[enraged_camel]

The Vermont Prison Overfeeding Study actually perfectly explains what you experience on low calorie diets.

http://idealbodyweights.blogspot.com/2009/08/vermont-prison-...

"The rapid weight loss these prisoners experienced is the mirror image of what happens when overweight people try to lose weight. If your set point is too high and you try to lose weight quickly, your body will fight to defend that weight and slow down your metabolism. But if your set point is within a normal range, your metabolism will speed up when you gain weight quickly."

In other words, if you have been fat for a while, then drastically reducing calories will cause your body to fight the changes, which will make you feel sick and cold for a while. That said, adjustment is inevitable.

Low carb and zero carb diets are great for losing weight reliably though, because without carbs the pancreas does not secrete insulin, which means your body cannot store the excess calories in adipose tissue. So it either has to burn it or excrete it.

[jacques_chester]

You are wrong. The body can and does assimilate dietary fat into adipose tissue.

Low-carb diets work by reducing total dietary calories; a secondary contributing cause is satiety from an increase in protein.

[enraged_camel]

How does it do that without insulin?

[magnusson]

Acylation Stimulating Protein

[enraged_camel]

ASP stores fat in adipose tissue, but it's nowhere as effective as insulin. ASP secretion is controlled by chylomicrons, which are very short lived, and that makes it so that only a very limited amount of dietary fat can be stored as body fat.

[magnusson]

>a very limited amount of dietary fat can be stored as body fat

In the complete absence of insulin, maybe, which is almost never the case in normal dietary conditions, since both protein and carbohydrate stimulate insulin secretion. But dietary fat is nonetheless the primary source of body fat; direct conversion of dietary carbohydrate to body fat is not a quantitatively significant process in humans except for in extreme conditions. See De novo lipogenesis in humans: metabolic and regulatory aspects. http://www.ncbi.nlm.nih.gov/pubmed/10365981

"Only when CHO energy intake exceeds TEE does DNL in liver or adipose tissue contribute significantly to the whole-body energy economy."