Does your body go into starvation mode?
April 30, 2011 3:11 PM   Subscribe

Nutrition filter: I have read a lot of articles about how if you consume less than 1200 calories your body goes into "starvation mode." I have read other articles that claim it is just a myth. Anyone have any sense of the truth of this? Thank for your help!
posted by Equiprimordial to Health & Fitness (12 answers total) 9 users marked this as a favorite
Nutrition is an inexact science, and weight management varies from body to body. If I eat less than 2500 calories per day or so, I lose a tremendous amount of weight. Three years ago, I had a tremendously difficult time losing weight on 1500 calories per day with vigorous, daily exercise. What's different, other than metabolism? Nobody, including the nutritionists and endocrinologist I've seen, seems to know.

So you'll probably get varying answers, but I think the closest answer is, it could be true for some people, and for others, not.
posted by xingcat at 3:20 PM on April 30, 2011 [3 favorites]

You do go into starvation mode at some point, 1200 is a ridiculous number but the web likes numbers so there it is. Some people will define "starvation mode" as the point at which your weight loss stalls because your metabolism is undergoing too much stress from calorie restriction. The problem with that is there are so many lifestyle factors that have an impact on plateaus that it is difficult to distinguish calorie consumption from other issues. I would define "starvation mode" as when your body begins to consume muscle for energy. This is very bad, but again is variable among individuals.
posted by boobjob at 3:31 PM on April 30, 2011

This depends on so many details (sex, age, height/weight, amount of exercise, what those calories consist of, etc.) it's impossible to answer with a single number of calories. Can people starve? Sure. Does your body do wacky things to try and keep you from dying when that happens? Yes, thankfully.

My personal experience suggests that 1200 calories is low enough that I get lethargic and stop moving, and shockingly, I don't tend to lose much weight that way. Admittedly, those 1200 calories were almost entirely Dr. Pepper, and I wasn't really interested in losing weight at the time.

I've also lost up to five pounds during really bad weeks where I couldn't eat or drink anything because I puked it all back up. And, in case any of my old camp counselors are reading: that was altitude sickness, not homesickness, you non-medical-professionals, you.
posted by SMPA at 3:36 PM on April 30, 2011 [2 favorites]

The phenomenon is real, the myth is that you can name a specific calorie amount for which it happens.
posted by Rhomboid at 3:37 PM on April 30, 2011 [4 favorites]

It is a ridiculous oversimplification of the process of your body downregulating its metabolism in response to insufficient caloric intake over long periods of time, often combined with severe stress on the body in the form of excessive exercise and whatnot. Your body does slow down its metabolism, it's an evolutionary advantage to do so when food isn't present, but it's way, way overblown in popular culture. Some things to note:

"Insufficient caloric intake" generally means half of your daily caloric needs or less. This will vary wildly from person to person based on size, activity level, etc. A small person may only need 1600 calories a day, and thus they'd need to eat under 800 to starve. A large person performing a lot of heavy labor may need 4000 calories a day, and thus more than 1200 would cause issues. There's also flexibility here. A very obese person can handle much larger drops in calories than someone of normal body fat, because someone who is 300lbs and 40% body fat does not need the same number of calories as someone who is 300lbs and 15% body fat. Also, a young, active person (think male teenage athlete) who can eat 4000 calories and not gain a pound will not necessarily hit starvation mode if they're only eating 2000--their athletic performance will drop, which means their activity level will not be as intense, which means their body will not burn as many calories. If they keep pushing themselves in the gym while starving, that's another story.

"Excess exercise" is going to be in the form of extremely metabolically intense workouts (very heavy lifting, heavy conditioning work, long endurance training) without sufficient rest days and recovery methods (sleep, etc) over a period of months. Someone who is engaging in a lot of very heavy exercise will burn out a lot faster than someone who's relatively inactive but starving themselves.

"Long period of time" = months and months. Not a day, not a week, not a month. Again, flexibility here, if you're exercising hard five hours a day and not sleeping you'll be hitting the wall sooner than someone who's not.

"Metabolic downregulation" does not mean "I'm not losing any weight!" It means if you have a deficit of 60%, your body starts responding as if you're only eating 50%. That is, if you need 2000 calories a day, and you're eating 800, after a while you start losing weight at the same rate you would as if you were eating 1000. You're still losing weight, but slower than expected. Exceptions come in the form of anorexics, etc, people whose bodies are literally shutting down and dying and therefore just aren't using whatever calories are going in.

