Everything you read may not be true

Let's face it the internet is a fantastic resource for research. However it also the source for many misconceptions and many of the points raised are not backed up by any scientific data to prove, or disprove a point. No more is the case than the research I have been doing trying to understand how the human body reacts to dieting. I have come across many health and well being sites which have warned about under eating quaoting that the body goes into "starvation mode" and will hold onto every last ounce of fat and that you will not loose weight if you continue to under eat you calculated daily calorific needs. This is the first "myth" that I had to get to the bottom of. It just didn't make sense to me. I considered the prisoners of war in Burma and seeing the emaciated bodies of the POW after months of very low calorie intakes and more laterly the Chilean Miners who were stuck underground for 69 days with very little food during the 2010 mining disaster. In each case the miners had lost significant body weight ( around 8Kg per miner)

With this fact I was sure there must have been some research into how the body reacts when forced into a starvation mode. It so happened that a study was carried out just after WW2 when there wre thousands of people affected by "starvation" and more importantly those who had suffered subsequently died after being fed normal food levels as their bodies could no longer digest the food properly.

If we consider the medical facts surrounding starvation. The brain is the most vital organ in our body and is responsible for consuming about 20% of our daily energy requirements. The brain must be kept in as good functional  and alert condition to help us find food to survive This energy requirement is fulfilled by using glucose in the blood.  The brain requires some 120g of glucose per day.

Glucose can be obtained directly from dietary sugars and carbohydrates. In the absence of dietary sugars and carbohydrates, it is obtained from the breakdown of glycogen. Glycogen is a readily-accessible storage form of glucose, stored in small quantities in the liver and muscles. The body's glycogen reserve can provide glucose for about 6 hours. After the glycogen reserve is used up, glucose can be obtained from the breakdown of fats. Fats from adipose ( normally found in the abdomen) tissue are broken down into glycerol and free fatty acids. Glycerol can then be used by the liver as a substrate for gluconeogenesis, to produce glucose for use throughout the body.

After several days of under eating, r starvation, all cells in the body begin to break down protein. This releases amino acids into the bloodstream, which can be converted into glucose by the liver. Since much of our muscle mass is protein, this phenomenon is responsible for the wasting away of muscle mass seen in starvation.

However, the body is able to selectively decide which cells will break down protein and which will not. About 2–3 g of protein has to be broken down to synthesise 1g of glucose; about 20–30 g of protein is broken down each day to make glucose to keep the brain alive. However, this number may decrease the longer the fasting period is continued in order to conserve protein.

Starvation ensues when the fat reserves are completely exhausted and protein is the only fuel source available to the body. Thus, after periods of starvation, the loss of body protein affects the function of important organs, and death results, even if there are still fat reserves left unused. (In a leaner person, the fat reserves are depleted earlier, the protein depletion occurs sooner, and therefore death occurs sooner.) (souce WiKipedia - starvation response)

So, in my interpretation of this starvation myth theory I have to be unconvinced. Providing the body has enough daily intake of essential fats, carbohydrates and protein then even an overly restricted calorie intake is going to produce a proportional weight loss. The only "danger" is the way the body responds to such reduced levels like lack producing of concentration, endurance, sexual performance and mental health well being.