin (unless they're bodybuilders who have cut for a competition) and have lost a huge amount of fat, usually along with a huge amount of muscle, too.

Energy expenditure does slow down with a long-term calorie deficit, but that's because (1) people who are starving move very little, to conserve energy, and (2) if it's severe, the body stops repairing its organs, ultimately leading to death. With a moderate deficit, you might reach a point of equilibrium where you stop losing weight, but only because you've reduced activity and lost muscle mass, both of which reduce total energy expenditure.
posted by brianogilvie at 3:51 PM on November 18, 2017 [1 favorite]

I think that the "starvation mode" thing is largely hyperbole that gets used as a way to prevent people from trying to lose weight too fast.

Starvation mode is a real thing that does happen where your body prioritises storing calories over burning them. It's ideal for surviving long periods of malnutrition but it cannot overcome physics and if your body absorbs less energy than it expends, you experience a net loss of mass.

But you're not going to voluntarily starve yourself enough for long enough to get your body to do that unless you hire armed guards with questionable scruples to force it.

What they're really telling you is that you can cause various health issues by trying to lose too much weight too fast.
posted by VTX at 1:27 PM on November 21, 2017

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