However--the reason to not cut your calories to that level is not because you don't want to enter "starvation mode," it's because the more you cut your calories, the more likely you are to start cutting muscle along with the fat. This is unhealthy and you end up looking like crap at the end of the weight-loss period because you're skinny-fat. The only reason to go on an extremely calorie-restricted diet is if you're doing carb-cycling and refeeds and other diet voodoo tricks in the last few weeks before a physique competition or if you're very overweight and it's crucial to your health that you kick start the weight loss. The former is not healthy and the equivalent of a top-level athlete training on a bad knee to prep for the Olympics--not good, but you do it for the competition. The latter should not be carried on for long periods of time.
posted by schroedinger at 3:43 PM on April 30, 2011 [13 favorites]

true dat...when you hear reccomendations like 2000 cal/day and whatnot and US Reccomended Daily Allowances of this that and the other, keep in mind that those are all based on large population studies of all different sizes and shapes of people, not you in particular. however, (and it's been since high school since i've done this) you can get a better idea of your caloric needs by punching a few numbers (height, weight, age, heart rate, blood pressure, breathing rate, etc) into some simple formulas.
are you trying to lose weight? ...yeah, starvation diets aren't going to do it. they tend to work for about a week and then your body goes into 'i'm hanging onto every calorie you put into me' mode.
losing weight, like gaining it, is a gradual process. moderate calorie restriction+healthier eating habits+exercise=success.
that being said (and i can vouch for this one myself), there's been a ton of research to support the fact that calorie restriction (~90% of 'normal') can actually slow the aging process...lots of studies with mice and such...the theory being that your body is working more efficently with what it's given and your cells aren't getting all clogged up with waste products. i eat like a bird, and always have (actually birds eat a fuck-ton, but u get my drift...) and am often mistaken for being ~15 years younger...which can be awesome, but can also be a drag if your looking to be taken seriously based on your years of experience...YMMV
posted by sexyrobot at 3:48 PM on April 30, 2011

Just throwing in a link I found interesting - a study where mice gained weight despite reduced caloric intake, and discussion thereof.
posted by Earl the Polliwog at 5:02 PM on April 30, 2011

[sorry folks, this thread was becoming 50% about "fat anorexics" can you be a little bit more specific in your answers please? thank you.]
posted by jessamyn at 7:09 PM on April 30, 2011

The 1200 calorie situation was conceived and developed for lab use. Why? Because that shit can be controlled in a lab, and it has a VERY specific reason for existing in a lab. AND, it is monitored VERY closely by professionals.

One should know that doing this AT HOME, without medical supervision or immediate biofeedback analysis, you are playing a dangerous game.

Is it effective? In the lab-yes! Is it dangerous outside of the lab? Yes.
posted by hal_c_on at 7:58 PM on April 30, 2011

There is a point at which your body will slow your metabolism in order to conserve energy, and the reason it does this is because evolutionarily, there's a benefit to not starving to death when food is sometimes plentiful and sometimes scarce. You wouldn't want to die of starvation after a week of not eating much when the hunters are about to bring home a fresh buffalo for you to gorge on. Your body will also ramp up your metabolism if you eat substantially more than usual, which is why some people have trouble gaining weight, even on very high calorie diets. But everyone above is right that there's no magic number that tells you when those processes will start to kick in for your body. You need to play around with what, when, and how much you're eating to find the diet that makes your body feel good and work the way you want it to.
posted by decathecting at 8:24 PM on April 30, 2011

In addition to what's been said above, I'm a serious believer in the psychological aspect of "starvation mode". It's a lot easier to cut calories by eating a little less, consistently, than to eat basically nothing for a short burst which will inevitably be derailed by a binge of "forbidden" foods.

One example from my own life - I find that if I don't eat breakfast, I have much stronger cravings for junky snacks in the afternoon. I'm pretty sure that I get fewer total calories with three square meals than I do by skipping a meal and then gorging in the afternoon. Even if it's mathematically true that if I ate two meals a day, I'd theoretically lose weight faster. I'm not going to stick to the two meal plan, so the rest is moot. "Starvation mode" or no.
posted by Sara C. at 10:35 PM on April 30, 2011

Allied POWs in the Pacific during WW2 got a lot less than 1200 calories a day. Their weight loss didn't stall. Ditto for people who've had bariatric surgery. The main problem with very low calorie diets is that, under everyday circumstances, they're not sustainable (unless you have a mental illness). But if you don't have a choice (that is, there's nothing to eat), or you've fooled your brain into thinking you've eaten a lot (eg lap band), you'll lose weight on 1200 calories, and you'll keep losing it til you start eating more or you die (which could take a very long time).
posted by obiwanwasabi at 10:52 PM on April 30, 2011 [2 favorites]

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