The reason why starving yourself WILL NOT work.

Before MFP, I was guilty of using the "starvation diet" over and over in hopes that I would lose weight fast. It never stayed off and I never felt smaller. Now I see that I really was creating more set backs to actually changing my lifestyle and keeping the weight off. Thanks so much for this very informative post. It's even more incentive to finally do this the right way and change my life for the better! :-)

great post...but how do you know what the right amount of calories should be??? I have a lot of trouble with this....

When you enter your details into MFP it will generate a rough estimate of what you need to lose, maintain, or gain weight. Once you stay within 100 to 200 cals of this you're safe enough, just don't eat under 1200!

Ok, thanks...MFP has me at 1200/day.....I am only 5'1" and weigh 149 right now. I am trying to get down to around 125. I wasnt sure if 1200/day was right for me, I seemed to have stopped losing the weight. I do eat right up to my 1200, sometimes over if I worked out that day. I never feel starving or anything, just wanted to know if I was doing the right thing...

Firstly, it's not true that fat burning ceases during starvation, it's just that the body will be burning significant amounts of lean mass along with the fat, and trying to preserve the fat stores as long as possible. By the time you starve yourself down to 1% body fat, you'll have no skeletal muscle left, and you'll look like a walking skeleton. But fat loss doesn't cease, it just slows. So on a starvation diet, you lose fat, but you lose a lot of muscle as well, and there are other negative effects such as loss of bone density and all sorts. (just wanted to clear that up before answering the following question)

0% body fat = dead, the fat isn't just a store of energy, it has an important role in hormone regulation and other systems in the body, and it's essential for proper functioning of the nervous system, i.e. the role of essential body fat which is around 3-4% in men and 13% in women.

Why does the body go to the muscles instead of burning off the fat first?

the body's objective is to survive a food shortage. You have to view this in the context of natural selection. Our evolutionary ancestors were subjected to frequent food shortages, and we are descended from the survivors of food shortages.

Had any of those ancestors had bodies that burned off all the fat before burning off any muscle, they would have been among the first to die in these food shortages, so we're not descended from anyone whose body worked like that, natural selection has prevented that characteristic remaining in the gene pool. Why? Because muscle cells burn a lot of energy to stay alive, while fat cells don't burn much energy. Both are a source of energy for the body. But by jettisoning the muscle cells in preference to fat cells, the body is conserving energy twice. Once, because it's using the energy from burning the muscle cells, and twice because it no longer has to spend energy keeping those muscle cells alive. Fat on the other hand, requires less energy to stay alive, so it's better to conserve the fat as long as possible, and sacrifice the muscle cells. Those of our ancestors whose bodies worked like this survived the food shortages and those genes stayed in the population, and are found in us too.

Additionally, unused muscle is jettisoned long before muscle that's used regularly. Simply because our ancestors were hunter-gatherers, to get food they needed to use muscle. However, muscles that were not being regularly used were a liability. They give the body no benefit (i.e. they're not necessary for successful hunting/gathering) and they cost a lot of energy to maintain. therefore they get jettisoned first. This jettisoning of unused muscle can happen even when eating at a maintenance or a very small deficit, and you can see this happen if someone who used to be very active becomes sedentary, even if they carry on eating enough to maintain their body weight. The human body prefers energy efficiency, because of all those millions of years of natural selection in favour of people who could survive food shortages. So on any kind of diet, even a sensible one, heavy lifting goes a long way to preserve lean body mass, because in our ancestors, muscle that was used regularly = essential muscle for hunting = lose that and you become an evolutionary failure because you can't obtain food. Obtaining food in a food shortage is a significant evolutionary advantage.

I hope that explanation makes sense. In any case, the take home message is to lose *fat* and minimise lean body mass losses, you need a sensible deficit, and exercise that puts sufficient stimulus on the muscles to prevent them being jettisoned for energy efficiency. From an evolutionary perspective, you're imitating being a successful hunter in a mild food shortage. Your body will keep the muscle you use so you can keep being successful at hunting, and burn the fat to make up the energy shortfall from the mild food shortage, in the hope that you'll hunt enough to eat at maintenance further down the line. This is what has "won" at natural selection in the past. But if you start imitating someone not hunting during a severe food shortage, you're going to have the effects that give you the best chance of surviving in those circumstances, i.e. totally wasted muscles and your body trying to make your fat stores last as long as possible. (and heavy exercise in a severe food shortage isn't a good idea because the human body can't make something from nothing, there is a point at which you're going to be an evolutionary failure no matter what - no organism has evolved the ability to be invincible or break the laws of physics)

Losing real weight from starving is physically impossible. Your body absolutely can not lose that much weight in a week.

I wonder if the person who posted they were not eating any more just drinking fluids is still alive today? Since this is from 2011 it would be interesting to know if they smartened up.

I think this is all speculation.

I look to the bear.