Starvation mode

Factual Questions
1

I know there are plenty of weight loss calorie counter type threads around here, but I have a particular question about something that seems to be common knowledge but doesn’t exactly make sense to me or the law of thermodynamics. Well here is a little back story to explain what brings me to ask this question…

Being on winter vacation from university I spend most of my days sleeping and most of my nights prowling with friends. That doesn’t leave much time for eating, so I find myself eating about once a day in the time frame of around 6-8 pm. Not a ridiculously huge meal, but enough to satisfy hunger. The law of thermodynamics suggests that this drastic reduce in calories combined with my active lifestyle (basketball and/or gym everyday) should lead to me shedding a few pounds, right? Well it seems like every source on the internet says that my body will go into “starvation mode” since I have had a major reduce in calorie intake per day. These sources state that the calories I do consume will be turned into fat and will not be burned off as they normally would.

This strikes me as confusing as aren’t all carbs fat and protein that are unused in cell building, physical activity etc turned into fat cells anyways? How does my body just slow down the burning of calories when I’m in the middle of running down the basketball court? I guess I’m just asking for a very exact definition of what this starvation mode is, and how it fits in the law of thermodynamics and why I can not just eat absolutely nothing and run 10 miles to lose weight if I felt like it. Oh and also I’ve always wondered why I need to constantly consume calories if I have all of this fat (energy) stored up already. Thanks

2

Short answer is, when the body detects its intake of calories is slowing down it slows down it’s metabolism to compensate. Also, sleeping during the day and being awake at night also makes the metabolism slow down as well. You also may not realize how many calories you’re actually eating. Shift workers typically way overeat at night and gain weight because of it. It’s really easy to eat 2000 calories in a night and not even know it.

3

Well the idea is that I’m eating less calories than before. I know that for a fact. What do you mean by it slows down the metabolism? If I run now, is it burning less calories than if I ran last month? I think I need a long answer to satisfy my thirst (or hunger).

4

I think the OP wants to know: if the body can make itself “more efficient”, then why isn’t it always so? What is the evolutionary downside to always being in “starvation mode”. Also, what is meant by “lowered metabolism”? By conservation of energy, I would assume it means that the mean body temperature is reduced somewhat? Does that mean that the downside is lowered immune function?

5

I feel so 1-up’d, but yes that is pretty much exactly what I am asking. Thanks for being able to word that so much better than I did. :stuck_out_tongue:

6

How much are you drinking? Being on a vacation from college and running around with your friends, I presume that you’re drinking a lot of beer. That has calories in it. Are you snacking while drinking?

7

I’m not drinking anything except water and crystal light. I’m just getting out of my first semester, I’m still a kid. Trust me on this, the amount of calories are not the issue. The issue is where they are going and what’s happening to them in this mysterious ‘starvation mode’. I haven’t been snacking or drinking anything caloric. And btw, I’m not necessarily tryinggg to lose weight but if I shed a few pounds my next semester may be better than expected

8

In starvation mode the body suppresses all unnecessary functions. It is a way for the body to ride out seasonal droughts by conserving energy. Brian function slows, hours of sleep increase, unconscious movements such as fidgetting decrease. The brain becomes becomes listless and finds difficulty focusing on anything, leading to a decrease in physical activity. Muscles begin to atrophy faster than normal for the same level of use.

Most people seriously underestimate the amount of energy burned doing pointless things, especially amongst younger people. Running up or down a flight of stairs, hand gestures when talking, 5 minutes spent looking at something interesting. It all adds up, and it all declines when the body is chronically malnourished.

The downside is pretty much the same as the upside. People stop thinking and exploring and innovating, Their work output declines, their progress halts. It’s really not a good thing except in emergencies.

I’ve never heard of any decline in body temperature, though with increased sleep I expect that the daily mean would decline.

9

FWIW, I did the same thing during Spring Break '86. Someone stole my purse so I had only the few bucks in my pocket for food for the week. One day, all I had to eat was a Reese Cup. At night, we went to clubs which offered free drinks for women, which I took advantage of. We danced til the wee hours of the morning.

I lost 20 pounds in one week.

10

There’s no metabolic dissonance to explain, although it’s easy to see why you might think there is. The way most people explain things contributes to the confusion.

On the one hand, your body’s metabolism really can slow itself down to conserve energy. That means you may lose less or the same amount of weight while eating a severely restricted diet as you would eating a moderately restricted diet. But as a bottom line - if you literally starve yourself for an extended period of time your body will rapidly lose weight. There’s no magic going on.

On the other hand, what people talk about is the fact that your body’s metabolism won’t adjust back quickly. So even if you do lose weight now, when you go back to school and normal eating habits your body’s metabolism will remain slowed and you’ll quickly gain weight. That contributes to yoyo dieting.

