Taking in less Calories than BMR greatly increases the chance of developing the following diseases- severe loss of muscle tissue (as much as 40% of total wt lost), fragile and premature ageing of skin, bone mineral loss and subsequent osteoporosis, gout, gall stones, cholecystitis, vasovagal fainting (dangerous when driving), hypoglycaemia, cardiac arrhythmias, vitamin and mineral deficiencies, and nervous system dysfunction. When sustained, anorexia nervosa will develop.
A very important point indeed...
From
http://ezinearticles.com/?The-Danger-of-Low-Calorie-Diets:-How-To-Avoid-The-Yo-Yo-Diet-Trap&id=74029
"While low calorie diets can result in weight loss in the first few weeks and months of starting the diet,
the majority of the weight lost is not fat. This is because
low calorie diets do not provide sufficient energy to fuel the body’s basic functions such as breathing, circulation, and digestion etc. In order to provide the fuel to keep itself alive, the body breaks down muscle tissue, which is easily convertible into glucose, and is easier to access and break down into energy than fat.
In effect,
low calorie diets reduce the amount of lean muscle tissue in the body, which has a knock-on effect of reducing the basal metabolic rate. Lean muscle tissue is metabolically active, meaning that the more lean muscle tissue an individual has, the more calories are burned. The reduction in lean muscle tissue also reduces the body’s ability to burn fat.
When you finally lose the weight and start eating normally, your body can no longer burn calories at the rate it did before your diet because you now have less lean muscle tissue! You become locked in a vicious cycle of dieting and weight gain - simply because your body breaks down muscle for glucose before it breaks down fat. Although you might only end up gaining back the original weight you lost, you are will end up fatter because you have lost lean muscle tissue and gained back fat.
The result of the loss of lean muscle tissue and the weight gain arising from it is termed the Yo-Yo effect. Many dieters, when finding that they have regained the weight they have lost, embark on another diet, which plunges them further into lean muscle tissue loss.
So, what is the solution to permanent weight loss? To lose weight effectively, you need to consume enough energy to burn fat, and eat the right foods to maintain your level of lean muscle tissue. A sensible balance of a healthy diet and moderate exercise is more effective in achieving a permanent weight loss than low-calorie diets."
Low calorie diets mean you will not be getting the minerals your body requires. Deficiencies in copper, potassium and magnesium can lead to an electrically unstable heart (From
http://diet.lovetoknow.com/wiki/Dangers_of_a_Very_Low_Calorie_Diet)
From
http://dietsnutrition.allinfoabout.com/features/verylowcalorie.html
So what happens to your body on fewer than 1000 calories a day?
* Your metabolism slows down to conserve energy.
* Your body uses blood sugar, made from carbohydrates, for fuel just as a car uses gas (petrol). Without blood sugar, the brain and central nervous system, as well as other bodily systems, will cease to work efficiently.
* To try to counteract the lack of blood sugar from carbohydrates in the diet, your body will break down fat, which is what you want, but it will also breakdown muscle and other lean body tissue.
* Losing lean body tissue can be very dangerous.
Even organs can be broken down to use as fuel.
* Losing lean body tissue can also be counter-productive. Muscle tissue increases the resting metabolic rate.
With reduced amounts of muscle, your metabolism will slow. When you come off the diet, increased fat cells will form because your metabolism is slow and so your body needs less blood sugar for fuel. It is also a survival mechanism in case of another 'famine'.
* With very low calorie diets, an imbalance in minerals and electrolytes can occur, which can be dangerous. These govern the balance of fluids in the body allowing nerves and muscles to function.
*
Osteoporosis can be another danger, especially for women. Often dairy products like eggs, milk and cheese are cut out of a very low calorie diet so cutting out a major source of calcium leading to loss of bone mass.
*
Anaemia (a lack of iron in the blood) can also be another risk. If taken to extremes, women can find that menstuation (periods) becomes irregular or stops altogether.
* A lack of serotonin in the brain can be another problem which leads to
clinical depression.
* You might find that the lack of essential nutrients on a very low calorie diet leads to a deterioration in the condition of your hair and nails.
* One of the great dangers of this kind of dieting is that you can become acclimatised to it. As your body reduces some of its functions, including those of the brain and nerves, and as depression takes hold due to a lack of serotonin, you can slip into anorexia nervosa - a truly life threatening condition.
* As mentioned above, when you finally come off this diet, you will almost certainly regain all the weight you have lost plus more leading to yoyo dieting, now believed to be dangerous.
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Well well well... Many of these points were raised by others and myself on the "other" thread - especially the effects of muscle and metabolism.