"starvation mode'

Found this article found it pretty interesting and answered a lot of questions. I know its long article, but it think its worth the read.

If you've been on a diet, you've surely heard about it. The dreaded starvation mode. How many people have said to you, "be careful not to dip below 1200 calories. Your body will go into starvation mode and you'll gain weight." Or, what about, "Oh, you're not eating enough, that's why you're not losing weight. Your body is in starvation mode." A frightful sounding thing indeed. It seems like a dieter just can't win. If they eat too much, they won't lose weight. If they eat too little, they won't lose weight. Can all this really be true?
The simple answer is no. Starvation mode has been embellished so much that it's almost a complete lie at this point. So what is starvation mode really? Starvation mode, more formally known as famine response, is part of your body's survival mechanism. When you aren't getting a sufficient amount of calories to run your body, your body does indeed fall into famine response, because normally, when one isn't eating, it's because there is nothing to eat. Starvation mode slows down the body's metabolism to try and save as much energy as it can. It also breaks down muscle, but I'll go into that a bit later. So, yes, famine response, or starvation mode, does slow down your metabolism and does break down muscle, but that's where the truth ends and the embellishment begins.

Firstly, starvation mode is not something that kicks in automatically. If you skip a day of eating, your body is not going to freak out and drop your metabolism to a slow crawl. Starvation mode kicks in after continuous fasting or severe calorie restriction, usually longer than a week, but at least 3 days. If you've fasted, or restricted calories severely, you know the feelings of hunger pangs and how horrible they were. That's your body saying, "Eat. I need fuel." Since your body is telling you to eat, it believes there is still food to be eaten, so no starvation mode yet. When the hunger subsides, usually after about 3 to 5 days, your body has decided to there must not be food and uses alternative energy sources. This is a good indication that starvation mode is not far away.

People also believe that starvation mode will make you gain weight. This is essentially false. Starvation mode does slow down the metabolism, but if you are eating so little that starvation mode has set in, you are not going to gain weight. The percentage by which the metabolism slows down, which can be as much as 40 percent, does not overshadow the calorie deficit. All it means is that, if you are eating 500 calories a day, and you are supposed to get 2000, you should lose 3 pounds a week with your metabolism running normally. Let's say your metabolism dropped 30 percent. You would have a basal metabolic rate of 1400 calories a day instead, and so you would lose 1.8 pounds a week instead. Considerably fewer amounts of weight, but you would still lose weight. You can not gain weight by taking in fewer calories a day. It does not make sense scientifically, especially if you understand physics.

Let's get back to the muscle loss, because that is concerning to most people. Starvation mode does cause muscle loss, partially because it is getting rid of something that uses a lot of energy and partially because it needs protein, which it takes from the muscle. However, what most people don't know is that every diet causes muscle loss, even healthy ones. A healthy lower of calories, that is a 500 calorie deficit, will cause 75 percent fat loss and 25 percent muscle loss. Starvation diets cause a 50 percent fat loss, and a 50 percent muscle loss, however, this has two main causes. The body is not getting enough protein, and people eating small amounts of food, or no food, usually do not have the energy to do strength training. Not that the Atkin's Diet pushes the body into starvation mode, but does not cause excessive muscle loss. This is because Atkin's followers get massive amounts of proteins and so the body does not need to take protein from the muscles and most do strength training, to prevent excessive muscle loss. It works. They end up with the more average 75/25 fat/muscle loss ratio. So, if a person eating 500 calories a day ate it all in protein, and had the strength to do some strength training, they would conceivably end up with a 75/25 ratio as well, or at least something close to that.

This is all very interesting, you think, but why should I believe you? Your just a random person writing on the internet. Good point. Let me give you some examples. First, basic anatomy. The body uses glucose as fuel. Well, no food equals no glucose. So what does the body do? It breaks down fat. It has to break down fat because it uses the glycerol there to fuel the body. There is no possible way for the body not to break down fat, because it would die otherwise. It also uses the ketones produced by the breakdown of fats to fuel the brain, and the brain is obviously very important. There's also the Minnesota Semi-Starvation Study, that took place in 1944. The men ended up losing 25% of their starting body weights, even though their metabolisms slowed by 40 percent, and they were of average weight to begin with. Anorectics, who impose starvation on themselves, also disprove most of the starvation mode myths. They do not gain weight or stay the same. They continue to lose weight, even though they are severely underweight. Finally, Very Low Calorie Diets are used by physicians to treat obesity in some cases, and these diets are typically under 800 calories daily.

There you have it. The reality of starvation mode. Not nearly as frightening as made out to be. Of course, I don't support starvation type diets, and these will make you gain weight. Most likely because you will be very hungry, and most people do not have the willpower to consistently eat very little and will end up binging, and yes, your body will hold on to those calories because it has already depleted some of its storage, and you will gain weight. Furthermore, starvation diets tend not to give your body enough nutrients. Did you know a potassium deficiency can cause a heart attack? Not something you want to play around with. That being said, if you drop below your calories for a day, you don't have to fear a dead metabolism and rapid weight gain.

Sources
The Biology of Human Starvation, University of Minnesota Press, 1950.

http://voices.yahoo.com/starvation-mode-dispelling-myths-2900886.html?cat=5