Starvation diet efficacy
 

I am wondering if someone could explain this to me. I keep reading that if you go below 1200 calories it's considered a starvation diet, especially if you start at a weight that is significantly high. Therefore, your body will hold onto the fat since it thinks your body is starving and also cause hair loss, vitamin deficiency , etc. So, if you get weightloss surgery or just only manage to take in 800 or less cals per day how do you still lose weight? By the previous logic wouldn't your body try to hold onto the fat rather than lose it quite rapidly. So, I guess I'm just confused. Even if you ate zero calories wouldn't your body have to use your extra stored fat daily for function resulting in quick weight loss? I can't understand how a body that is overweight can hold onto fat. Shouldn't it be fewer cals in, more cals deficient= more weight loss. I am also assuming your body would first lose only fat then a combo of fat/muscle if u weren't taking in appropriate protein.

Does a human really need protein/fats/carbs daily if their body is already working to burn what is stored? Is weightloss acheived while eating these extra things at a slower rate only to avoid suffering extreme hunger/vitamin & mood issues? Sorry if it sounds totally ignorant I'm just wondering how the body truly works.

Weight Watchers says in their science related papers that it is a myth to say that people eating below X calories will not lose weight due to starvation mode. Articles I have read point out that when people die of starvation, well, they get very thin first.

What I did read is that if you do significantly cut calories that metabolism can slow somewhat but that is not the same as starvation mode.

Basically if you eat very low calories you will in fact lose weight. But, there are problems with eating very low calories. For one thing, it is hard (and can be impossible) to get good nutrition on very low calories. You can lack energy and find it difficult to do anything. And, for many people, eating extremely low calories doesn't foster much of a lifetime eating plan. And if you are really hungry there is the issue of rebounding with a vengeance.

Right now, I am eating about 1200 cal a day but more on days that I am active. I am not super hungry though and will eat more if I am hungry or go out.

OK so the "starvation" theory goes like this.

The human body is built, 100%, for survival. One of the things that can threaten survival is starvation. So the body has mechanisms to, essentially, make you burn fewer calories when your body is getting signals that you are starving. There are a variety of mechanisms for this. The basal body temperature will drop, meaning you expend less energy to keep yourself warm. Your body will consume muscle preferentially to fat (although fat will also be lost), because muscle burns more calories at rest than fat does, and therefore eliminating muscle will make you burn fewer calories just to stay alive. Your release of thyroid hormone will drop. Basically, your entire body will start fine tuning itself to burn fewer calories, using all kinds of mechanisms, because it doesn't want to starve and thinks that it is.

So let's say that your current "normal" metabolism burns 1400 calories a day to stay alive/breathing/etc. If your body made a variety of tweaks, consumed muscle, switched hormonal balances, and etc to conserve energy, it might only require 800 calories a day to stay alive/breathing, because you'd have less muscle, your body temperature would be lower, and your body would have made a bunch of little tiny changes aimed at conserving energy (calories). In addition, this perceived stress on your body will trigger the release of cortisol, a hormone that encourages body tissues to store more fat and instead consume muscle and slows down your thyroid, which make the issue worse.

Of course, you're always going to need SOME calories to live, so true starvation will eventually kill you. But starvation will reduce the amount of calories that your body needs to survive, so that you lose weight more slowly than you'd expect, and you'll be able to eat less to maintain. Again, take that hypothetical example of a 1200 cal/day basal metabolic rate. If you starved yourself and reduced your basal metabolic rate to 800 cal/day, to lose you'd have to eat LESS than that, and to maintain, you'd be stuck at 800. If your metabolism hadn't reduced as such, you'd be able to lose at 1000 and maintain at 1200.

There is a lot of debate over where exactly the calorie level falls wherein your body starts this process and your metabolism is effected. The 1200 number is given for average women...women who are very small or petite may be able to eat below that without causing their bodies any stress. But every body that gets to a certain low level (which, again, may vary from person to person) will reach a level where their body starts to slow itself down, resulting in slower losses and a slower metabolism at maintenance.

Wanted to add - the reason a lot of people say that starvation mode "doesn't exist" is that eventually, even people who are starving will lose weight and die. And that's totally true. Even the worst starvation can't set your metabolism to 0, and if you're taking in less than whatever you burn, you'll lose weight. So yes, people still get skinny by starving themselves. But the calorie total they burn in a day to keep themselves alive is significantly lower than it would have otherwise been (thus the reason that anorexics in eating disorder treatment often gain weight quickly, which often leads to relapse...even at 1200 cals a day, someone whose metabolism has signficantly slowed due to starvation can gain a pound in a week or two).

Thank you so much! I have a much better understanding of it now. I was so confused when I was reading what had seemed like conflicting statements about losing. I am going to come back and re-read when I have more time today but everything you wrote is spot on and exactly what I was hoping to learn.

Some people use the term "conservation mode," in place of "starvation mode," because it's somewhat less misleading.

It helps to remember that you can slow metabolism, but you can't stop it. Science is understanding more and more of both the mechanisms for slowing and increasing metabolism, but for the average dieter, trial and error is what most of us are left with.

By experimenting with your diet (both in terms of carb/fat/protein proportions and calorie levels) you can learn a lot about your own metabolism and other weight loss factor (such as which foods fill you up longer).

For example, I learned that I lose more weight and am less hungry on 1800 calories of low-carb, than on 1800 calories of higher carb eating. If I eat fewer than 1500 calories, I have absolutely far less energy for even basic activities, and I sleep more, but feel less rested.

A good food journal can teach you alot about what works best for you. The thing to remember is that it takes months to see true patterns, because what you see on the scale today may have more to do what you've done last month, than what you've done yesterday, or even last week.

Here is the link to the article on the WW site about the starvation myth. It cites several science articles with links to them in the footnote. They do point out that while metabolism doesn't shut down with eating very low calories that it may slow and that there are other reason why eating very low calories often doesn't work out well.

http://www.weightwatchers.com/util/a...of+Weight+Loss