There seems to be a perception that severely restricted diets are always bad and basically a mistake people who don`t know anything about nutrition make. And that’s absolutely true for someone who is just overweight or who is dieting at home on their own. But a very low calorie diet (800/day or less) under a doctor’s care is a common way to treat obesity for patients with the ability to stick to a severe diet like that over a short time. The doctor will provide nutritionally complete liquid protein supplements and carefully monitor the patient during the course of the treatment. You should expect to lose 3-5 pounds per week. Personally I worked with my bariatrician doing exactly this and lost about 40 pounds in 6 weeks.

11

If you want a more detailed and critical analysis of what’s going on with your metabolism when you eat or don’t eat various foods, you might want to pick up a copy of Gary Taubes Good Calories, Bad Calories. The whole thing is much more complicated than “calories in, calories out”. If you don’t want to wade through the whole book, start at the last section on weight loss.

12

There’s no such thing as bad calories or good calories in the context of weight loss.

A calorie is a calorie, period.

If you eat 3500 calories in excess of what you burn, you accumulate one pound of body fat. If you burn 3500 calories in excess of what you consume, you lose one pound of body fat.

The variability is of course the “burn.” You can take two people of the exact same height, weight, and build and with the exact same daily activity and their amount of calories burned will be different. The difference could be imperceptible or it could be relatively significant.

At the end of the day, though, if you simply measure your weight every day and track it continually you’ll be able to calculate a moving average and compare that to your caloric intake. From these numbers you’ll be able to determine how much you personally burn, and from there you can make adjustments to your intake for more or less guaranteed weight loss.

Also I should add that it is pretty much impossible to lose 20 pounds of body fat in a single week.

Take a 200 pound person, let’s estimate they are burning 15 calories per pound of weight each day, for 3000 calories burned per day. That number I grabbed out of the air, 15, as the multiplier is much higher than what you’d see in the real world. A person who exercises an hour a day at that weight would probably in reality burn something like 2400 calories daily. Unless you’re doing insane levels of physical activity (like you’re in the Tour de France) you probably won’t be burning more than 3000 a day even living a very “active” normal life (meaning you work as someone who is on their feet moving all day and spend some time at the gym each day.)

So our hypothetical 200 pound person is burning 3000 calories a day, let’s also say they eat absolutely no food for 7 days, nothing with any calories whatsoever. That means they create a caloric deficit of 21,000 over the week, that is exactly 7.7 lbs of weight loss.

Now, do I doubt that someone who did this might look at the scale after that week and see a decrease far more than 7 pounds? Sure, but scale weight is only useful as an indicator of actual weight if you weigh yourself under the same conditions every single day and create a metric for watching the trend. This is because your body moves a lot of mass through it in a single day relative to the mass of any fat you are actually losing. For example our person in the starvation diet above was losing something like 13.6 oz of fat per day, but moving many many more pounds of water and other materials through their body over that time. How much of that water your body holds on to is also not going to be set in stone and will vary.

13

I’ll also add a disclaimer about the 20 lbs of fat loss in a week, your burn is obviously a function of your weight. If you are extremely obese of course you might be burning more than 3000 calories a day just because of all the energy you body needs to move you around and do your daily activities. I’d say most people who weigh 300+ lbs probably burn 3000 calories a day even in a sedentary lifestyle. However, it should also be noted that extremely obese people do burn fewer calories per pound than muscular or even just normally “fit” people.

So when I say it is impossible to lose 20 lbs of fat in a week I’m talking about people within “normal” and even up to “very overweight” ranges. Someone who is extremely obese could probably legitimately lose 20 lbs of fat in a single week.

14

It’s worth noting that “starvation mode” doesn’t mean you won’t lose weight, it just means that you hit diminishing returns, and understanding this can hep determine the best long term program.

Let’s say Suzie’s maintains on 2000 calories a day. She wants to lose weight, and so cuts down to 1500 a day. She loses at a nice, steady pound a week. At that calorie level, she’s hungry, but not terribly so, and she can fit in the occasional indulgence so that she doesn’t feel terribly deprived. However, she’s heard that two pounds a week is what you are “supposed” to lose, so she cuts out another 500, down to 1000 calories a day. That second 500 makes a much bigger difference in her quality of life: now she is hungry all the time, has headaches, less energy, is absent minded, and has to plan her eating like the invasion of Normandy to make sure she gets her basic nutrients in. She’s eating from a very limited palate of foods, and finds it virtually impossible to eat socially or indulge in anything that isn’t both bulky and nutritious. The real kicker, however, is that that second 500 calorie cut probably won’t lead to a second pound a week loss: it’ll lead to a half pound a week loss, or a quarter pound a week loss. All those symptoms she’s experiencing: the lethargy, the headaches, the constipation, the absent-mindedness, all those are the result of her body slamming the breaks on her metabolism in reaction to what is now a severe shortage of energy.

Basically, she’s suffering twice as much to gain half as much. This is a phenomenon not unique to weight loss–it’s why we have the term “diminishing returns”. It seems to occur in virtually all systems.

In terms of weight loss, the diminishing returns mean that a more strict plan is less likely to result in long term success. All that extra suffering for a small gain in rate often discourages people and they give up altogether. Also, dieting right on the edge of your endurance means that when additional stressors enter your life (midterms, your dog dies, your mom gets fired, your SO gets sick), you don’t have the resources to do everything and you tend to go back to old eating habits.

15

That’s not entirely true. While it’s definitely possible to get fat on too many calories from healthy foods, a diet that’s not composed of healthy foods is very difficult to follow and may undermine your overall health, which in turn will affect your ability (and willingness) to burn calories. The body also doesn’t handle all foods identically; things like blood sugar spikes, protein availability after workouts, and satiety from fiber are all worth due consideration. Even more than just feeling more hungry and less energy, what you eat can affect your base metabolism pretty quickly, too.

Sure, you can lose weight on 1,000 calories of cane sugar a day, hypothetically. That doesn’t mean it’s not a bad diet.

16

I didn’t say that eating a bowl of sugar a day wouldn’t be a bad diet. I just said for the purposes of weight loss, all calories are the same.

All the other factors of “bad for you” foods aren’t strictly associated with the biology of energy consumption and storage as fat and efforts to reduce the amount of stored fat. The food you eat has a ton of impacts on your overall health and behavior far and above the strict calories. However for the purposes of fat reduction all that matters is the raw number of calories.

I don’t deny that a balanced, healthy diet is going to be more sustainable and make you feel better in the long run. “Feeling full” is a key part of being able to stay on a diet. For that reason foods like potato chips and soda are anathema to a good diet because they have high calories but don’t leave you feeling that full.

On the other hand, you can eat some cottage cheese and may only consume about 100 calories but it makes you feel full. So I definitely agree some foods are more suited for a successful diet than others. I don’t like the connotations of terms like “good calories” and “bad calories” when talking about weight loss though. You can in fact lose weight eating 1500 calories a day entirely from bowls of sugar. I would absolutely recommend against that as I’m sure you would die from it eventually (even if not from the negative effects of the sugar then from the various nutrients you’d ostensibly not be consuming.)

I actually think bad/good calorie concepts can hurt people who are dieting because it makes people think they are locked into a rigid system where they can never touch the “bad” foods. My philosophy (and what worked for me when losing weight) is that if you really want something, eat it. But you have to learn to control it. If you’re on a diet and you really want a cheeseburger, plan to eat a cheeseburger the next day. Don’t change your diet mid-day, I think a key part of successful dieting is actually planning out everything you eat in advance, so I think it is important to maintain discipline once the day has began. But if you’re really crazing a cheeseburger, just schedule yourself one the next day. Don’t let it change the big picture though, it might mean that you don’t get to eat lunch because you’re consuming so many extra calories at dinner, but you need to have the discipline to do that.

17

One thing about a starvation diet for me is that I get very cold. Clearly my body temperature, cool at best (my normal waking temperature is around 97.2 F) goes even lower. I feel, though, that an active lifestyle helps keep my metabolism up, though.

Can you lose 20 lb in a week? Think of it this way. A moderately active person might burn 2500 calories a day. So if you fasted for a week (don’t do it!) and kept up your metabolism, you would be short 17,500 calories. At 3500 calories for a pound of fat, that means you would lose 5 pounds. I can gain 3 pounds just by having a meal in a Chinese restaurant (very high in soy sauce) and lose 3 pounds two days later as my water and salt balance return to normal. This has nothing to do with either gaining or losing fat, only water.

18

That last thing you said is so important I wanted to hit on it again. Scales don’t measure fat, they measure weight. Obviously you don’t need to weigh yourself at all to know you’re getting thinner, but if you want to use that weight on the scale as a reliable metric it needs to be daily weigh ins continuously throughout your diet.

Weight watchers works because if you follow the guidelines exactly you’re just calorie counting and creating a deficit (and it’ll be true for most people on the planet that if you follow WW guidelines you’re creating a deficit), but their weekly weigh in system leaves a lot to be desired to my mind. The only reason I can give for it is 99% of people have no idea what a scale actually measures and thus most dieters will freak out over the daily variations, weighing weekly will usually isolate you from that to a degree–but it also can result in “diet depression” if you have a bad weekly weigh in because you happened to weigh yourself on a day where you had a few extra pounds of water floating around in your system. Daily weigh ins with a proper moving average being taken will smooth out the curve and show you a more accurate representation than what is actually happening. It essentially frees you from “scale anxiety” as long as you’re actually following a diet. (Because of its accuracy it also means if your average is trending up you know you actually are gaining weight, and need to adjust.)

19

Contrary to popular opinion, you’re not in “starvation mode.” Starvation is about blood sugar, not calories. This is how the Atkins diet works.

If you are maintaining stable blood sugar levels, you have all the the calories you’ll need. In fact, your body’s probably banking excess sugar in the form of glucagon reserves in your liver, which can store about 8 hours’ worth of sugar. In order to truly go into starvation mode, blood sugar levels must remain below a certain level (don’t know it off the top of my head) for several days.

So, one large meal/day, coupled with lots of time sleeping suggests that you are simply maintaining the status quo, and are nowhere near ‘starvation mode.’

20

Here’s a long, but good on-line e-book on the subject.

The Hacker’s Diet